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Cancer Epidemiology Biomarkers & Prevention

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Cancer Epidemiology Biomarkers & Prevention

Background: Epigenome-wide association studies are emerging in the field of cancer epidemiology with the rapid development of large-scale methylation array platforms. Until recently, these methods were only valid for DNA from flash frozen (FF) tissues. Novel techniques for repairing DNA from formalin-fixed paraffin-embedded (FFPE) tissues have emerged; however, a direct comparison of FFPE DNA repair methods before analysis on genome-wide methylation array to matched FF tissues has not been conducted.

Methods: We conducted a systematic performance comparison of two DNA repair methods (REPLI-g Ligase vs. Infinium HD Restore Kit) on FFPE-DNA compared with matched FF tissues on the Infinium 450K array. A threshold of discordant methylation between FF-FFPE pairs was set at β > 0.3. The correlations of β-values from FF–FFPE pairs were compared across methods and experimental conditions.

Results: The Illumina Restore kit outperformed the REPLI-g ligation method with respect to reproducibility of replicates (R2 > 0.970), highly correlated β-values between FF-FFPE (R2 > 0.888), and fewest discordant loci between FF-FFPE (≤0.61%). The performance of the Restore kit was validated in an independent set of 121 FFPE tissues.

Conclusions: The Restore kit outperformed RELPI-g ligation in restoring FFPE-derived DNA before analysis on the Infinium 450K methylation array. Our findings provide critical guidance that may significantly enhance the breadth of diseases that can be studied by methylomic profiling.

Impact: Epigenomic studies using FFPE tissues should now be considered among cancers that have not been fully characterized from an epigenomic standpoint. These findings promote novel epigenome-wide studies focused on cancer etiology, identification of novel biomarkers, and developing targeted therapies.

See all the articles in this CEBP Focus section, "Biomarkers, Biospecimens, and New Technologies in Molecular Epidemiology."

Cancer Epidemiol Biomarkers Prev; 23(12); 2622–31. ©2014 AACR.

miRNAs are crucial in cellular processes and have been shown to be abnormally expressed in cancer tissue and the circulation. Circulating miRNAs may serve as a novel class of minimally invasive biomarkers for prognosis. Within a first methodologic study, we evaluated the miRNA profile kinetics in the plasma of patients with colorectal cancer after surgical tumor removal to identify potential suitability as prognostic biomarkers. This pilot study is based on the ColoCare Study, a cohort study of newly diagnosed patients with stage I–IV colorectal cancer. Colorectal cancer pre- and postsurgical blood (2–7 days after surgery) and 6 months follow-up blood from 35 patients were examined and candidate miRNAs were investigated in the plasma. miRNA levels were measured by two-step qRT-PCR. Statistical analysis was performed using log-transformed normalized CT values using SAS 9.3. Comparing pre- and postsurgical miRNA levels revealed a statistically significant decrease of nine circulating miRNAs after surgery (miR92a, miR18a, miR320a, miR106a, miR16-2, miR20a, miR223, miR17, and miR143). Analyses of plasma levels over all three time points demonstrated a statistically significant decrease from presurgery to postsurgery and re-increase from postsurgery to the six months follow-up time point of four circulating miRNAs (miR92a, miR320a, miR106a, and miR18a). We were able to show for the first time that in plasma miRNA profiles change within days after colorectal cancer surgery. Our results underscore the role of the investigated miRNAs in colorectal cancer and their potential utility as prognostic biomarkers.

See all the articles in this CEBP Focus section, "Biomarkers, Biospecimens, and New Technologies in Molecular Epidemiology."

Cancer Epidemiol Biomarkers Prev; 23(12); 2632–7. ©2014 AACR.

Droplet digital PCR (ddPCR) has been successfully used with TaqMan assays to assess gene expression through the quantification of mRNA and miRNA. Recently, a new ddPCR system that can also run DNA-binding dye-based assays has been developed but it has not yet been tested for miRNA. We tested and compared the feasibility of quantifying miRNA with the new QX200 Droplet Digital PCR system when used with EvaGreen dye– and TaqMan probe–based assays. RNA from plasma and serum of 28 patients with cancer and healthy persons was reverse-transcribed and quantified for two circulating miRNAs and one added exogenous miRNA, with both EvaGreen dye–based miRCURY LNA miRNA assays and TaqMan assays. Amplification and detection of target miRNAs were performed on the QX200 ddPCR system. Conditions required to run miRCURY LNA miRNA assays were optimized. The EvaGreen-based assay was precise, reproducible over a range of concentrations of four orders of magnitude, and sensitive, detecting a target miRNA at levels down to 1 copy/μL. When this assay was compared with TaqMan assays, high concordance was obtained for two endogenous miRNAs in serum and plasma (Pearson r > 0.90). EvaGreen dye–based and TaqMan probe–based assays can be equally used with the ddPCR system to quantify circulating miRNAs in human plasma and serum. This study establishes the basis for using EvaGreen dye–based assays on a ddPCR system for quantifying circulating miRNA biomarkers and potentially other low-abundance RNA biomarkers in human biofluids.

See all the articles in this CEBP Focus section, "Biomarkers, Biospecimens, and New Technologies in Molecular Epidemiology."

Cancer Epidemiol Biomarkers Prev; 23(12); 2638–42. ©2014 AACR.

Research in the last decade suggests the clinical potential of circulating microRNAs in whole blood as biomarkers for cancer detection. However, before applying the identified circulating microRNAs clinically, biospecimen-focused research has to be performed to identify possible preanalytic variables that may significantly affect the levels of circulating microRNAs. In this study, using a unique resource of the Data Bank and BioRepository (DBBR) at Roswell Park Cancer Institute, we conducted a two-step analysis to identify internal control circulating microRNAs in whole blood and then to study how selected major preanalytic variables (namely, processing delay, storage condition, storage time, and freeze/thaw cycles) might affect the detection of circulating microRNAs. In the discovery phase of the first step, we identified three microRNAs, including miR346, miR134, and miR934, whose levels exhibited the smallest variation between the case–control groups, as well as within each group interindividually. In the further validation analysis, the consistency was validated for miR346 and miR134 but not for miR934. At the second step, using miR346 and miR134 as internal controls, we observed that as the numbers of freeze/thaw cycles increased, levels of both miR346 and miR134 were significantly decreased (Ptrend < 0.0001); varying other processing and storage conditions did not affect miRNA levels. In the paralleled analysis in plasma samples, levels of miR16 were significantly decreased by increasing processing delay and increasing numbers of freeze/thaw cycles but not affected by storage condition and duration. The results from this study highlight the necessity of biospecimen-focused research on circulating microRNAs before clinical utilization.

See all the articles in this CEBP Focus section, "Biomarkers, Biospecimens, and New Technologies in Molecular Epidemiology."

Cancer Epidemiol Biomarkers Prev; 23(12); 2643–8. ©2014 AACR.

Background: Interindividual differences in estrogen metabolism may partially account for differences in risks of estrogen-responsive cancers. We conducted a proof-of-performance study to assess the reproducibility of a LC/MS-MS method for measurement of 15 serum estrogens and metabolites (all 15 termed EM) in total (conjugated+unconjugated) and unconjugated forms and describe interindividual variation.

Methods: Interindividual variation in serum EM profiles was evaluated for 20 premenopausal women, 15 postmenopausal women, and 10 men. Replicate aliquots from 10 premenopausal women, 5 postmenopausal women, and 5 men were assayed eight times over 4 weeks. Components of variance were used to calculate coefficients of variation (CV) and intraclass correlation coefficients (ICC).

Results: In postmenopausal women and men, median EM concentrations were similar and substantially lower than that in premenopausal women. Within each sex/menopausal group, the sum of all EM varied 5- to 7-fold across extreme deciles. Some EM had greater variation; total estrone varied approximately 12-fold in premenopausal and postmenopausal women. Unconjugated estradiol varied 17-fold in postmenopausal women but only 5-fold in premenopausal women and men. CVs reflecting variation across replicate measures for individuals were <5% for most EM, but higher in some individuals with a low EM concentration. Overall laboratory CVs for all but one EM were <2% and ICCs were >99% for all EM in each group.

Conclusions: The serum EM assay has excellent laboratory reproducibility. In premenopausal women, postmenopausal women, and men, interindividual variation in EM measures is substantially greater than laboratory variation.

Impact: The serum EM assay is suitable for epidemiologic application.

See all the articles in this CEBP Focus section, "Biomarkers, Biospecimens, and New Technologies in Molecular Epidemiology."

Cancer Epidemiol Biomarkers Prev; 23(12); 2649–57. ©2014 AACR.

Background: Blood miRNAs are a new promising area of disease research, but variability in miRNA measurements may limit detection of true-positive findings. Here, we measured sources of miRNA variability and determine whether repeated measures can improve power to detect fold-change differences between comparison groups.

Methods: Blood from healthy volunteers (N = 12) was collected at three time points. The miRNAs were extracted by a method predetermined to give the highest miRNA yield. Nine different miRNAs were quantified using different qPCR assays and analyzed using mixed models to identify sources of variability. A larger number of miRNAs from a publicly available blood miRNA microarray dataset with repeated measures were used for a bootstrapping procedure to investigate effects of repeated measures on power to detect fold changes in miRNA expression for a theoretical case–control study.

Results: Technical variability in qPCR replicates was identified as a significant source of variability (P < 0.05) for all nine miRNAs tested. Variability was larger in the TaqMan qPCR assays (SD = 0.15–0.61) versus the qScript qPCR assays (SD = 0.08–0.14). Inter- and intraindividual and extraction variability also contributed significantly for two miRNAs. The bootstrapping procedure demonstrated that repeated measures (20%–50% of N) increased detection of a 2-fold change for approximately 10% to 45% more miRNAs.

Conclusion: Statistical power to detect small fold changes in blood miRNAs can be improved by accounting for sources of variability using repeated measures and choosing appropriate methods to minimize variability in miRNA quantification.

Impact: This study demonstrates the importance of including repeated measures in experimental designs for blood miRNA research.

See all the articles in this CEBP Focus section, "Biomarkers, Biospecimens, and New Technologies in Molecular Epidemiology."

Cancer Epidemiol Biomarkers Prev; 23(12); 2658–66. ©2014 AACR.

Background: Telomeres are tandem repeats of sequences present at the end of the chromosomes that maintain chromosomal integrity. After repeated cell division, telomeres shorten to a critical level, triggering replicative senescence or apoptosis, which is a key determinant of cellular aging. Short telomeres also contribute to genome instability and are a hallmark of many cancers. There are several methods for estimating telomere length (TL) from extracted DNA samples. Southern blot is accurate but requires a large quantity of DNA and is expensive. qPCR is cost-effective and requires a small quantity of DNA and is therefore widely used for large-scale epidemiologic studies; however, it typically requires triplicates. We describe a novel multiplexed probe-based non-PCR method for TL measurement.

Methods: A small amount of DNA (~50 ng) is hybridized to telomere repeat sequence–specific probes (T) and a reference single gene probes (R). T and R signals are detected from a single reaction well containing the same input DNA. Branching DNA technology is used to amplify the signal, which is detected by Luminex technology.

Results: The intra- and interassay CV (~3% and ~5%, respectively) shows the precision of the new assay and the measurements from single well correlated well with traditional single-plex qPCR run in triplicate (r = 0.7 to 0.8). The assay was also validated in an independent set of samples using Southern blot (r = 0.74).

Conclusion: We describe a novel assay for TL assessment using the Luminex platform.

Impact: This may offer an alternative cost-efficient way to study TL in extracted DNA samples.

See all the articles in this CEBP Focus section, "Biomarkers, Biospecimens, and New Technologies in Molecular Epidemiology."

Cancer Epidemiol Biomarkers Prev; 23(12); 2667–72. ©2014 AACR.

Salivary biomarkers have important potential to facilitate breakthroughs in epidemiologic studies, management of emergency situations, and detection and surveillance of diseases by medical staff. During the last decade, an increasing number of studies on salivary biomarkers have been published as a consequence of the impressive development of new high-throughput technologies. Here, we present a review of salivary biomarkers potentially useful in ionizing radiation (IR) research, particularly in molecular epidemiologic studies. Although several salivary biomarkers of cancer and other IR-associated diseases have been identified, few salivary biomarkers of exposure and no biomarker of susceptibility or effects specific to IR have been reported so far. Further studies are therefore needed to fully assess the potential of saliva as a source of biomarkers in the radiation research field. Although the use of saliva samples is not without drawbacks, it could represent an ideal noninvasive alternative to blood, particularly in children and in the context of large molecular epidemiology studies on the effects of low doses of IR, where, given the expected limited magnitude of effects, an extensive number of samples is required to reach statistical significance.

See all the articles in this CEBP Focus section, "Biomarkers, Biospecimens, and New Technologies in Molecular Epidemiology."

Cancer Epidemiol Biomarkers Prev; 23(12); 2673–80. ©2014 AACR.

The National Cancer Institute's (NCI) Surveillance, Epidemiology, and End Results (SEER) registries have been a source of biospecimens for cancer research for decades. Recently, registry-based biospecimen studies have become more practical, with the expansion of electronic networks for pathology and medical record reporting. Formalin-fixed paraffin-embedded specimens are now used for next-generation sequencing and other molecular techniques. These developments create new opportunities for SEER biospecimen research. We evaluated 31 research articles published during 2005 to 2013 based on authors' confirmation that these studies involved linkage of SEER data to biospecimens. Rather than providing an exhaustive review of all possible articles, our intent was to indicate the breadth of research made possible by such a resource. We also summarize responses to a 2012 questionnaire that was broadly distributed to the NCI intra- and extramural biospecimen research community. This included responses from 30 investigators who had used SEER biospecimens in their research. The survey was not intended to be a systematic sample, but instead to provide anecdotal insight on strengths, limitations, and the future of SEER biospecimen research. Identified strengths of this research resource include biospecimen availability, cost, and annotation of data, including demographic information, stage, and survival. Shortcomings include limited annotation of clinical attributes such as detailed chemotherapy history and recurrence, and timeliness of turnaround following biospecimen requests. A review of selected SEER biospecimen articles, investigator feedback, and technological advances reinforced our view that SEER biospecimen resources should be developed. This would advance cancer biology, etiology, and personalized therapy research.

See all the articles in this CEBP Focus section, "Biomarkers, Biospecimens, and New Technologies in Molecular Epidemiology."

Cancer Epidemiol Biomarkers Prev; 23(12); 2681–7. ©2014 AACR.

Increasingly, targeted therapies are being developed to treat malignancies. To define targets, determine mechanisms of response and resistance, and develop biomarkers for the successful investigation of novel therapeutics, high-quality tumor biospecimens are critical. We have developed standard operating procedures (SOPs) to acquire and process serial blood and tumor biopsies from patients with diffuse large B-cell lymphoma enrolled in multicenter clinical trials. These SOPs allow for collection and processing of materials suitable for multiple downstream applications, including immunohistochemistry, cDNA microarrays, exome sequencing, and metabolomics. By standardizing these methods, we control preanalytic variables that ensure high reproducibility of results and facilitate the integration of datasets from such trials. This will facilitate translational research, better treatment selection, and more rapid and efficient development of new drugs.

See all the articles in this CEBP Focus section, "Biomarkers, Biospecimens, and New Technologies in Molecular Epidemiology."

Cancer Epidemiol Biomarkers Prev; 23(12); 2688–93. ©2014 AACR.

Background: To better understand colorectal cancer etiology and prognosis, archived surgical tissues were collected from Cancer Prevention Study II (CPS-II) Nutrition Cohort participants who were diagnosed with colorectal cancer. Herein, the methodology for this collection is described to help inform other efforts to collect tissues.

Methods: The main components to accruing tissue were: (i) obtaining consent from participants or next-of-kin; (ii) contacting hospitals to request materials; and (iii) pathology review and laboratory processing.

Results: In CPS-II, we identified 3,643 participants diagnosed with colorectal cancer between 1992/1993 and 2009. Of these, tissue could not be sought from cases verified through state cancer registry linkage (N = 1,622), because of insufficient information on tissue location. We sought tissue from the 2,021 cases verified using medical records, and received tissue from 882. When hospitals were contacted within 10 years of diagnosis, we received 87% of tissue materials; beyond that 10-year mark, we received 32%. Compared with the 2,761 colorectal cancer cases without tissue, the 882 cases with tissue were more likely to be alive, diagnosed more recently during follow-up, and had less-advanced staged disease. Cases with and without tissues were similar with respect to age at diagnosis, smoking, body mass index, physical activity, and other epidemiologic factors.

Conclusions: Some of the most important elements in forming a tissue repository included having the cases' hospital contact and surgical accession information as well as contacting patients/next-of-kin and hospitals within 10 years of surgery.

Impact: This tissue repository will serve as an important resource for colorectal cancer studies.

See all the articles in this CEBP Focus section, "Biomarkers, Biospecimens, and New Technologies in Molecular Epidemiology."

Cancer Epidemiol Biomarkers Prev; 23(12); 2694–702. ©2014 AACR.

Background: Nails contain genomic DNA that can be used for genetic analyses, which is attractive for large epidemiologic studies that have collected or are planning to collect nail clippings. Study participants will more readily participate in a study when asked to provide nail samples than when asked to provide a blood sample. In addition, nails are easy and cheap to obtain and store compared with other tissues.

Methods: We describe our findings on toenail DNA in terms of yield, quality, genotyping a limited set of SNPs with the Sequenom MassARRAY iPLEX platform and high-density genotyping with the Illumina HumanCytoSNP_FFPE-12 DNA array (>262,000 markers). We discuss our findings together with other studies on nail DNA and we compare nails and other frequently used tissue samples as DNA sources.

Results: Although nail DNA is considerably degraded, genotyping a limited set of SNPs with the Sequenom MassARRAY iPLEX platform (average sample call rate, 97.1%) and high-density genotyping with the Illumina HumanCytoSNP_FFPE chip (average sample call rate, 93.8%) were successful.

Conclusions: Nails are a suitable source of DNA for genotyping in large-scale epidemiologic studies, provided that methods are used that are suitable or optimized for degraded DNA. For genotyping through (next generation) sequencing where DNA degradation is less of an issue, nails may be an even more attractive DNA source, because it surpasses other sources in terms of ease and costs of obtaining and storing the samples.

Impact: It is worthwhile to consider nails as a source of DNA for genotyping in large-scale epidemiologic studies.

See all the articles in this CEBP Focus section, "Biomarkers, Biospecimens, and New Technologies in Molecular Epidemiology."

Cancer Epidemiol Biomarkers Prev; 23(12); 2703–12. ©2014 AACR.

Childhood brain tumors are the most common pediatric solid tumor and include several histologic subtypes. Although progress has been made in improving survival rates for some subtypes, understanding of risk factors for childhood brain tumors remains limited to a few genetic syndromes and ionizing radiation to the head and neck. In this report, we review descriptive and analytical epidemiology childhood brain tumor studies from the past decade and highlight priority areas for future epidemiology investigations and methodological work that is needed to advance our understanding of childhood brain tumor causes. Specifically, we summarize the results of a review of studies published since 2004 that have analyzed incidence and survival in different international regions and that have examined potential genetic, immune system, developmental and birth characteristics, and environmental risk factors. Cancer Epidemiol Biomarkers Prev; 23(12); 2716–36. ©2014 AACR.

Both targeted and genome-wide studies have revealed genetic associations for susceptibility, prognosis, and treatment-induced secondary malignancies and toxicities in classical Hodgkin lymphoma (cHL). This review gives a systematic and comprehensive overview of significant associations and places them into a biologic context. The strongest susceptibility polymorphisms have been found for the human leukocyte antigen (HLA) genes. These associations are specific for cHL overall or for subgroups based on tumor cell Epstein–Barr virus (EBV) status. These findings strongly suggest that EBV-specific immune responses influence cHL susceptibility in EBV+ cHL and that immune responses targeting other tumor-associated antigens are important in EBV cHL. Accordingly, most of the numerous other susceptibility loci map to genes that affect functionality of the immune system, underscoring the crucial role of the immune system in cHL development. The number of association studies on cHL prognosis is limited with one consistent association for the drug-metabolizing UGT1A1 gene. PRDM1 is associated with radiation-induced secondary malignancies and a small number of genes are associated with treatment-related toxicities. In conclusion, most loci showing genetic associations in cHL harbor genes with a potential functional relevance for cHL susceptibility. Cancer Epidemiol Biomarkers Prev; 23(12); 2737–47. ©2014 AACR.

Background: Physical activity (PA) is modifiable and linked to decreased breast cancer risk but its impact has not been investigated among indigenous African populations.

Methods: From 2011 to 2013, 558 cases and 1,014 controls were recruited into the African Breast Cancer Study in Nigeria, Cameroon, and Uganda, and completed a culturally tailored PA questionnaire that assesses habitual PA the year before diagnosis/interview. PA sub-scores (housework, occupational, and leisure PA) and a total PA score were calculated (metabolic equivalent of task, MET-hours/day). Multiple logistic regressions were performed, adjusting for age, body mass index (BMI), study sites, and menopausal status. The models were then stratified by BMI and study site, respectively.

Results: The overall PA score among controls (17.8 MET-hours/day on average) was mainly composed by housework PA and occupational PA with little leisure PA (7.0, 10.3, and 0.5 MET-hours/day, respectively). Multivariable analyses showed that PA was significantly associated with reduced breast cancer risk in both pre- and postmenopausal women (up to 60% risk reduction), with a dose-responsive relationship (Ptrend < 0.001). The inverse association was strong among lean women, less strong but still significant among overweight women, but not existing among obese women. The inverse association held for all intensity-level and domains of PA.

Conclusions: PA of African women mainly consists of housework and work-related activities. The preliminary data show that PA may be significantly associated with reduced breast cancer risk.

Impact: An inverse association between PA and breast cancer risk was observed among indigenous African women, a unique and understudied population. Cancer Epidemiol Biomarkers Prev; 23(12); 2748–56. ©2014 AACR.

Background: Organized human papillomavirus (HPV) vaccination was introduced in Sweden in 2012. On-demand vaccination was in effect from 2006 to 2011. We followed the HPV prevalences in Southern Sweden from 2008 to 2013.

Methods: Consecutive, anonymized samples from the Chlamydia trachomatis screening were analyzed for HPV DNA for two low-risk types and 14 high-risk types using PCR with genotyping using mass spectrometry. We analyzed 44,146 samples in 2008, 5,224 in 2012, and 5,815 in 2013.

Results: Registry-determined HPV vaccination coverages of the population in Southern Sweden increased mainly among 13- to 22-year-old women. Most analyzed samples contained genital swabs from women and the HPV6 prevalence in these samples decreased from 7.0% in 2008 to 4.2% in 2013 [–40.0%; P < 0.0005 (2 test)]. HPV16 decreased from 14.9% to 8.7% (–41.6%; P < 0.0005) and HPV18 decreased from 7.9% to 4.3% (–45.6%; P < 0.0005) among 13- to 22-year-old women. There were only small changes in vaccination coverage among 23- to 40-year-old women. In this age group, HPV18 decreased marginally (–19.6%; P = 0.04) and there were no significant changes for HPV6 or HPV16. Two nonvaccine HPV types (HPV52 and HPV56) were increased among 13- to 22-year-old women, both in 2012 and 2013.

Conclusions: A major reduction of HPV6, 16, and 18 prevalences is seen in the age groups with a concomitant increase in HPV vaccination coverage. The minor changes seen for nonvaccine types will require further investigation.

Impact: Monitoring of type-specific HPV prevalences may detect early effects of HPV vaccination. Cancer Epidemiol Biomarkers Prev; 23(12); 2757–64. ©2014 AACR.

Background: Terminal duct lobular units (TDLU) are the predominant source of breast cancers. Lesser degrees of age-related TDLU involution have been associated with increased breast cancer risk, but factors that influence involution are largely unknown. We assessed whether circulating hormones, implicated in breast cancer risk, are associated with levels of TDLU involution using data from the Susan G. Komen Tissue Bank (KTB) at the Indiana University Simon Cancer Center (2009–2011).

Methods: We evaluated three highly reproducible measures of TDLU involution, using normal breast tissue samples from the KTB (n = 390): TDLU counts, median TDLU span, and median acini counts per TDLU. RRs (for continuous measures), ORs (for categorical measures), 95% confidence intervals (95% CI), and Ptrends were calculated to assess the association between tertiles of estradiol, testosterone, sex hormone–binding globulin (SHBG), progesterone, and prolactin with TDLU measures. All models were stratified by menopausal status and adjusted for confounders.

Results: Among premenopausal women, higher prolactin levels were associated with higher TDLU counts (RRT3vsT1:1.18; 95% CI: 1.07–1.31; Ptrend = 0.0005), but higher progesterone was associated with lower TDLU counts (RRT3vsT1: 0.80; 95% CI: 0.72–0.89; Ptrend < 0.0001). Among postmenopausal women, higher levels of estradiol (RRT3vsT1:1.61; 95% CI: 1.32–1.97; Ptrend < 0.0001) and testosterone (RRT3vsT1: 1.32; 95% CI: 1.09–1.59; Ptrend = 0.0043) were associated with higher TDLU counts.

Conclusions: These data suggest that select hormones may influence breast cancer risk potentially through delaying TDLU involution.

Impact: Increased understanding of the relationship between circulating markers and TDLU involution may offer new insights into breast carcinogenesis. Cancer Epidemiol Biomarkers Prev; 23(12); 2765–73. ©2014 AACR.

Background: Volatile organic compounds (VOC) from tobacco smoke are associated with cancer, cardiovascular, and respiratory diseases. The objective of this study was to characterize the exposure of nonsmokers to VOCs from secondhand smoke (SHS) in vehicles using mercapturic acid metabolites.

Methods: Fourteen nonsmokers were individually exposed in the backseat to one hour of SHS from a smoker seated in the driver's seat who smoked three cigarettes at 20-minute intervals in a stationary car with windows opened by 10 cm. Baseline and 0- to 8-hour postexposure mercapturic acid metabolites of nine VOCs were measured in urine. Air-to-urine VOC ratios were estimated on the basis of respirable particulate matter (PM2.5) or air nicotine concentration, and lifetime excess risk (LER) of cancer death from exposure to acrylonitrile, benzene, and 1,3-butadiene was estimated for adults.

Results: The greatest increase in 0- to 8-hour postexposure concentrations of mercapturic acids from baseline was MHBMA-3 (parent, 1,3-butadiene; 2.1-fold), then CNEMA (acrylonitrile; 1.7-fold), PMA (benzene; 1.6-fold), MMA (methylating agents; 1.6-fold), and HEMA (ethylene oxide; 1.3-fold). The LER of cancer death from exposure to acrylonitrile, benzene, and 1,3-butadiene in SHS for 5 hours a week ranged from 15.5 x 10–6 to 28.1 x 10–6 for adults, using air nicotine and PM2.5 to predict air VOC exposure, respectively.

Conclusion: Nonsmokers have significant intake of multiple VOCs from breathing SHS in cars, corresponding to health risks that exceed the acceptable level.

Impact: Smoking in cars may be associated with increased risks of cancer, respiratory, and cardiovascular diseases among nonsmokers. Cancer Epidemiol Biomarkers Prev; 23(12); 2774–82. ©2014 AACR.

Background: We aimed to systematically summarize the diagnostic and prognostic value of circulating/tissue miR21 in patients with colorectal cancer.

Methods: An original study was conducted to explore the potential value of circulating miR21 in colorectal cancer diagnosis and tissue miR21 in colorectal cancer prognosis. PUBMED and EMBASE were searched (to August, 2013) to identify eligible studies. To explore the diagnostic performance of circulating miR21, meta-analysis methods were used to pool sensitivity, specificity, positive and negative likelihood ratio, diagnostic OR and to construct a summary ROC curve. For prognostic meta-analysis, study-specific HRs of tissue miR21 for survival were summarized. Subgroup and sensitivity analyses were applied to explore heterogeneity.

Results: Finally, 14 studies (including our study) were included in the meta-analyses. The pooled sensitivity, specificity, and AUC of circulating miR21 were 0.76 [95% confidence interval (CI), 0.59–0.88], 0.81 (95% CI, 0.76–0.85), and 0.81 (95% CI, 0.78–0.85) in diagnosing colorectal cancer. Patients with higher expression of tissue miR21 had significant inferior overall survival (OS; pooled HR, 1.56; 95% CI, 1.16–2.11) and disease-free survival (DFS; pooled HR, 1.35; 95% CI, 1.08–1.69). The individual participant data (IPD) meta-analysis demonstrated that tissue miR21 level was independently associated with worse colorectal cancer OS (HR, 1.69; 95% CI, 1.07–2.67; P = 0.023), whereas this association seems to be confined to males (P = 0.007) but not for females (P = 0.845).

Conclusions: Circulating miR21 level has potential value for colorectal cancer early detection, whereas high tissue miR21 level is associated with adverse colorectal cancer prognosis.

Impact: miR21 is a promising biomarker for early detection and prognosis of colorectal cancer. Cancer Epidemiol Biomarkers Prev; 23(12); 2783–92. ©2014 AACR.

Background: Benzene is a human hematotoxicant and a leukemogen that causes lymphohematopoietic cancers, especially acute myelogenous leukemia. We investigated uptake of benzene in hookah smokers and non-smokers attending hookah social events in naturalistic settings where hookah tobacco was smoked exclusively.

Methods: We quantified S-phenylmercapturic acid (SPMA), a metabolite of benzene, in the urine of 105 hookah smokers and 103 non-smokers. Participants provided spot urine samples the morning of and the morning after attending an indoor hookah-only smoking social event at a hookah lounge or in a private home.

Results: Urinary SPMA levels in hookah smokers increased significantly following a hookah social event (P < 0.001). This increase was 4.2 times higher after hookah lounge events (P < 0.001) and 1.9 times higher after home events (P = 0.003). In non-smokers, urinary SPMA levels increased 2.6 times after hookah lounge events (P = 0.055); however, similar urinary SPMA levels were detected before and after home events, possibly indicating chronic exposure to benzene (P = 0.933).

Conclusions: Our data provide the first evidence for uptake of benzene in hookah smokers and non-smokers exposed to hookah tobacco secondhand smoke at social events in private homes compared with their counterparts in hookah lounges. Hookah tobacco smoke is a source of benzene exposure, a risk factor for leukemia.

Impact: Because there is no safe level of exposure to benzene, our results call for interventions to reduce or prevent hookah tobacco use, regulatory actions to limit hookah-related exposure to toxicants including benzene, initiate labeling of hookah-related products, and include hookah smoking in clean indoor air legislation. Cancer Epidemiol Biomarkers Prev; 23(12); 2793–809. ©2014 AACR.

Background: Breast tissue composition (epithelium, non-fatty stroma, and adipose) changes qualitatively and quantitatively throughout the lifespan, and may mediate relationships between risk factors and breast cancer initiation. We sought to identify relationships between tissue composition, risk factors, tumor characteristics, and gene expression.

Methods: Participants were 146 patients from the Polish Breast Cancer Study, with data on risk factor and clinicopathological characteristics. Benign breast tissue composition was evaluated using digital image analysis of histologic sections. Whole-genome microarrays were performed on the same tissue blocks.

Results: Mean epithelial, non-fatty stromal, and adipose proportions were 8.4% (SD = 4.9%), 27.7% (SD = 24.0%), and 64.0% (SD = 24.0%), respectively. Among women <50 years old, stroma proportion decreased and adipose proportion increased with age, with approximately 2% difference per year (P < 0.01). The variation in epithelial proportion with age was modest (0.1% per year). Higher epithelial proportion was associated with obesity (7.6% in nonobese vs. 10.1% in obese; P = 0.02) and with poorly differentiated tumors (7.8% in well/moderate vs. 9.9% in poor; P = 0.05). Gene expression signatures associated with epithelial and stromal proportion were identified and validated. Stroma-associated genes were in metabolism and stem cell maintenance pathways, whereas epithelial genes were enriched for cytokine and immune response pathways.

Conclusions: Breast tissue composition was associated with age, body mass index, and tumor grade, with consequences for breast gene expression.

Impact: Breast tissue morphologic factors may influence breast cancer etiology. Composition and gene expression may act as biomarkers of breast cancer risk and progression. Cancer Epidemiol Biomarkers Prev; 23(12); 2810–8. ©2014 AACR.

Background: The effect of neighborhood and healthcare access factors on cancer outcomes among patients enrolled in navigator programs is not clearly understood. This study assessed associations between: (i) neighborhood factors and diagnostic time to resolution (TTR) and (ii) geographic access and TTR following an abnormal breast or cervical cancer screening test among women participating in the Ohio Patient Navigator Research Program (OPNRP).

Methods: Patient (demographic, socioeconomic status, home-to-clinic distance) and neighborhood (deprivation, racial segregation) characteristics of 801 women living in one of 285 census tracts (CT) in greater Columbus, Ohio were examined. Randomization to receive navigation occurred at the clinic level. Multilevel Cox regression and spatial analysis were used to estimate effects of various factors on TTR and assess model assumptions, respectively.

Results: TTR increased as neighborhood deprivation increased. After adjustment for age, friend social support, education, and healthcare status, the TTR among women living in a neighborhood with a moderate median household income (between $36,147 and $53,099) was shorter compared with women living in low median household income neighborhoods (<$36,147; P < 0.05). There is little evidence that unmeasured confounders are geographically patterned.

Conclusions: Increased neighborhood socioeconomic deprivation was associated with longer TTR following an abnormal breast or cervical cancer screening test.

Impact: These results highlight the need for addressing patient- and neighborhood-level factors to reduce cancer disparities among underserved populations. Cancer Epidemiol Biomarkers Prev; 23(12); 2819–28. ©2014 AACR.

Background: Melanocytic nevi (moles) and freckles are well known biomarkers of melanoma risk, and they are influenced by similar UV light exposures and genetic susceptibilities to those that increase melanoma risk. Nevertheless, the selective interactions between UV exposures and nevus and freckling genes remain largely undescribed.

Methods: We conducted a longitudinal study from ages 6 through 10 years in 477 Colorado children who had annual information collected for sun exposure, sun protection behaviors, and full body skin exams. MC1R and HERC2/OCA2 rs12913832 were genotyped and linear mixed models were used to identify main and interaction effects.

Results: All measures of sun exposure (chronic, sunburns, and waterside vacations) contributed to total nevus counts, and cumulative chronic exposure acted as the major driver of nevus development. Waterside vacations strongly increased total nevus counts in children with rs12913832 blue eye color alleles and facial freckling scores in those with MC1R red hair color variants. Sunburns increased the numbers of larger nevi (≥2 mm) in subjects with certain MC1R and rs12913832 genotypes.

Conclusions: Complex interactions between different UV exposure profiles and genotype combinations determine nevus numbers and size, and the degree of facial freckling.

Impact: Our findings emphasize the importance of implementing sun-protective behavior in childhood regardless of genetic make-up, although children with particular genetic variants may benefit from specifically targeted preventive measures to counteract their inherent risk of melanoma. Moreover, we demonstrate, for the first time, that longitudinal studies are a highly powered tool to uncover new gene–environment interactions that increase cancer risk. Cancer Epidemiol Biomarkers Prev; 23(12); 2829–39. ©2014 AACR.

Background: Epidemiologic studies examining circulating levels of inflammatory markers in relation to obesity and physical inactivity may aid in our understanding of the role of inflammation in obesity-related cancers. However, previous studies on this topic have focused on a limited set of markers.

Methods: We evaluated associations between body mass index (BMI) and vigorous physical activity level, based on self-report, and serum levels of 78 inflammation-related markers. Markers were measured using a bead-based multiplex method among 1,703 men and women, ages 55–74 years, and with no prior history of cancer at blood draw, and selected for case–control studies nested within the Prostate, Lung, Ovarian, and Colorectal Cancer Screening Trial. Analyses were adjusted for age, sex, smoking, case–control study, physical activity, and BMI.

Results: Twelve markers were positively associated with BMI after FDR correction. ORs and 95% confidence interval (CI) for highest versus lowest levels of CCL2/MCP-1, CXCL5/ENA-78, sTNFRII, CXCL10/IP-10, CXCL6/GCP2, CCL13/MCP-4, amylin, CRP, C-peptide, CCL19/MIP-3b, insulin, and leptin were: 1.50 (1.14–1.98), 1.52 (1.12–2.05), 1.61 (1.17–2.20), 1.69 (1.25–2.28), 1.74 (1.24–2.44), 1.75 (1.22–2.50), 1.91 (1.31–2.78), 2.41 (1.36–4.25), 2.78 (1.83–4.24), 3.30 (2.28–4.78), 4.05 (2.51–6.55), and 50.03 (19.87–125.99) per 5 kg/m2, respectively. Only CXCL12/SDF-1a was associated with physical activity (≥3 vs. <1 h/wk; OR, 3.28; 95% CI, 1.55–6.94) after FDR correction.

Conclusions: BMI was associated with a wide range of circulating markers involved in the inflammatory response.

Impact: This cross-sectional analysis identified serum markers could be considered in future studies aimed at understanding the underlying mechanisms linking inflammation with obesity and obesity-related cancers. Cancer Epidemiol Biomarkers Prev; 23(12); 2840–9. ©2014 AACR.

Background: The winning model of the Sage Bionetworks/DREAM Breast Cancer Prognosis Challenge made use of several molecular features, called attractor metagenes, as well as another metagene defined by the average expression level of the two genes FGD3 and SUSD3. This is a follow-up study toward developing a breast cancer prognostic test derived from and improving upon that model.

Methods: We designed a feature selector facility calculating the prognostic scores of combinations of features, including those that we had used earlier, as well as those used in existing breast cancer biomarker assays, identifying the optimal selection of features for the test.

Results: The resulting test, called BCAM (Breast Cancer Attractor Metagenes), is universally applicable to all clinical subtypes and stages of breast cancer and does not make any use of breast cancer molecular subtype or hormonal status information, none of which provided additional prognostic value. BCAM is composed of several molecular features: the breast cancer–specific FGD3–SUSD3 metagene, four attractor metagenes present in multiple cancer types (CIN, MES, LYM, and END), three additional individual genes (CD68, DNAJB9, and CXCL12), tumor size, and the number of positive lymph nodes.

Conclusions: Our analysis leads to the unexpected and remarkable suggestion that ER, PR, and HER2 status, or molecular subtype classification, do not provide additional prognostic value when the values of the FGD3–SUSD3 and attractor metagenes are taken into consideration.

Impact: Our results suggest that BCAM's prognostic predictions show potential to outperform those resulting from existing breast cancer biomarker assays. Cancer Epidemiol Biomarkers Prev; 23(12); 2850–6. ©2014 AACR.

Background: The natural history of human papillomavirus (HPV) infection in men on a population base has rarely been studied in general, particularly among Chinese men.

Methods: A total of 1,286 men ages 25 to 65 years from rural China were enrolled during 2009–2010 and their genital HPV infection status was assessed biannually for up to seven visits using PCR and sequencing methods. Prevalence analysis was performed among men with at least one valid HPV result (N = 1,279) and men with at least two consecutive HPV results (N = 1,059) were included in incidence and clearance analyses (median follow-up time, 31.8 months; interquartile range, 15.4–37.9 months).

Results: The prevalence and incidence of any HPV type, oncogenic, and nononcogenic HPV were 17.8%, 6.4%, 12.4%, and 14.6, 4.9, 10.8 per 1,000 person months, respectively. The median duration of infection with any HPV type, oncogenic, and nononcogenic HPV was 11.5, 6.8, and 11.5 months, respectively. The number of lifetime sexual partners was consistently associated with increased risk of prevalent and incident infection of HPV. Men ages 25 to 50 years had a higher incidence and longer duration of HPV infection than older men (51–65 years).

Conclusions and Impact: This epidemiologic investigation provides basic information of genital HPV infection among the Chinese male population; these data are crucial for the consideration of primary strategies against HPV-related carcinoma in the Chinese male and female population. Cancer Epidemiol Biomarkers Prev; 23(12); 2857–65. ©2014 AACR.

Background: Levels of the cyclooxygenase 2 (COX2) enzyme are elevated in breast cancer tissue, and most COX2 effects are believed to be mediated through overproduction of prostaglandin E2 (PGE2). We evaluated associations between the primary urinary metabolite of PGE2 (PGE-M) and breast cancer risk.

Methods: A nested case–control study of 504 cases and 1,082 controls was conducted using data from the Shanghai Women's Health Study, a large population-based prospective cohort study of 74,941 Chinese women. Urinary PGE-M was measured using a liquid chromatography/tandem mass spectrometric method. Logistic regression estimated odds ratios (OR) and 95% confidence intervals (95% CI) with adjustment for potential confounders.

Results: Overall, no association between urinary PGE-M and breast cancer was detected. However, a suggestive positive association was found among postmenopausal women. In particular, a clear dose–response relationship between urinary PGE-M and breast cancer was observed among postmenopausal women with a body mass index (BMI) < 25 kg/m2 (Plinear trend = 0.005). Among these women, risk of breast cancer increased from 1.00 (reference) to 1.06 (95% CI, 0.56–1.99), 1.50 (95% CI, 0.79–2.83), and 2.32 (95% CI, 1.24–4.41) for the lowest to highest quartiles of PGE-M, and such associations were stronger among those who were diagnosed with cancer within the first four years of sample collection. No apparent association was observed among overweight postmenopausal women (BMI ≥ 25 kg/m2).

Conclusion: High urinary PGE-M level was associated with elevated risk of breast cancer among normal weight, postmenopausal women.

Impact: Urinary PGE-M level may be useful for breast cancer risk assessment among normal weight, postmenopausal women. Cancer Epidemiol Biomarkers Prev; 23(12); 2866–73. ©2014 AACR.

Background: Measurement error in self-reported sugars intake may be obscuring the association between sugars and cancer risk in nutritional epidemiologic studies.

Methods: We used 24-hour urinary sucrose and fructose as a predictive biomarker for total sugars, to assess measurement error in self-reported sugars intake. The Nutrition and Physical Activity Assessment Study (NPAAS) is a biomarker study within the Women's Health Initiative (WHI) Observational Study that includes 450 postmenopausal women ages 60 to 91 years. Food Frequency Questionnaires (FFQ), four-day food records (4DFR), and three 24-hour dietary recalls (24HRs) were collected along with sugars and energy dietary biomarkers.

Results: Using the biomarker, we found self-reported sugars to be substantially and roughly equally misreported across the FFQ, 4DFR, and 24HR. All instruments were associated with considerable intake- and person-specific bias. Three 24HRs would provide the least attenuated risk estimate for sugars (attenuation factor, AF = 0.57), followed by FFQ (AF = 0.48) and 4DFR (AF = 0.32), in studies of energy-adjusted sugars and disease risk. In calibration models, self-reports explained little variation in true intake (5%–6% for absolute sugars and 7%–18% for sugars density). Adding participants' characteristics somewhat improved the percentage variation explained (16%–18% for absolute sugars and 29%–40% for sugars density).

Conclusions: None of the self-report instruments provided a good estimate of sugars intake, although overall 24HRs seemed to perform the best.

Impact: Assuming the calibrated sugars biomarker is unbiased, this analysis suggests that measuring the biomarker in a subsample of the study population for calibration purposes may be necessary for obtaining unbiased risk estimates in cancer association studies. Cancer Epidemiol Biomarkers Prev; 23(12); 2874–83. ©2014 AACR.

Background: We previously developed a prognostic classifier using the expression levels of BRCA1, HIF1A, DLC1, and XPO1 that identified stage I lung adenocarcinoma patients with a high risk of relapse. That study evaluated patients in five independent cohorts from various regions of the world. In an attempt to further validate the classifier, we have used a meta-analysis–based approach to study 12 cohorts consisting of 1,069 tumor–node–metastasis stage I lung adenocarcinoma patients from every suitable, publically available dataset.

Methods: Cohorts were obtained through a systematic search of public gene expression datasets. These data were used to calculate the risk score using the previously published 4-gene risk model. A fixed effect meta-analysis model was used to generate a pooled estimate for all cohorts.

Results: The classifier was associated with prognosis in 10 of the 12 cohorts (P < 0.05). This association was highly consistent regardless of the ethnic diversity or microarray platform. The pooled estimate demonstrated that patients classified as high risk had worse overall survival for all stage I [HR, 2.66; 95% confidence interval (CI), 1.93–3.67; P < 0.0001] patients and in stratified analyses of stage IA (HR, 2.69; 95% CI, 1.66–4.35; P < 0.0001) and stage IB (HR, 2.69; 95% CI, 1.74–4.16; P < 0.0001) patients.

Conclusions: The 4-gene classifier provides independent prognostic stratification of stage IA and stage IB patients beyond conventional clinical factors.

Impact: Our results suggest that the 4-gene classifier may assist clinicians in decisions about the postoperative management of early-stage lung adenocarcinoma patients. Cancer Epidemiol Biomarkers Prev; 23(12); 2884–94. ©2014 AACR.

Background: Disproportionally low retention of minority populations can adversely affect the generalizability of clinical research trials. We determine the overall retention rates for White and Black participants from the Selenium and Vitamin E Cancer Prevention Trial (SELECT) and explore participant and site characteristics associated with retention failure (study disengagement) for these groups.

Methods: A secondary analysis of 28,118 White (age ≥55), and 4,322 Black (age ≥ 50) SELECT participants used multivariate Cox regression to estimate overall retention rates and to calculate HRs and 95% confidence intervals (CI).

Results: Blacks had higher age-adjusted risk of disengagement than Whites (HR, 1.92; 95% CI, 1.77–2.08). Among Black participants, those ages 50 to 54 were at three times the risk of disengagement than those ≥65 years of age (HR, 3.61; 95% CI, 2.41–5.41). Blacks age ≥65 had 1.6 times the risk of disengagement than Whites age ≥65 (HR, 1.60; 95% CI, 1.38–1.87). By 6 years after randomization, 84% of Whites and 69% of Blacks remained engaged in the study. Current smoking status was an independent risk factor for study disengagement for both White and Black participants. For both groups, sites whose staffs missed SELECT training sessions or who received SELECT Retention and Adherence grants were associated with increased and decreased disengagement risks, respectively.

Conclusions: SELECT retention was disproportionately lower for Blacks than for Whites.

Impact: The observed difference in retention rates for Blacks and Whites and factors identified by race for study disengagement in SELECT may inform retention efforts for future long-term, cancer prevention trials. Cancer Epidemiol Biomarkers Prev; 23(12); 2895–905. ©2014 AACR.

Background: Cigar consumption is increasing in the United States, but little information is available about exposure to toxic constituents from cigar smoking.

Methods: We conducted a cross-sectional analysis of biomarkers of tobacco exposure among 25,522 participants from the National Health and Nutrition Examination Survey (NHANES, 1999–2012). The biomarkers analyzed were serum cotinine, urinary 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), blood lead, blood cadmium, and urinary arsenic. We calculated geometric mean concentrations for each biomarker by tobacco use category and geometric mean ratios controlling for demographic factors.

Results: Cigar smokers had higher cotinine, NNAL, and lead concentrations than nontobacco users. The geometric mean concentration [95% confidence interval (CI)] of cotinine for primary cigar smokers (i.e., current cigar/never cigarette smokers) was 6.2 (4.2–9.2) ng/mL versus 0.045 (0.043–0.048) ng/mL for nontobacco users, and the NNAL concentration was 19.1 (10.6–34.3) pg/mg creatinine for primary cigar smokers versus 1.01 (0.95–1.07) pg/mg creatinine for nontobacco users. Secondary cigar smokers (i.e., current cigar/former cigarette smokers) and dual cigar/cigarette smokers had higher cadmium concentrations than nontobacco users. Cigar smoking was associated with significantly higher concentrations of cotinine, NNAL, cadmium, and lead, after adjusting for demographic factors. Secondary cigar smokers had significantly higher cotinine and NNAL concentrations than primary cigar smokers. The NNAL concentrations in daily cigar smokers were comparable with those in daily cigarette smokers.

Conclusions: Cigar smokers have higher concentrations of several toxic and carcinogenic substances than nontobacco users.

Impact: Our results are consistent with epidemiologic evidence demonstrating cigar smoking as a cause of disease and premature death. Cancer Epidemiol Biomarkers Prev; 23(12); 2906–15. ©2014 AACR.

Background: Aversion to "ambiguity"—uncertainty about the reliability, credibility, or adequacy of information—about medical tests and treatments is an important psychological response that varies among individuals, but little is known about its nature and extent. The purpose of this study was to examine how individual-level ambiguity aversion relates to important health cognitions related to different cancer screening tests.

Methods: A survey of 1,074 adults, ages 40 to 70 years, was conducted in four integrated U.S. healthcare systems. The Ambiguity Aversion in Medicine (AA-Med) scale, a measure of individual differences in aversion to ambiguity (AA) about medical tests and treatments, was administered along with measures of several cancer screening-related cognitions: perceived benefits and harms of colonoscopy, mammography, and PSA screening, and ambivalence and future intentions regarding these tests. Multivariable analyses were conducted to assess the associations between AA-Med scores and cancer screening cognitions.

Results: Individual-level AA as assessed by the AA-Med scale was significantly associated (P < 0.05) with lower perceived benefits, greater perceived harms, and greater ambivalence about all three screening tests, and lower intentions for colonoscopy but not mammography or PSA screening.

Conclusion: Individual-level AA is broadly and simultaneously associated with various pessimistic cognitive appraisals of multiple cancer screening tests. The breadth of these associations suggests that the influence of individual-level AA is insensitive to the degree and nonspecific with respect to the causes of ambiguity.

Impact: Individual-level AA constitutes a measurable, wide-ranging cognitive bias against medical intervention, and more research is needed to elucidate its mechanisms and effects. Cancer Epidemiol Biomarkers Prev; 23(12); 2916–23. ©2014 AACR.

Background: The Women's Health Initiative (WHI) low-fat (20% kcal) dietary modification (DM) trial (1993–2005) demonstrated a nonsignificant reduction in breast cancer, a nominally significant reduction in ovarian cancer, and no effect on other cancers (mean 8.3 years intervention). Consent to nonintervention follow-up was 83% (n = 37,858). This analysis was designed to assess postintervention cancer risk in women randomized to the low-fat diet (40%) versus usual diet comparison (60%).

Methods: Randomized, controlled low-fat diet intervention for prevention of breast and colorectal cancers conducted in 48,835 postmenopausal U.S. women, ages 50 to 79 years at 40 U.S. sites. Outcomes included total invasive cancer, breast cancer, and colorectal cancer, and cancer-specific and overall mortality.

Results: There were no intervention effects on invasive breast or colorectal cancer, other cancers, or cancer-specific or overall mortality during the postintervention period or the combined intervention and follow-up periods. For invasive breast cancer, the hazard ratios (HR) and 95% confidence interval (CI) were 0.92 (0.84–1.01) during intervention, 1.08 (0.94–1.24) during the postintervention period, and 0.97 (0.89–1.05) during cumulative follow-up. A reduced risk for estrogen receptor positive/progesterone receptor–negative tumors was demonstrated during follow-up. In women with higher baseline fat intake (quartile), point estimates of breast cancer risk were HR, 0.76 (95% CI, 0.62–0.92) during intervention versus HR, 1.11 (95% CI, 0.84–1.4) during postintervention follow-up (Pdiff = 0.03).

Conclusions: Dietary fat intake increased postintervention in intervention women; no long-term reduction in cancer risk or mortality was shown in the WHI DM trial.

Impact: Dietary advisement to reduce fat for cancer prevention after menopause generally was not supported by the WHI DM trial. Cancer Epidemiol Biomarkers Prev; 23(12); 2924–35. ©2014 AACR.

Background: Studies suggest that obesity is associated with lower risk of prostate cancer but more aggressive cancers. As obesity lowers PSA levels, these observations may be influenced by detection bias. We examined the association between obesity and risk of low- and high-grade prostate cancer in REDUCE, in which biopsies were largely independent of PSA.

Methods: The REDUCE study tested dutasteride for prostate cancer risk reduction in men with a PSA of 2.5 to 10.0 ng/mL and a negative biopsy. Study participants included 6,729 men who underwent at least one on-study biopsy. The association between baseline body mass index (BMI <25 kg/m2 normal weight; 25–29.9 kg/m2 overweight; and ≥30 kg/m2 obese) and risk of high-grade (Gleason ≥7) or low-grade prostate cancer (Gleason <7) versus no prostate cancer was examined using multinomial logistic regression.

Results: Overall, 1,739 men (27%) were normal weight, 3,384 (53%) overweight, and 1,304 (20%) were obese. Obesity was associated with lower risk of low-grade prostate cancer in both univariable (OR, 0.74; P = 0.001) and multivariable analyses (OR, 0.79; P = 0.01). In univariable analysis, obesity was not associated with high-grade prostate cancer (OR, 1.08; P = 0.50). However, in multivariable analysis, obesity was associated with increased risk of high-grade prostate cancer (OR, 1.28; P = 0.042). This analysis was not able to address how obesity may influence prostate cancer progression.

Conclusions: Obesity is associated with decreased risk of low-grade and increased risk of high-grade prostate cancer. These data provide further support to the hypothesis that obesity is associated with aggressive prostate cancer.

Impact: Obesity is linked with aggressive prostate cancer. Avoiding obesity may prevent the risk of developing high-grade prostate cancer. Cancer Epidemiol Biomarkers Prev; 23(12); 2936–42. ©2014 AACR.

Background: Alcohol consumption is a consistent risk factor for breast cancer, and evidence suggests premenopausal plasma hormones are associated with breast cancer.

Methods: Plasma concentrations of estradiol, estrone, estrone sulfate, testosterone, androstenedione, progesterone, prolactin, dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), and sex hormone–binding globulin (SHBG) were measured in samples collected in 1996–99. Average alcohol intake was calculated from semiquantitative food frequency questionnaires collected in 1995 and 1999. We used generalized linear models to calculate geometric mean hormone concentrations across alcohol categories and the percentage difference for the highest versus lowest category.

Results: Comparing women who consumed >20 g/d with nondrinkers, levels were 25.7% higher for luteal estrone (geometric mean, 106 vs. 84.5 pg/mL; Ptrend = 0.001), 27.2% higher for luteal estradiol (182 vs. 143 pg/mL; Ptrend = 0.006), and 16.8% higher for SHBG (85.6 vs. 73.3 nmol/L; Ptrend = 0.03); concentrations of free testosterone were 17.9% lower (0.16 vs. 0.20 ng/dL; Ptrend = 0.002). Women consuming >10 g/d compared with nondrinkers had 26.5% higher concentrations of follicular estrone sulfate (950 vs. 751 pg/mL; Ptrend = 0.04). We did not observe significant associations between alcohol and the other sex hormones evaluated. Significant positive associations were observed with beer intake, but not other alcohol types, for DHEA (Pinteraction = 0.003) and androstenedione (Pinteraction = 0.006).

Conclusion: Alcohol consumption was significantly positively associated with plasma luteal estrogen concentrations, but not with androgen levels, nor estrone or estradiol measured in the follicular phase.

Impact: Differences in premenopausal estrogen levels may contribute to the association between alcohol and breast cancer. Cancer Epidemiol Biomarkers Prev; 23(12); 2943–53. ©2014 AACR.

Oropharyngeal cancer (OPC) is more frequent in men than women mainly due to the heavier and longer duration of smoking in men. Human papillomavirus (HPV) has a role in the rising incidence of OPC in the United States and other high-income countries. To determine whether there is a difference in the proportion of HPV-attributable OPC between men and women, we systematically retrieved HPV prevalence data from 63 studies reporting separately on OPC by gender. The male/female (M/F) ratios of HPV prevalence in OPC across different countries and the corresponding M/F ratios of cumulative lung cancer risk (a proxy for smoking) were compared. The United States had the highest M/F ratios of HPV prevalence in OPC (1.5). The lowest M/F ratios (≤0.7) were found in Asia and some European countries (e.g., France). The countries in which the M/F ratio of HPV prevalence in OPC was ≥1.0 had the most similar lung cancer risks for men and women. When HPV prevalence data were applied to age-standardized OPC incidence rates in the United States, Australia, the United Kingdom, and France, the M/F ratio for the HPV-positive OPC incidence rates was rather stable (around 4) in all countries. In contrast, the M/F ratio for the HPV-negative OPC incidence rates reached 10.2 in France versus <3 elsewhere. We showed that HPV prevalence in OPC differs by gender and country mainly as a consequence of the vast international variation in male smoking habits. Nevertheless, HPV-positive OPC may affect men more heavily than women in different populations for reasons that are unclear. Cancer Epidemiol Biomarkers Prev; 23(12); 2954–8. ©2014 AACR.

We estimated the prevalence of oral human papillomavirus (HPV) and assessed risk factors among young heterosexual men participating in the HPV Infection and Transmission among Couples through Heterosexual Activity (HITCH) study. Oral and genital HPV samples were collected from 222 men and their female partners who were participating in the HITCH study, a longitudinal cohort on HPV transmission among heterosexual couples. Demographic and behavioral data were collected through self-administered computer questionnaires and biologic samples were tested with the Linear Array for HPV. Outcome measures were overall and type-specific prevalence of oral HPV. The prevalence of oral HPV among men was 7.2% and was higher among men who were ever smokers (12.2%), in nonmonogamous relationships (17.9%), or had a partner with oral (28.6%) and/or genital (11.5%) HPV infection. Moreover, prevalence increased with frequency of oral sex among men whose partner who had a genital infection with the same HPV type. Our results provide further evidence that oral HPV may be transmitted through either oral–oral or oral–genital routes. Cancer Epidemiol Biomarkers Prev; 23(12); 2959–64. ©2014 AACR.

Cancer cells expressing PD-1 ligands (PD-L1/PD-L2) inhibit immune-modulatory T-cell activation facilitating disease progression. Preliminary clinical trials exploring interruption of PD-1/PD-L1 signaling showed benefit in several cancer types. We analyzed the distribution of PD-1–positive tumor-infiltrating lymphocytes (TIL) and cancer cells' expression of PD-L1 in a molecularly profiled cohort of 437 malignancies (380 carcinomas, 33 sarcomas, and 24 melanomas). We showed that the presence of PD-1+ TILs significantly varied among cancer types (from 0% in extraskeletal myxoid chondrosarcomas to 93% in ovarian cancer), and was generally associated with the increased number of mutations in tumor cells (P = 0.029). Cancer cell expression of PD-L1 varied from absent (in Merkel cell carcinomas) to 100% (in chondro- and liposarcomas), but showed the inverse association with the number of detected mutations (P = 0.004). Both PD-1 and PD-L1 expression were significantly higher in triple-negative breast cancers (TNBC) than in non-TNBC (P < 0.001 and 0.017, respectively). Similarly, MSI-H colon cancers had higher PD-1 and PD-L1 expression than the microsatellite stable tumors (P = 0.002 and 0.02, respectively). TP53-mutated breast cancers had significantly higher PD-1 positivity than those harboring other driver mutations (e.g., PIK3CA; P = 0.002). In non–small cell lung cancer, PD-1/PD-L1 coexpression was identified in 8 cases (19%), which lacked any other targetable alterations (e.g., EGFR, ALK, or ROS1). Our study demonstrated the utility of exploring the expression of two potentially targetable immune checkpoint proteins (PD-1/PD-L1) in a substantial proportion of solid tumors, including some aggressive subtypes that lack other targeted treatment modalities. Cancer Epidemiol Biomarkers Prev; 23(12); 2965–70. ©2014 AACR.

Background: Calcium intake may reduce risk of colorectal cancer, but the mechanisms remain unclear. Studies of interaction between calcium intake and SNPs in calcium-related pathways have yielded inconsistent results.

Methods: To identify gene–calcium interactions, we tested interactions between approximately 2.7 million SNPs across the genome with self-reported calcium intake (from dietary or supplemental sources) in 9,006 colorectal cancer cases and 9,503 controls of European ancestry. To test for multiplicative interactions, we used multivariable logistic regression and defined statistical significance using the conventional genome-wide α = 5E–08.

Results: After accounting for multiple comparisons, there were no statistically significant SNP interactions with total, dietary, or supplemental calcium intake.

Conclusions: We found no evidence of SNP interactions with calcium intake for colorectal cancer risk in a large population of 18,509 individuals.

Impact: These results suggest that in genome-wide analysis common genetic variants do not strongly modify the association between calcium intake and colorectal cancer in European populations. Cancer Epidemiol Biomarkers Prev; 23(12); 2971–6. ©2014 AACR.

Background: We previously reported that higher levels of mitochondrial DNA copy number (mtDNA CN) were associated with lung cancer risk among male heavy smokers (i.e., ≥20 cigarettes per day) in the Alpha-Tocopherol Beta-Carotene (ATBC) study. Here, we present two additional prospective investigations nested in the Prostate, Lung, Colorectal, and Ovarian (PLCO) cancer screening trial and the Shanghai Women's Health Study (SWHS), and pooled with previously published data from ATBC.

Materials: All DNA were extracted from peripheral whole blood samples using the phenol–chloroform method, and mtDNA CN was assayed by fluorescence-based qPCR. Multivariate unconditional logistic regression models were used to estimate ORs and 95% confidence intervals for the association of mtDNA CN and lung cancer risk.

Results: Overall, mtDNA CN was not associated with lung cancer risk in the PLCO, SWHS, or pooled populations (all P trends > 0.42, P heterogeneity = 0.0001), and mtDNA CN was inversely associated with lung cancer risk among male smokers in PLCO, the opposite direction observed in ATBC. In addition, the mtDNA CN association observed among male heavy smokers in ATBC was the opposite direction in PLCO.

Conclusions: mtDNA CN was not consistently associated with lung cancer risk across three prospective study populations from Europe, Asia, and the United States.

Impact: This pooled study suggests no consistent association between prediagnostic mtDNA CN levels and lung cancer risk across several populations. Cancer Epidemiol Biomarkers Prev; 23(12); 2977–80. ©2014 AACR.