Background: Modern genomic and proteomic studies reveal that many diseases are heterogeneous, comprising multiple different subtypes. The common notion that one biomarker can be predictive for all patients may need to be replaced by an understanding that each subtype has its own set of unique biomarkers, affecting how discovery studies are designed and analyzed.

Methods: We used Monte Carlo simulation to measure and compare the performance of eight selection methods with homogeneous and heterogeneous diseases using both single-stage and two-stage designs. We also applied the selection methods in an actual proteomic biomarker screening study of heterogeneous breast cancer cases.

Results: Different selection methods were optimal, and more than two-fold larger sample sizes were needed for heterogeneous diseases compared with homogeneous diseases. We also found that for larger studies, two-stage designs can achieve nearly the same statistical power as single-stage designs at significantly reduced cost.

Conclusions: We found that disease heterogeneity profoundly affected biomarker performance. We report sample size requirements and provide guidance on the design and analysis of biomarker discovery studies for both homogeneous and heterogeneous diseases.

Impact: We have shown that studies to identify biomarkers for the early detection of heterogeneous disease require different statistical selection methods and larger sample sizes than if the disease were homogeneous. These findings provide a methodologic platform for biomarker discovery of heterogeneous diseases. Cancer Epidemiol Biomarkers Prev; 22(5); 747–55. ©2013 AACR.

Background: It is well accepted that exercise can decrease breast cancer risk. Limited clinical evidence suggests that this risk could be mediated through changes in estrogen metabolism in premenopausal women. Our objective was to investigate the effects of exercise on premenopausal estrogen metabolism pertinent to breast cancer risk.

Methods: Sedentary, healthy, young eumenorrheic women were randomized into an intervention of 30 minutes of moderate-to-vigorous aerobic exercise five times a week for approximately 16 weeks (n = 212), or into a usual-lifestyle sedentary control group (n = 179). Urinary levels of estrogens [estrone [E₁], estradiol, and estriol] and nine estrogen metabolites were measured at baseline and at study end by liquid chromatography/tandem mass spectrometry. The ratios of 2-hydroxyestrone to 16α-hydroxyestrone (2-OHE₁/16α-OHE₁) and 2-OHE₁ to 4-hydroxyestrone (2- OHE₁/4-OHE₁) were also calculated.

Results: The exercise intervention resulted in significant increases in aerobic fitness and lean body mass and a significant decrease in percent body fat. For exercisers who completed the study (n = 165), 2-OHE₁/16α-OHE₁ increased significantly (P = 0.043), whereas E₁ decreased significantly (P = 0.030) in control participants (n = 153). The change from baseline in 2-OHE₁/16α-OHE₁ was significantly different between groups (P = 0.045), even after adjustment for baseline values.

Conclusions: The exercise intervention resulted in a significant increase in the 2-OHE₁/16α-OHE₁ ratio but no differences in other estrogen metabolites or ratios.

Impact: Our results suggest that changes in premenopausal estrogen metabolism may be a mechanism by which increased physical activity lowers breast cancer risk. Cancer Epidemiol Biomarkers Prev; 22(5); 756–64. ©2013 AACR.

Background: Smoking tobacco preparations in a water pipe (hookah) is widespread in many places of the world and is perceived by many as relatively safe. We investigated biomarkers of toxicant exposure with water pipe compared with cigarette smoking.

Methods: We conducted a crossover study to assess daily nicotine and carcinogen exposure with water pipe and cigarette smoking in 13 people who were experienced in using both products.

Results: When smoking an average of 3 water pipe sessions compared with smoking 11 cigarettes per day (cpd), water pipe use was associated with a significantly lower intake of nicotine, greater exposure to carbon monoxide (CO), and a different pattern of carcinogen exposure compared with cigarette smoking, with greater exposure to benzene, and high molecular weight polycyclic aromatic hydrocarbon (PAH), but less exposure to tobacco-specific nitrosamines, 1,3-butadiene, acrolein, acrylonitrile, propylene oxide, ethylene oxide, and low molecular weight PAHs.

Conclusions: A different pattern of carcinogen exposure might result in a different cancer risk profile between cigarette and water pipe smoking. Of particular concern is the risk of leukemia related to high levels of benzene exposure with water pipe use.

Impact: Smoking tobacco in water pipes has gained popularity in the United States and around the world. Many believe that water pipe smoking is not addictive and less harmful than cigarette smoking. We provide data on toxicant exposure that will help guide regulation and public education regarding water pipe health risk. Cancer Epidemiol Biomarkers Prev; 22(5); 765–72. ©2013 AACR.

Background: Physical activity is associated with reductions in fatigue in breast cancer survivors. However, mechanisms underlying this relationship are not well-understood. The purpose of this study was to longitudinally test a model examining the role of self-efficacy and depression as potential mediators of the relationship between physical activity and fatigue in a sample of breast cancer survivors using both self-report and objective measures of physical activity.

Methods: All participants (N = 1,527) completed self-report measures of physical activity, self-efficacy, depression, and fatigue at baseline and 6 months. A subsample was randomly selected to wear an accelerometer at both time points. It was hypothesized that physical activity indirectly influences fatigue via self-efficacy and depression. Relationships among model constructs were examined over the 6-month period using panel analysis within a covariance modeling framework.

Results: The hypothesized model provided a good model-data fit (² = 599.66, df = 105, P ≤ 0.001; CFI = 0.96; SRMR = 0.02) in the full sample when controlling for covariates. At baseline, physical activity indirectly influenced fatigue via self-efficacy and depression. These relationships were also supported across time. In addition, the majority of the hypothesized relationships were supported in the subsample with accelerometer data (² = 387.48, df = 147, P ≤ 0.001, CFI = 0.94, SRMR = 0.04).

Conclusions: This study provides evidence to suggest the relationship between physical activity and fatigue in breast cancer survivors may be mediated by more proximal, modifiable outcomes of physical activity participation.

Impact: Recommendations are made relative to future applications and research concerning these relationships. Cancer Epidemiol Biomarkers Prev; 22(5); 773–81. ©2013 AACR.

Background: Hepatitis B-linked liver cancer disproportionately affects Hmong Americans. With an incidence rate of 18.9 per 100,000, Hmong Americans experience liver cancer at a rate that is 6 to 7 times more than that of non-Hispanic Whites. Serologic testing for the hepatitis B virus (HBV) is a principal means to prevent liver cancer-related deaths through earlier identification of those at risk.

Methods: Academic researchers and Hmong leaders collaborated in the design, conduct, and evaluation of a 5-year randomized controlled trial testing a lay health worker (LHW) intervention to promote HBV testing among 260 Hmong adults through in-home education and patient navigation.

Results: Intervention group participants were more likely to report receiving serologic testing for HBV (24% vs. 10%, P = 0.0056) and showed a greater mean increase in knowledge score (1.3 vs. 0.3 points, P = 0.0003) than control group participants. Multivariable modeling indicated that self-reported test receipt was associated with intervention group assignment [OR 3.5; 95% confidence interval (CI) 1.3–9.2], improvement in knowledge score (OR 1.3 per point; 95% CI 1.02–1.7), female gender (OR 5.3; 95% CI 1.7–16.6), and having seen a doctor in the past year at baseline (OR 4.8; 95% CI 1.3–17.6). The most often cited reason for testing was a doctor's recommendation.

Conclusions: LHWs were effective in bringing about HBV screening. Doctor visits and adherence to doctors' recommendations were pivotal. Participation of health care providers is essential to increase HBV testing.

Impact: LHWs can significantly increase HBV screening rates for Hmong but their doctors' recommendation is highly influential and should be pursued. Cancer Epidemiol Biomarkers Prev; 22(5); 782–91. ©2013 AACR.

Background: The 2007 World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) guidelines encourage cancer survivors to follow its cancer prevention recommendations. We evaluated whether adherence to the WCRF/AICR guidelines for cancer prevention was associated with lower mortality among older female cancer survivors.

Methods: From 2004 to 2009, 2,017 participants in the Iowa Women's Health Study who had a confirmed cancer diagnosis (1986–2002) and completed the 2004 follow-up questionnaire were followed. Adherence scores for the WCRF/AICR guidelines for body weight, physical activity, and diet were computed assigning one, 0.5 or 0 points to each of eight recommendations depending on the degree of adherence. All-cause (n = 461), cancer-specific (n = 184), and cardiovascular disease (CVD)-specific mortality (n = 145) were compared by the total adherence score and by adherence scores for each of the three components of the recommendations.

Results: Women with the highest (6–8) versus lowest (0–4) adherence score had lower all-cause mortality [HR = 0.67; 95% confidence of interval (CI), 0.50–0.94]. Meeting the physical activity recommendation was associated with lower all-cause (P_trend < 0.0001), cancer-specific (P_trend = 0.04), and CVD-specific mortality (P_trend = 0.03). Adherence to dietary recommendations was associated with lower all-cause mortality (P_trend < 0.05), whereas adherence to the body weight recommendation was associated with higher all-cause mortality (P_trend = 0.009).

Conclusions: Adherence to the WCRF/AICR guidelines was associated with lower all-cause mortality among older female cancer survivors. Adherence to the physical activity recommendation had the strongest association with lower all-cause and disease-specific mortality.

Impact: Older cancer survivors may decrease their risk of death by leading a healthy lifestyle after a cancer diagnosis. Cancer Epidemiol Biomarkers Prev; 22(5); 792–802. ©2013 AACR.

Background: Increased risk of pancreatic cancer has been reported in breast cancer families carrying BRCA1and BRCA2 mutations; however, pancreatic cancer risk in mutation-negative (BRCAX) families has not been explored to date. The aim of this study was to estimate pancreatic cancer risk in high-risk breast cancer families according to the BRCA mutation status.

Methods: A retrospective cohort analysis was applied to estimate standardized incidence ratios (SIR) for pancreatic cancer. A total of 5,799 families with ≥1 breast cancer case tested for mutations in BRCA1 and/or BRCA2 were eligible. Families were divided into four classes: BRCA1, BRCA2, BRCAX with ≥2 breast cancer diagnosed before age 50 (class 3), and the remaining BRCAX families (class 4).

Results: BRCA1 mutation carriers were at increased risk of pancreatic cancer [SIR = 4.11; 95% confidence interval (CI), 2.94–5.76] as were BRCA2 mutation carriers (SIR = 5.79; 95% CI, 4.28–7.84). BRCAX family members were also at increased pancreatic cancer risk, which did not appear to vary by number of members with early-onset breast cancer (SIR = 1.31; 95% CI, 1.06–1.63 for class 3 and SIR = 1.30; 95% CI, 1.13–1.49 for class 4).

Conclusions: Germline mutations in BRCA1 and BRCA2 are associated with an increased risk of pancreatic cancer. Members of BRCAX families are also at increased risk of pancreatic cancer, pointing to the existence of other genetic factors that increase the risk of both pancreatic cancer and breast cancer.

Impact: This study clarifies the relationship between familial breast cancer and pancreatic cancer. Given its high mortality, pancreatic cancer should be included in risk assessment in familial breast cancer counseling. Cancer Epidemiol Biomarkers Prev; 22(5); 803–11. ©2013 AACR.

Background: Aristolochic acid is a toxin found in plants of the genus Aristolochia, to which humans can be exposed either through certain Chinese herbal medicines or through inadvertent commingling with food crops. Our objective was to estimate cumulative exposures of aristolochic acid associated with increased risk of end-stage renal disease (ESRD), and to conduct a systematic review and meta-analysis on aristolochic acid-induced upper tract urothelial carcinoma (UUC).

Methods: Using epidemiologic studies on aristolochic acid-related disease from multiple different regions of the world, a systematic review was conducted in which relative risks (RR), HRs, and ORs were derived or extracted directly, and a meta-analysis was conducted. One study was used to estimate a benchmark dose lower confidence limit (BMDL) for aristolochic acid-related ESRD.

Results: Mean values for risk ratios, ORs, RRs, or HRs, of UUC caused by aristolochic acid ranged from 1 to 49. A meta-analysis of these studies resulted in a pooled OR of 5.97 [95% confidence interval (CI), 2.78–12.84] for this aristolochic acid-related cancer. The obtained BMDL for aristolochic acid-related ESRD was 0.42 g cumulative aristolochic acid exposure.

Conclusions: Aristolochic acid exposure is significantly associated with an increased risk of UUC, and there is a dose-dependent relationship between cumulative aristolochic acid exposure and ESRD risk.

Impact: Individuals who use certain Chinese herbal medicines may significantly increase their risk of developing UUC and/or ESRD, as would individuals who are inadvertently exposed to aristolochic acid through commingling of Aristolochia plants with harvested food crops. Cancer Epidemiol Biomarkers Prev; 22(5); 812–20. ©2013 AACR.

Background: Striking similarities between autoimmune gastritis and Helicobacter Pylori (H. pylori)-associated gastritis have suggested a potential link between these two pathologic conditions in the progression of chronic atrophic gastritis (CAG); however, evidence has remained conflicting.

Methods: Serum pepsinogen I and II, and antibodies against H. pylori in general, the cytotoxin-associated gene A protein (CagA) and parietal cells were measured by ELISA in 9,684 subjects aged 50 to 74 years. Antigastric parietal cell antibody (APCA) prevalence was examined in the overall population and according to sex, age, and H. pylori serostatus. The association between APCA prevalence and CAG was assessed by logistic regression, overall and according to H. pylori status, controlling for potential confounding factors.

Results: Overall APCA prevalence was 19.5%. APCA prevalence was strongly associated with CAG, and the association was increasing with increasing severity of CAG. Furthermore, the association between APCA and CAG was even stronger among H. pylori-negative subjects [odds ratio (OR) = 11.3; 95% confidence interval (CI): 7.5–17.1)] than among H. pylori-positive subjects (OR = 2.6; 95% CI: 2.1–3.3).

Conclusions: APCA may play a role on the development of gastric atrophy, irrespective of H. pylori infection.

Impact: Assessment of APCA might be a useful complement to established markers (such as pepsinogens and H. pylori antibodies) in screening for CAG. Cancer Epidemiol Biomarkers Prev; 22(5); 821–6. ©2013 AACR.

Background: Angiogenesis and lymphangiogenesis are important in the progression of melanoma. We investigated associations between genetic variants in these pathways with sentinel lymph node (SLN) metastasis and mortality in 2 independent series of patients with melanoma.

Methods: Participants at Moffitt Cancer Center were 552 patients, all Caucasian, with primary cutaneous melanoma referred for SLN biopsy. A total of 177 patients had SLN metastasis, among whom 60 died from melanoma. Associations between 238 single-nucleotide polymorphisms (SNP) in 26 genes and SLN metastasis were estimated as ORs and 95% confidence intervals (CI) using logistic regression. Competing risk regression was used to estimate HRs and 95% CI for each SNP and melanoma-specific mortality. We attempted to replicate significant findings using data from a genome-wide association study comprising 1,115 patients with melanoma who were referred for SLN biopsy from MD Anderson Cancer Center (MDACC), among whom 189 patients had SLN metastasis and 92 patients died from melanoma.

Results: In the Moffitt dataset, we observed significant associations in 18 SNPs with SLN metastasis and 17 SNPs with mortality. Multiple SNPs in COL18A1, EGF receptor (EGFR), FLT1, interleukin (IL)-10, platelet-derived growth factor D (PDGFD), PIK3CA, and toll-like receptor (TLR)-3 were associated with the risk of SLN metastasis and/or patient mortality. The MDACC data set replicated an association between mortality and rs2220377 in PDGFD. Furthermore, in a meta-analysis, 3 additional SNPs were significantly associated with SLN metastasis (EGFR rs723526 and TLR3 rs3775292) and melanoma-specific death (TLR3 rs7668666).

Conclusions: These findings suggest that genetic variation in angiogenesis and lymphangiogenesis contributes to regional nodal metastasis and progression of melanoma.

Impact: Additional research attempting to replicate these results is warranted. Cancer Epidemiol Biomarkers Prev; 22(5); 827–34. ©2013 AACR.

Background: Women who were younger at their first live birth have a reduced breast cancer risk. Other pregnancy characteristics, including complications, also may affect risk but because they are rare, require large datasets to study.

Methods: The association of pregnancy history and breast cancer risk was assessed in a population-based study including 22,646 cases diagnosed in Washington State 1974 to 2009, and 224,721 controls, frequency matched on parity, age, calendar year of delivery, and race/ethnicity. Information on prediagnosis pregnancies derived from linked birth certificate and hospital discharge databases. Adjusted odd ratios (ORs) and 95% confidence intervals (CI) were calculated.

Results: Multiple gestation pregnancies were associated with decreased breast cancer risk (OR, 0.65; 95% CI, 0.57–0.74) as was prepregnancy obesity (OR, 0.76; 95% CI, 0.65–0.90). Infant birth weight was positively associated (6% per 1,000 g; 95% CI, 3%–9%). The ORs for first trimester bleeding (OR, 3.35; 95% CI, 1.48–7.55) and placental abnormality/insufficiency (OR, 2.24; 95% CI, 1.08–4.67) were increased in women diagnosed at age 50+ years and 15+ years after the index pregnancy. Results were similar in analyses restricted to first pregnancies, those closest to diagnosis, and when excluding in situ disease.

Conclusion: These data suggest that multiple gestation pregnancies are protective, whereas delivering larger infants increases risk for later development of maternal breast cancer. Placental abnormalities that result in bleeding in pregnancy also may reverse the long-term protection in postmenopausal women associated with parity.

Impact: Certain pregnancy characteristics seem to be associated with later maternal breast cancer risk. Cancer Epidemiol Biomarkers Prev; 22(5); 835–47. ©2013 AACR.

Background: Aside from exposure to ionizing radiation and benzene, little is known about lifestyle risk factors for chronic myeloid leukemia (CML) in the general population.

Methods: We examined the relation between lifestyle and dietary risk factors for CML in 493,188 participants (294,271 males and 198,917 females) aged 50 to 71 years who completed a baseline questionnaire in the National Institutes of Health-AARP Diet and Health Study in 1995 to 1996. Over a median of 10.5 years of follow-up, 178 incident cases of CML (139 males and 39 females) were ascertained from state registries. We used Cox proportional hazards models to estimate hazard ratios and 95% confidence intervals for exposures of interest, adjusting for potential confounding variables.

Results: In multivariable analysis of all participants combined, female sex, years of education, and vigorous physical activity (HR for ≥3 times/week vs. <1 time/week 0.70; 95% CI, 0.49–0.99) were inversely associated with risk of CML, whereas smoking intensity (HR for smokers of ≥20 cigarettes per day vs. never smokers: 1.53; 95% CI, 1.03–2.27) and body mass (HR for BMI ≥ 30 vs. <25 kg/m² 1.46; 95% CI, 0.95–2.23) were associated with increased risk. A range of dietary factors was not associated with disease.

Conclusions: This study adds to the sparse information about lifestyle factors, which affect the risk of CML in the general population.

Impact: If these findings are confirmed, it would suggest that CML may be amenable to preventive strategies. Cancer Epidemiol Biomarkers Prev; 22(5); 848–54. ©2013 AACR.

Chronic inflammation may play a role in the development of pancreatic cancer. However, few prospective studies have examined the association between plasma inflammatory markers and pancreatic cancer risk. Therefore, we investigated the association of prediagnostic circulating C-reactive protein (CRP), interleukin-6 (IL-6), and TNF-α receptor II (TNF-αR2) with subsequent pancreatic cancer risk in a prospective, nested case–control study of 470 cases and 1,094 controls from Health Professionals Follow-up Study, Nurses' Health Study, Physicians' Health Study, Women's Health Initiative, and Women's Health Study. The median follow-up time of cases was 7.2 years (range 1–26 years). No association was observed between plasma CRP, IL-6, and TNF-αR2 and the risk of pancreatic cancer. Comparing extreme quintiles, the multivariate ORs were 1.10 [95% confidence interval (CI), 0.74–1.63; P_trend = 0.81] for CRP, 1.19 (95% CI, 0.81–1.76; P_trend = 0.08) for IL-6, and 0.88 (95% CI, 0.58–1.33; P_trend = 0.57) for TNF-αR2. In conclusion, prediagnostic levels of circulating CRP, IL-6, and TNF-αR2 were not associated with the risk of pancreatic cancer, suggesting that systemic inflammation as measured by circulating inflammatory factors is unlikely to play a major role in the development of pancreatic cancer. Cancer Epidemiol Biomarkers Prev; 22(5); 855–61. ©2013 AACR.

Background: Smoking is a recently established risk factor for colon cancer. We wanted to explore the hypothesis that women may be more susceptible to smoking-attributed colon cancer than men as one of the possible explanations for the high colon cancer risk of Norwegian women.

Methods: We followed 602,242 participants aged 19 to 67 years at enrollment in 1972–2003, by linkage to national registries through December 2007. We used Cox proportional hazard models to estimate HRs and 95% confidence intervals (CI).

Results: During a mean follow-up of 14 years, altogether 3,998 (46% women) subjects developed colon cancer. Female ever-smokers had a 19% (HR = 1.19, 95% CI = 1.09–1.32) and male ever-smokers an 8% (HR = 1.08, CI = 0.97–1.19) increased risk of colon cancer compared with never smokers. For all the four dose–response variables examined, female ever-smokers in the most exposed category of smoking initiation, (HR = 1.48, 95% CI = 1.21–1.81), of daily cigarette consumption (HR = 1.28, 95% CI = 1.06–1.55), of smoking duration (HR = 1.47, 95% CI = 1.11–1.95), and of pack-years of smoking (HR = 1.33, 95% CI = 1.11–1.57) had a significantly increased risk of more than 20% for colon cancer overall and of more than 40% for proximal colon cancer, compared with never smokers. A test for heterogeneity by gender was statistically significant only for ever smoking and risk of proximal colon cancer (Wald ², P = 0.02).

Conclusions: Female smokers may be more susceptible to colon cancer and especially to proximal colon cancer than male smokers.

Impact: Women who smoke are more vulnerable to colon cancer than men. Cancer Epidemiol Biomarkers Prev; 22(5); 862–71. ©2013 AACR.

Background: Although positive associations have consistently been reported between sleep disruption and breast cancer, less is known about its potential role in prostate cancer.

Methods: Within the prospective AGES-Reykjavik cohort study, we followed 2,102 men recruited in 2002–2006 until the end of 2009. Participants answered questions on sleep disruption. Information on the occurrence of prostate cancer was obtained through record linkages across the Icelandic Cancer Registry. We used Cox regression models with 95% confidence intervals (CI) to estimate HRs of prostate cancer by symptoms of sleep disruption.

Results: During follow-up, 135 men (6.4%) were diagnosed with prostate cancer. Compared with men without sleep disruption, those with problems falling and staying asleep were at significantly increased risk of prostate cancer [HR, 1.7 (95% CI, 1.0–2.9) and 2.1 (95% CI, 1.2–3.7)], respectively, with increasing sleep disruption severity. When restricted to advanced prostate cancer (≥ stage T3 or lethal disease), these associations became even stronger [HR 2.1 (95% CI, 0.7–6.2) and 3.2 (95% CI, 1.1–9.7)]. The results did not change after excluding from the analyses men who woke up during the night, indicative of nocturia, suggesting limited risk of reverse association.

Conclusions: Our data suggest that certain aspects of sleep disruption may confer an increased risk of prostate cancer and call for additional, larger studies with longer follow-up times.

Impact: Prostate cancer is one of the leading public health concerns in men; if confirmed in future studies, the association between sleep disruption and prostate cancer risk may open new avenues for prevention. Cancer Epidemiol Biomarkers Prev; 22(5); 872–9. ©2013 AACR.

Background: There are several well-established environmental risk factors for ovarian cancer, and recent genome-wide association studies have also identified six variants that influence disease risk. However, the interplay between such risk factors and susceptibility loci has not been studied.

Methods: Data from 14 ovarian cancer case–control studies were pooled, and stratified analyses by each environmental risk factor with tests for heterogeneity were conducted to determine the presence of interactions for all histologic subtypes. A genetic "risk score" was created to consider the effects of all six variants simultaneously. A multivariate model was fit to examine the association between all environmental risk factors and genetic risk score on ovarian cancer risk.

Results: Among 7,374 controls and 5,566 cases, there was no statistical evidence of interaction between the six SNPs or genetic risk score and the environmental risk factors on ovarian cancer risk. In a main effects model, women in the highest genetic risk score quartile had a 65% increased risk of ovarian cancer compared with women in the lowest [95% confidence interval (CI), 1.48–1.84]. Analyses by histologic subtype yielded risk differences across subtype for endometriosis (P_het < 0.001), parity (P_het < 0.01), and tubal ligation (P_het = 0.041).

Conclusions: The lack of interactions suggests that a multiplicative model is the best fit for these data. Under such a model, we provide a robust estimate of the effect of each risk factor that sets the stage for absolute risk prediction modeling that considers both environmental and genetic risk factors. Further research into the observed differences in risk across histologic subtype is warranted. Cancer Epidemiol Biomarkers Prev; 22(5); 880–90. ©2013 AACR.

Background: Despite more aggressive screening across all demographics and gradual declines in mortality related to prostate cancer (PCa) in the United States, disparities among populations persist. A substantial proportion of African American men (AAM) have a higher overall incidence, earlier age of onset, increased proportion of clinically advanced disease, and increased bone metastases and mortality from PCa compared to European American men (EAM). Limited early evidence indicates that underlying causes for disparities may be observed in tumor-specific gene expression programs.

Methods: This study used microarray-based methods to measure expression levels for 517 genes that were previously associated with PCa in archived formalin-fixed paraffin embedded (FFPE) specimens; testing the hypothesis that gene expression features of functional consequence to cancer distinguish PCa from AAM and EAM. A t test was conducted comparing AAM to EAM expression levels for each probe on the array.

Results: Analysis of 639 tumor samples (270 AAM, 369 EAM) showed that 95 genes were overexpressed specifically in PCa from AAM relative to EAM and 132 were overexpressed in PCa from EAM relative to AAM. Furthermore, systems-level analyses highlight the relevant signaling pathways and functions associated with the EAM- or AAM-specific overexpressed gene sets, for example, inflammation and lipid metabolism.

Conclusions: Results here bring further understanding to the potential for molecular differences for PCa in AAM versus EAM.

Impact: The results support the notion that therapeutic benefits will be realized when targeted treatments are designed to acknowledge and address a greater spectrum of PCa subtypes and molecular distinctions. Cancer Epidemiol Biomarkers Prev; 22(5); 891–7. ©2013 AACR.

Background: In general population studies, obesity has been associated with risk of high-grade prostate cancer, but little is known about obesity and future prostate cancer risk among men with an initial benign biopsy of the prostate; a high-risk population.

Methods: Within a cohort of 6,692 men followed up after a biopsy or transurethral resection of the prostate (TURP) with benign findings, a nested case–control study was conducted of 494 prostate cancer cases and controls matched on age, race, follow-up duration, biopsy versus TURP and date of procedure. Body mass index at the time of the initial procedure was abstracted from medical records, and initial biopsy specimens were reviewed for the presence of prostatic intraepithelial neoplasia (PIN).

Results: Obesity was associated with the presence of PIN in the initial benign specimen [OR = 2.15; 95% confidence interval (CI) 1.13–4.11]. After adjustment for the matching variables, family history of prostate cancer, prostate-specific antigen (PSA) levels at the initial procedure, the number of PSA tests and digital rectal examinations during follow-up, obesity (OR = 1.57; 95% CI, 1.07–2.30) at the time of the initial procedure was associated with prostate cancer incidence during follow-up. Risk associated with obesity was confined to cases with follow-up less than 1,538 days, the median duration of follow-up among cases (OR = 1.95; 95% CI, 1.09–3.48).

Conclusions: Obesity is associated with the presence of PIN in benign specimens and with future prostate cancer risk after an initial benign finding.

Impact: Obesity may be a factor to consider when planning clinical follow-up after a benign biopsy. Cancer Epidemiol Biomarkers Prev; 22(5); 898–904. ©2013 AACR.

Background: Several observational studies assessed the relationship between serum 25-hydroxyvitamin D [25(OH)D] concentrations and the risk of cancer but results were inconclusive.

Methods: We measured 25(OH)D concentrations in a population-based cohort study of 9,949 men and women ages 50 to 74 years in Saarland, Germany. Comprehensively adjusted Cox regression models were applied to estimate HRs and 95% confidence intervals (CI) for the association between season-standardized 25(OH)D concentrations and total and site-specific cancer incidence.

Results: Overall, during a median of 8 years of follow-up, 873 subjects developed cancer; the most common being prostate (171), breast (137), lung (136), and colorectal (136) cancer. Low season-standardized 25(OH)D (<30, 35, 40, or 36 nmol/L in winter, spring, summer, and autumn, respectively) was neither significantly associated with total cancer incidence (HR, 1.10; 95% CI, 0.93–1.30) nor with site-specific cancer incidence. However, a significantly increased overall cancer risk was observed for low 25(OH)D among men, nonobese subjects and subjects reporting low fish consumption and for high 25(OH)D in nonsmokers and nonobese subjects. Accordingly, restricted cubic splines to investigate dose–response relationships curves showed an inverse association of 25(OH)D levels and total cancer risk in men but not in women.

Conclusions: 25(OH)D concentrations were significantly associated with overall cancer incidence in subgroups of this large cohort from Germany. No significant association was observed with site-specific cancers but this could be due to a limited statistical power for these endpoints.

Impact: Further research should clarify whether and to what extent specific risk groups might profit from vitamin D supplementation. Cancer Epidemiol Biomarkers Prev; 22(5); 905–16. ©2013 AACR.

Background: Previous reports suggest that relatives of colorectal cancer (CRC)-affected probands carrying the BRAF p.V600E mutation are at an increased risk of CRC and extracolonic cancers (ECC). In this study, we estimated the association between a family history of either CRC or ECC and risk of CRC with a BRAF p.V600E mutation.

Methods: Population-based CRC cases (probands, ages 18–59 years at diagnosis), recruited irrespective of family cancer history, were characterized for BRAF p.V600E mutation and mismatch repair (MMR) status. ORs and 95% confidence intervals (CI) were estimated using multivariable logistic regression.

Results: The 690 eligible probands showed a mean age at CRC diagnosis of 46.9 ± 7.8 years, with 313 (47.9%) reporting a family history of CRC and 53 (7.7%) that were BRAF-mutated. Probands with BRAF-mutated, MMR-proficient CRCs were less likely to have a family history of CRC than probands that were BRAF wild-type (OR, 0.46; 95% CI, 0.24–0.91; P = 0.03). For probands with a BRAF-mutated CRC, the mean age at diagnosis was greater for those with a CRC-affected first- or second-degree relative (49.3 ± 6.4 years) compared with those without a family history (43.8 ± 10.2 years; P = 0.04). The older the age at diagnosis of CRC with the BRAF p.V600E mutation, the more likely these probands were to show a family history of CRC (OR, 1.09 per year of age; 95% CI, 1.00–1.18; P = 0.04).

Conclusions: Probands with early-onset, BRAF-mutated, and MMR-proficient CRC were less likely to have a family history of CRC than probands that were BRAF-wild-type.

Impact: These findings provide useful insights for cancer risk assessment in families and suggest that familial or inherited factors are more important in early-onset, BRAF-wild-type CRC. Cancer Epidemiol Biomarkers Prev; 22(5); 917–26. ©2013 AACR.

Background: Dietary and circulating carotenoids have been inversely associated with breast cancer risk, but observed associations may be due to confounding. Single-nucleotide polymorphisms (SNPs) in β-carotene 15,15'-monooxygenase 1 (BCMO1), a gene encoding the enzyme involved in the first step of synthesizing vitamin A from dietary carotenoids, have been associated with circulating carotenoid concentrations and may serve as unconfounded surrogates for those biomarkers. We determined associations between variants in BCMO1 and breast cancer risk in a large cohort consortium.

Methods: We used unconditional logistic regression to test four SNPs in BCMO1 for associations with breast cancer risk in 9,226 cases and 10,420 controls from the National Cancer Institute Breast and Prostate Cancer Cohort Consortium (BPC3). We also tested weighted multi-SNP scores composed of the two SNPs with strong, confirmed associations with circulating carotenoid concentrations.

Results: Neither the individual SNPs nor the weighted multi-SNP scores were associated with breast cancer risk [OR (95% confidence interval) comparing extreme quintiles of weighted multi-SNP scores = 1.04 (0.94–1.16) for β-carotene, 1.08 (0.98–1.20) for α-carotene, 1.04 (0.94–1.16) for β-cryptoxanthin, 0.95 (0.87–1.05) for lutein/zeaxanthin, and 0.92 (0.83–1.02) for retinol]. Furthermore, no associations were observed when stratifying by estrogen receptor status, but power was limited.

Conclusions: Our results do not support an association between SNPs associated with circulating carotenoid concentrations and breast cancer risk.

Impact: Future studies will need additional genetic surrogates and/or sample sizes at least three times larger to contribute evidence of a causal link between carotenoids and breast cancer. Cancer Epidemiol Biomarkers Prev; 22(5); 927–36. ©2013 AACR.

Background: 4-Aminobiphenyl (ABP) is an established human bladder carcinogen, with tobacco smoke being a major source of human exposure. Other arylamine compounds, including 2,6-dimethylaniline (2,6-DMA), have been implicated as possible human bladder carcinogens. Hemoglobin adducts of 4-ABP and 2,6-DMA are validated biomarkers of exposure to those compounds in humans.

Methods: The Shanghai Bladder Cancer Study enrolled 581 incident bladder cancer cases and 604 population controls. Each participant was solicited for his/her history of tobacco use and other lifestyle factors and donation of blood and urine specimens. Red blood cell lysates were used to quantify both hemoglobin adducts of 4-ABP and 2,6-DMA. Urine samples were used to quantify total cotinine. ORs and 95% confidence intervals (CI) for bladder cancer were estimated using unconditional logistic regression methods.

Results: Among lifelong nonsmokers, ORs (95% CIs) of bladder cancer for low (below median of positive values) and high versus undetectable levels of 2,6-DMA hemoglobin adducts were 3.87 (1.39–10.75) and 6.90 (3.17–15.02), respectively (P_trend < 0.001). Similarly, among lifelong nonsmokers, ORs (95% CIs) of bladder cancer for third and fourth versus first/second quartiles of 4-ABP hemoglobin adducts was 1.30 (0.76–2.22) and 2.29 (1.23–4.24), respectively (P_trend = 0.009). The two associations were independent of each other.

Conclusion: Hemoglobin adducts of 4-ABP and 2,6-DMA were significantly and independently associated with increased bladder cancer risk among lifelong nonsmokers in Shanghai, China.

Impact: The findings of the present study in China with previous data in Los Angeles, California strongly implicate arylamines as potential causal agents of human bladder cancer. Cancer Epidemiol Biomarkers Prev; 22(5); 937–45. ©2013 AACR.

Background: Women with a personal history of breast cancer (PHBC) have increased risk of an interval cancer. We aimed to identify risk factors for second (ipsilateral or contralateral) screen-detected or interval breast cancer within 1 year of screening in PHBC women.

Methods: Screening mammograms from women with history of early-stage breast cancer at Breast Cancer Surveillance Consortium-affiliated facilities (1996–2008) were examined. Associations between woman-level, screen-level, and first cancer variables and the probability of a second breast cancer were modeled using multinomial logistic regression for three outcomes [screen-detected invasive breast cancer, interval invasive breast cancer, or ductal carcinoma in situ (DCIS)] relative to no second breast cancer.

Results: There were 697 second breast cancers, of these 240 were interval cancers, among 67,819 screens in 20,941 women. In separate models for women with DCIS or invasive first cancer, first breast cancer surgery predicted all three second breast cancer outcomes (P < 0.001), and high ORs for second breast cancers (between 1.95 and 4.82) were estimated for breast conservation without radiation (relative to mastectomy). In women with invasive first breast cancer, additional variables predicted risk (P < 0.05) for at least one of the three outcomes: first-degree family history, dense breasts, longer time between mammograms, young age at first breast cancer, first breast cancer stage, and adjuvant systemic therapy for first breast cancer; and risk of interval invasive breast cancer was highest in women <40 years at first breast cancer (OR, 3.41; 1.34–8.70), those with extremely dense breasts (OR, 2.55; 1.4–4.67), and those treated with breast conservation without radiation (OR, 2.67; 1.53–4.65).

Conclusion: Although the risk of a second breast cancer is modest, our models identify risk factors for interval second breast cancer in PHBC women.

Impact: Our findings may guide discussion and evaluations of tailored breast screening in PHBC women, and incorporating this information into clinical decision-making warrants further research. Cancer Epidemiol Biomarkers Prev; 22(5); 946–61. ©2013 AACR.

Background: The E-Screen bioassay can measure the mitogenicity of human serum and thus may be useful as a biomarker in epidemiologic studies of breast cancer. While the assay's MCF-7 cells are known to proliferate in response to estrogen, the specific determinants of variation in E-Screen activity in human serum samples are poorly understood. We sought to identify serum molecules and patient characteristics associated with serum E-Screen activity among postmenopausal women.

Methods: Postmenopausal women (N = 219) aged 55 to 70 years with no history of postmenopausal hormone use or breast cancer completed a questionnaire and provided a blood sample. Serum was analyzed for E-Screen activity and a variety of molecules including sex hormones, growth factors, and environmental chemicals. Stepwise selection procedures were used to identify correlates of E-Screen activity.

Results: Serum samples from all women had detectable E-Screen activity, with a median estradiol equivalents value of 0.027 ng/mL and interquartile range of 0.018–0.036 ng/mL. In the final multivariable-adjusted model, serum E-Screen activity was positively associated with serum estradiol, estrone, insulin-like growth factor–binding protein (IGFBP)-3, and testosterone levels (all P < 0.05), as well as body mass index (P = 0.03). Serum E-Screen activity was lower among women with higher SHBG (P < 0.0001) and progesterone levels (P = 0.03).

Conclusion: Serum E-Screen activity varies according to levels of endogenous estrogens and other serum molecules. Obesity appears to confer additional serum mitogenicity beyond its impact on the measured hormones and growth factors.

Impact: By capturing mitogenicity due to a variety of patient and serum factors, the E-Screen may provide advantages for use as a biomarker in breast cancer studies. Cancer Epidemiol Biomarkers Prev; 22(5); 962–71. ©2013 AACR.

Background: Breast cancer bone metastasis is a complication that significantly compromises patient survival due, in part, to the lack of disease-specific biomarkers that allow early and accurate diagnosis.

Methods: Using mass spectrometry protein profiling, plasma samples were screened from three independent breast cancer patient cohorts with and without clinical evidence of bone metastasis.

Results: The results identified 13 biomarkers that classified all 110 patients with a sensitivity of 91% and specificity of 93% [receiver operating characteristics area under the curve (AUC = 1.00)]. The most discriminatory protein was subsequently identified as a unique 12-48aa peptide fragment of parathyroid hormone-related protein (PTHrP). PTHrP(12-48) was significantly increased in plasma of patients with bone metastasis compared with patients without bone metastasis (P < 0.0001). Logistic regression models were used to evaluate the diagnostic potential of PTHrP(12-48) as a single biomarker or in combination with the measurement of the clinical marker N-telopeptide of type I collagen (NTx). The PTHrP(12-48) and NTx logistic regression models were not significantly different and classified the patient groups with high accuracy (AUC = 0.85 and 0.95), respectively. Interestingly, in combination with serum NTx, the plasma concentration of PTHrP(12-48) increased diagnostic specificity and accuracy (AUC = 0.99).

Conclusions: These data show that PTHrP(12-48) circulates in plasma of patient with breast cancer and is a novel and predictive biomarker of breast cancer bone metastasis. Importantly, the clinical measurement of PTHrP(12-48) in combination with NTx improves the detection of breast cancer bone metastasis.

Impact: In summary, we present the first validated, plasma biomarker signature for diagnosis of breast cancer bone metastasis that may improve the early diagnosis of high-risk individuals. Cancer Epidemiol Biomarkers Prev; 22(5); 972–83. ©2013 AACR.

Background: Female steroid hormone levels and exogenous hormone use influence breast cancer risk. We investigated the association between genetic variation in the hormone metabolism and signaling pathway and mammographic density, a strong predictor of breast cancer risk.

Methods: We genotyped 161 SNPs in 15 hormone metabolism pathway gene regions and evaluated mammographic density in 2,038 Singapore Chinese women. Linear regression analysis was used to investigate single-nucleotide polymorphism (SNP) and mammographic density association. An overall pathway summary was obtained using the adaptive ranked truncated product test.

Results: We did not find any of the individually tested SNPs to be associated with mammographic density after a multiple testing correction. There was no evidence of an overall effect on mammographic density of genetic variation in the hormone metabolism pathway.

Conclusions: In this cross-sectional study, genetic variation in hormone metabolism pathway was not associated with mammographic density in Singapore Chinese women.

Impact: Consistent with existing data from Caucasian populations, polymorphisms in hormone pathway genes are not likely to be strong predictors of mammographic density in Asian women. Cancer Epidemiol Biomarkers Prev; 22(5); 984–6. ©2013 AACR.

Background: Ovarian cancer is a leading cause of cancer-related death among women. In an effort to understand contributors to disease outcome, we evaluated single-nucleotide polymorphisms (SNP) previously associated with ovarian cancer recurrence or survival, specifically in angiogenesis, inflammation, mitosis, and drug disposition genes.

Methods: Twenty-seven SNPs in VHL, HGF, IL18, PRKACB, ABCB1, CYP2C8, ERCC2, and ERCC1 previously associated with ovarian cancer outcome were genotyped in 10,084 invasive cases from 28 studies from the Ovarian Cancer Association Consortium with over 37,000-observed person-years and 4,478 deaths. Cox proportional hazards models were used to examine the association between candidate SNPs and ovarian cancer recurrence or survival with and without adjustment for key covariates.

Results: We observed no association between genotype and ovarian cancer recurrence or survival for any of the SNPs examined.

Conclusions: These results refute prior associations between these SNPs and ovarian cancer outcome and underscore the importance of maximally powered genetic association studies.

Impact: These variants should not be used in prognostic models. Alternate approaches to uncovering inherited prognostic factors, if they exist, are needed. Cancer Epidemiol Biomarkers Prev; 22(5); 987–. ©2013 AACR.

Background: Concerns have been raised about the risk of dementia associated with antiestrogen adjuvant therapy in breast cancer, but study results have been inconsistent. We examined whether tamoxifen or other endocrine therapy was associated with dementia risk in a large population of patients with breast cancer.

Methods: We used Danish nationwide medical registries to identify patients with breast cancer diagnosed between 1990 and 2004, use of endocrine therapy, and subsequent diagnoses of dementia. We used Cox regression to estimate the risk of dementia among patients who received five years of tamoxifen or other endocrine therapies.

Results: The study included 16,419 patients with breast cancer. In this cohort, 37% were unexposed to endocrine therapy, 9% had five years of tamoxifen therapy, and 54% had other endocrine regimens, some of them containing tamoxifen for less than five years with subsequent aromatase inhibitor therapy. Tamoxifen therapy was associated with a near-null risk of dementia [HR, 1.4; 95% confidence interval (CI), 1.0–1.9], and a null association was observed after death was taken into account as a competing risk (sub-HR, 1.0; 95% CI, 0.76–1.4).

Conclusions: No clinically relevant association between use of tamoxifen or other endocrine therapy and risk of dementia was observed.

Impact: Our result contradicts earlier research findings suggesting tamoxifen and other endocrine therapies increase the risk of dementia in breast cancer patients. Cancer Epidemiol Biomarkers Prev; 22(5); 993–6. ©2013 AACR.

Background: It has been hypothesized that genomic instability related to telomere dysfunction may contribute to carcinogenesis. There is some evidence from case–control studies suggesting that short leukocyte telomere length may be associated with an increased risk of renal cell carcinoma (RCC); however, this association has not been investigated prospectively.

Methods: We conducted a nested case–control study (209 cases, 410 controls) of RCC risk in relation to prediagnostic leukocyte telomere length in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. ORs and 95% confidence intervals (CI) were estimated using conditional logistic regression.

Results: Leukocyte telomere length was not significantly associated with future risk of RCC (highest quartile vs. lowest: OR, 0.8; 95% CI, 0.5–1.5; P_trend = 0.6). Analyses stratified by sex, age, and time from blood collection to RCC diagnosis were similarly null.

Conclusions: The results of this study, to our knowledge the first prospective investigation of its kind, do not support an association between prediagnostic leukocyte telomere length and risk of RCC.

Impact: In contrast to some earlier reports, our findings add to the evidence that leukocyte telomere length is not a biomarker of risk related to the etiology of RCC. Cancer Epidemiol Biomarkers Prev; 22(5); 997–1000. ©2013 AACR.