Background: Between- and within-person variation in DNA methylation levels are important parameters to be considered in epigenome-wide association studies. Temporal change is one source of within-person variation in DNA methylation that has been linked to aging and disease.
Methods: We analyzed CpG-site–specific intraindividual variation and short-term temporal trend in leukocyte DNA methylation among 24 healthy Chinese women, with blood samples drawn at study entry and after 9 months. Illumina HumanMethylation450 BeadChip was used to measure methylation. Intraclass correlation coefficients (ICC) and trend estimates were summarized by genomic location and probe type.
Results: The median ICC was 0.36 across nonsex chromosomes and 0.80 on the X chromosome. There was little difference in ICC profiles by genomic region and probe type. Among CpG loci with high variability between participants, more than 99% had ICC > 0.8. Statistically significant trend was observed in 10.9% CpG loci before adjustment for cell-type composition and in 3.4% loci after adjustment.
Conclusions: For CpG loci differentially methylated across subjects, methylation levels can be reliably assessed with one blood sample. More samples per subject are needed for low-variability and unmethylated loci. Temporal changes are largely driven by changes in cell-type composition of blood samples, but temporal trend unrelated to cell types is detected in a small percentage of CpG sites.
Background: Germline mutations in the BRCA1 and BRCA2 genes confer an estimated 58% to 80% lifetime risk of breast cancer. In general, screening is done for cancer patients if a relative has been diagnosed with breast or ovarian cancer. There are few data on the prevalence of mutations in these genes in Mexican women with breast cancer and this hampers efforts to develop screening policies in Mexico.
Methods: We screened 810 unselected women with breast cancer from three cities in Mexico (Mexico City, Veracruz, and Monterrey) for mutations in BRCA1 and BRCA2, including a panel of 26 previously reported mutations.
Results: Thirty-five mutations were identified in 34 women (4.3% of total) including 20 BRCA1 mutations and 15 BRCA2 mutations. Twenty-two of the 35 mutations were recurrent mutations (62.8%). Only five of the 34 mutation carriers had a first-degree relative with breast cancer (three with BRCA1 and two with BRCA2 mutations).
Conclusion: These results support the rationale for a strategy of screening for recurrent mutations in all women with breast cancer in Mexico, as opposed to restricting screening to those with a sister or mother with breast or ovarian cancer.
Background: Prior randomized, controlled trials (RCTs) indicate that patient navigation can boost colorectal cancer screening rates in primary care. The sparse literature on pragmatic trials of interventions designed to increase colorectal cancer screening adherence motivated this trial on the impact of a patient navigation intervention that included support for performance of the participants' preferred screening test (colonoscopy or stool blood testing).
Materials and Methods: Primary care patients (n = 5,240), 50 to 74 years of age, with no prior diagnosis of bowel cancer and no record of a recent colorectal cancer screening test, were identified at the Group Health Centre in northern Ontario. These patients were randomly assigned to an intervention group (n = 2,629) or a usual care control group (n = 2,611). Intervention group participants were contacted by a trained nurse navigator by telephone to discuss colorectal cancer screening. Interested patients met with the navigator, who helped them identify and arrange for performance of the preferred screening test. Control group participants received usual care. Multivariate analyses were conducted using medical records data to assess intervention impact on screening adherence within 12 months after randomization.
Results: Mean patient age was 59 years, and 50% of participants were women. Colorectal cancer screening adherence was higher in the intervention group (35%) than in the control group (20%), a difference that was statistically significant (OR, 2.11; confidence interval, 1.87–2.39).
Conclusion: Preference-based patient navigation increased screening uptake in a pragmatic RCT.
Background: The CpG island methylator phenotype (CIMP) represents a subset of colorectal cancers characterized by widespread aberrant DNA hypermethylation at select CpG islands. The risk factors and environmental exposures contributing to etiologic heterogeneity between CIMP and non-CIMP tumors are not known.
Methods: We measured the CIMP status of 3,119 primary population-based colorectal cancer tumors from the multinational Colon Cancer Family Registry. Etiologic heterogeneity was assessed by a case–case study comparing risk factor frequency of colorectal cancer cases with CIMP and non-CIMP tumors using logistic regression to estimate the case–case odds ratio (ccOR).
Results: We found associations between tumor CIMP status and MSI-H (ccOR = 7.6), BRAF V600E mutation (ccOR = 59.8), proximal tumor site (ccOR = 9; all P < 0.0001), female sex [ccOR = 1.8; 95% confidence interval (CI), 1.5–2.1], older age (ccOR = 4.0 comparing over 70 years vs. under 50; 95% CI, 3.0–5.5), and family history of CRC (ccOR = 0.6; 95% CI, 0.5–0.7). While use of NSAIDs varied by tumor CIMP status for both males and females (P = 0.0001 and P = 0.02, respectively), use of multivitamin or calcium supplements did not. Only for female colorectal cancer was CIMP status associated with increased pack-years of smoking (Ptrend < 0.001) and body mass index (BMI; Ptrend = 0.03).
Conclusions: The frequency of several colorectal cancer risk factors varied by CIMP status, and the associations of smoking and obesity with tumor subtype were evident only for females.
Background: The etiology of male breast cancer is poorly understood, partly due to its relative rarity. Although tobacco and alcohol exposures are known carcinogens, their association with male breast cancer risk remains ill-defined.
Methods: The Male Breast Cancer Pooling Project consortium provided 2,378 cases and 51,959 controls for analysis from 10 case–control and 10 cohort studies. Individual participant data were harmonized and pooled. Unconditional logistic regression was used to estimate study design–specific (case–control/cohort) ORs and 95% confidence intervals (CI), which were then combined using fixed-effects meta-analysis.
Results: Cigarette smoking status, smoking pack-years, duration, intensity, and age at initiation were not associated with male breast cancer risk. Relations with cigar and pipe smoking, tobacco chewing, and snuff use were also null. Recent alcohol consumption and average grams of alcohol consumed per day were also not associated with risk; only one subanalysis of very high recent alcohol consumption (>60 g/day) was tentatively associated with male breast cancer (ORunexposed referent = 1.29; 95% CI, 0.97–1.71; OR>0–<7 g/day referent = 1.36; 95% CI, 1.04–1.77). Specific alcoholic beverage types were not associated with male breast cancer. Relations were not altered when stratified by age or body mass index.
Conclusions: In this analysis of the Male Breast Cancer Pooling Project, we found little evidence that tobacco and alcohol exposures were associated with risk of male breast cancer.
Background: Evidence suggests that estrogen plays a preventive role in primary liver cancer development, and it might be thought that isoflavones, which are structurally similar to estrogens and bind to estrogen receptors, are associated with the risk of liver cancer. We investigated this suspected association by measuring plasma concentrations of isoflavones in a nested case–control study of a population-based prospective cohort in Japan.
Methods: From 18,628 target participants ages 40 to 69 years who returned the baseline questionnaire and provided blood samples, we selected those with either hepatitis B or hepatitis C virus infection at baseline (n = 1,544). Among these, 90 (28 women and 62 men) were newly diagnosed with primary liver cancer from 1993 through 2006; they were matched with 175 controls (54 women and 121 men). Plasma concentrations of isoflavones (genistein, daidzein, glycitein, and equol) were measured using triple quadrupole tandem liquid chromatography-mass spectrometry. The ORs of liver cancer development based on plasma concentrations were estimated with a conditional logistic regression model.
Results: Basically, distributions of plasma isoflavone concentrations did not differ between the cases and controls. No statistically significant associations of genistein, daidzein, glycitein, and equol with primary liver cancer risk were found in either women or men.
Conclusions: In middle-aged Japanese women and men with hepatitis virus infection, plasma isoflavones were unassociated with the occurrence of primary liver cancer.
Background: Chronic lymphocytic leukemia (CLL) is a chronic disease that often progresses slowly from a precursor stage, monoclonal B-cell lymphocytosis (MBL), and that can remain undiagnosed for a long time.
Methods: Within the European Prospective Investigation into Cancer cohort, we measured prediagnostic plasma sCD23 for 179 individuals who eventually were diagnosed with CLL and an equal number of matched control subjects who remained free of cancer.
Results: In a very large proportion of CLL patients' plasma sCD23 was clearly elevated 7 or more years before diagnosis. Considering sCD23 as a disease predictor, the area under the ROC curve (AUROC) was 0.95 [95% confidence interval (CI), 0.90–1.00] for CLL diagnosed within 0.1 to 2.7 years after blood measurement, 0.90 (95% CI, 0.86–0.95) for diagnosis within 2.8 to 7.3 years, and 0.76 (95% CI, 0.65–0.86) for CLL diagnosed between 7.4 and 12.5 years. Even at a 7.4-year and longer time interval, elevated plasma sCD23 could predict a later clinical diagnosis of CLL with 100% specificity at >45% sensitivity.
Conclusions: Our findings provide unique documentation for the very long latency times during which measurable B-cell lymphoproliferative disorder exists before the clinical manifestation of CLL.
Background: Lignans in plant foods are metabolized by gut bacteria to the enterolignans, enterodiol (END) and enterolactone (ENL). Enterolignans have biologic activities important to the prevention of cancer and chronic diseases. We examined the composition of the gut microbial community (GMC) as a contributor to human enterolignan exposure.
Methods: We evaluated the association between the GMC in stool, urinary enterolignan excretion, and diet from a 3-day food record in 115 premenopausal (ages 40–45 years) women in the United States. Urinary enterolignans were measured using gas chromatography–mass spectroscopy. The GMC was evaluated using 454 pyrosequencing of the 16S rRNA gene. Sequences were aligned in SILVA (www.arb-silva.de). Operational taxonomic units were identified at 97% sequence similarity. Taxonomic classification was performed and alpha and beta diversity in relationship to ENL production were assessed. Multivariate analysis and regression were used to model the association between enterolignan excretion and the GMC. Bacteria associated with ENL production were identified using univariate analysis and ridge regression.
Results: After adjusting for dietary fiber intake and adiposity, we found a significant positive association between ENL excretion and either the GMC (P = 0.0007), or the diversity of the GMC (P = 0.01). The GMC associated with high ENL production was distinct (UNIFRAC, P < 0.003, MRPP) and enriched in Moryella spp., Acetanaerobacterium spp., Fastidiosipila spp., and Streptobacillus spp.
Conclusion: Diversity and composition of the GMC are associated with increased human exposure to enterolignans.
Background: Although interventional trials demonstrated that moderate-dose β-carotene supplementation increases lung cancer mortality in smokers and asbestos-exposed workers, differences in serum concentrations in absence of supplementation have not been studied in asbestos-exposed workers.
Methods: A mortality analysis was performed to assess the relationship of nonsupplemented serum β-carotene to all-cause and cancer mortalities using 1981 to 1983 serum β-carotene concentration measurements from 2,646 U.S. white male insulators (mean age, 57.7 years). Multivariable-adjusted Cox proportional hazard models that included terms for age, duration of asbestos exposure, smoking, season, and region were fitted to estimate mortality HRs and 95% confidence intervals (CI) according to serum β-carotene concentrations.
Results: Median follow-up was 12.8 years and 984 (33.8%) subjects died during the follow-up period, including 415 deaths from overall cancer and 219 deaths from lung cancer. The overall mortality HR for a serum β-carotene increase of 10 μg/dL was 0.97 (95% CI, 0.96–0.99). Compared with the lowest quartile, HRs were 0.90 (95% CI, 0.76–1.07) for the second (38–65 μg/dL), 0.80 (95% CI, 0.67–0.96) for the third (66–104 μg/dL), and 0.63 (95% CI, 0.51–0.77) for the highest serum β-carotene quartile (≥105 μg/dL). There was no association between serum β-carotene and overall cancer mortality (HR, 1.00; 95% CI, 0.97–1.02) or lung cancer mortality (HR, 0.99; 95% CI, 0.96–1.02).
Conclusions: Higher nonsupplemented serum β-carotene concentrations were negatively associated with all-cause mortality among asbestos-exposed individuals.
Background: Results of the Multiethnic Cohort (MEC) study demonstrated that, for the same quantity of cigarettes smoked, African Americans and Native Hawaiians have a higher risk of lung cancer compared with whites, whereas Latinos and Japanese Americans have a lower risk. We hypothesize that the uptake and/or metabolism of the lung carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) could explain the differences in lung cancer risk.
Methods: We measured urinary 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and its glucuronides and their sum (total NNAL), biomarkers of NNK uptake, in 2,252 smokers from the MEC. Ethnic-specific geometric means were compared adjusting for age at urine collection, sex, creatinine and total nicotine equivalents, a marker of total nicotine uptake.
Results: African Americans had the highest median total NNAL levels (1.80 pmol/mL urine) and Japanese Americans had the lowest (0.914 pmol/mL urine), with intermediate values in the other three groups. Geometric mean of total NNAL in African Americans was also highest, and in Japanese Americans it was lowest; Japanese American geometric mean was statistically different from whites (P = 0.004).
Conclusions: African Americans had higher levels of total NNAL per mL urine than whites, while Japanese Americans had lower levels, consistent with lung cancer risk among smokers in these groups. However, our data were not consistent with the high and low lung cancer risks of Native Hawaiian and Latino smokers, respectively.
Background: Occupational exposures are known risk factors for lung cancer. Role of genetically determined host factors in occupational exposure–related lung cancer is unclear.
Methods: We used genome-wide association (GWA) data from a case–control study conducted in 6 European countries from 1998 to 2002 to identify gene–occupation interactions and related pathways for lung cancer risk. GWA analysis was performed for each exposure using logistic regression and interaction term for genotypes, and exposure was included in this model. Both SNP-based and gene-based interaction P values were calculated. Pathway analysis was performed using three complementary methods, and analyses were adjusted for multiple comparisons. We analyzed 312,605 SNPs and occupational exposure to 70 agents from 1,802 lung cancer cases and 1,725 cancer-free controls.
Results: Mean age of study participants was 60.1 ± 9.1 years and 75% were male. Largest number of significant associations (P ≤ 1 x 10–5) at SNP level was demonstrated for nickel, brick dust, concrete dust, and cement dust, and for brick dust and cement dust at the gene-level (P ≤ 1 x 10–4). Approximately 14 occupational exposures showed significant gene–occupation interactions with pathways related to response to environmental information processing via signal transduction (P < 0.001 and FDR < 0.05). Other pathways that showed significant enrichment were related to immune processes and xenobiotic metabolism.
Conclusion: Our findings suggest that pathways related to signal transduction, immune process, and xenobiotic metabolism may be involved in occupational exposure–related lung carcinogenesis.
Background: Although obesity is associated with breast cancer incidence and prognosis, the underlying mechanisms are poorly understood. Identification of obesity-associated epigenetic changes in breast tissue may advance mechanistic understanding of breast cancer initiation and progression. The goal of this study, therefore, was to investigate associations between obesity and gene methylation in breast tumors.
Methods: Using the Illumina GoldenGate Cancer I Panel, we estimated the association between body mass index (BMI) and gene methylation in 345 breast tumor samples from phase I of the Carolina Breast Cancer Study, a population-based case–control study. Multivariable linear regression was used to identify sites that were differentially methylated by BMI. Stratification by tumor estrogen receptor (ER) status was also conducted.
Results: In the majority of the 935 probes analyzed (87%), the average beta value increased with obesity (BMI ≥ 30). Obesity was significantly associated with differential methylation (FDR q < 0.05) in just two gene loci in breast tumor tissue overall and in 21 loci among ER-positive tumors. Obesity was associated with methylation of genes that function in immune response, cell growth, and DNA repair.
Conclusions: Obesity is associated with altered methylation overall, and with hypermethylation among ER-positive tumors in particular, suggesting that obesity may influence the methylation of genes with known relevance to cancer. Some of these differences in methylation by obese status may influence levels of gene expression within breast cells.
Background: Because of unique exposures, studies among farmers may yield insights into the relationship between allergies and non-Hodgkin lymphoid (NHL) neoplasms. We evaluated farm characteristics, allergic symptoms and conditions, and risk of NHL including specific subtypes in the Agricultural Health Study, a prospective cohort of farmers and spouses from North Carolina and Iowa.
Methods: We identified 710 incident cases of NHL (including chronic lymphocytic leukemia and multiple myeloma) among 82,370 participants with baseline data on crop and animal exposures, including 454 cases among 52,850 participants with baseline data on recent allergy symptoms (rhinitis) and living on a farm during childhood. HR and 95% confidence intervals (CI) were calculated using multivariable-adjusted proportional hazards models.
Results: We observed reduced risks of NHL among farmers and spouses with rhinitis at baseline (HR, 0.63; 95% CI, 0.51–0.79), related to growing soybeans (HR, 0.80; 95% CI, 0.67–0.96), and among farmers who handled stored grains or hay (HR, 0.66; 95% CI, 0.52–0.82). Growing up on a farm was associated with increased NHL risk (HR, 1.51; 95% CI, 1.15–1.98). Results did not differ significantly by NHL subtype.
Conclusions: Both the reduced risk of NHL among those with allergy symptoms and specific farm exposures in adulthood, and the increased risk among those who grew up on a farm suggest that the host immune response to agricultural allergens may influence NHL development.
Background: Human papillomavirus (HPV) vaccination coverage is far below the national objective set by Healthy People 2020. This paper explores spatial patterns in HPV vaccination uptake.
Methods: Secondary data for publicly funded HPV vaccinations among age-eligible children from 2008 through 2013 from the North Carolina Immunization Registry (NCIR) were used in 2014 in an ecological analysis at the ZIP code tabulation area (ZCTA) level. We tested for spatial autocorrelation in unadjusted HPV vaccination rates using choropleth maps and Moran's I. We estimated nonspatial and spatial negative binomial models with spatially correlated random effects adjusted for demographic, economic, and healthcare variables drawn from the 2010 U.S. Census Bureau, 2008–2012 American Community Survey, 2010 ZIP Business Patterns, and the 2012–2013 Area Resource File.
Results: The NCIR revealed areas of especially low rates in publicly funded HPV vaccinations among uninsured and means-tested, publicly insured children. For boys, but not girls, ZCTAs tended to have HPV vaccination rates that were similar to their neighbors. This result was partially explained by included ZCTA characteristics, but not wholly.
Conclusions: To the extent that the geospatial clustering of vaccination rates is due to causal influences from one ZCTA to another (e.g., through information networks), targeting interventions to increase HPV vaccination in one area could also lead to increases in neighboring areas.
Background: Baseline prognostic biomarkers stratifying treatment strategies in first-line metastatic colorectal cancer (mCRC) are lacking. Angiopoietin-2 (Ang-2) is proposed as a potential biomarker in several cancers. We therefore decided to establish the additional prognostic value of Ang-2 for overall survival (OS) in patients with first-line mCRC.
Methods: We enrolled 177 patients treated with a bevacizumab containing chemotherapy in two prospective phase II clinical trials. Patient plasma samples were collected at baseline. ELISAs were used to measure Ang-2.
Results: The multivariable Cox model identified increased lactate dehydrogenase [HR, 1.60; 95% confidence interval (CI), 1.04–2.45; P = 0.03] and Ang-2 log-transformation level (HR, 1.59; 95% CI, 1.14–2.21; P = 0.0065) as two significant independent OS prognostic factors. It exhibited good calibration (P = 0.8) and discrimination (C-index: 0.64; 95% CI, 0.58–0.68). Ang-2 parameter inclusion in the GERCOR reference model significantly and strongly improved its discriminative ability because the C-statistic increased significantly from 0.61 to 0.63 (bootstrap mean difference = 0.07; 95% CI, 0.069–0.077). Interestingly, the addition of Ang-2 binary information with a 5 ng/mL cutoff value to the GERCOR model allowed the reclassification of intermediate-risk profile patients (41%) into two subsets of low and high risks.
Conclusions: Our study provides robust evidence in favor of baseline Ang-2 prognostic value for OS adding to the conventional factors. Its assessment appears to be useful for the improvement in risk stratification for patients with intermediate-risk profile.
Background: While several studies have provided support for a positive association between meat intake and colorectal neoplasia, the role of heterocyclic amines (HCA), which is hypothesized to underline this relation, has been less consistent. We evaluated the association of HCA intake with colorectal adenoma risk in a case–control study in a middle-aged Japanese population.
Methods: Study subjects were 738 patients with adenoma and 697 controls who underwent total colonoscopy between 2004 and 2005 and responded to self-administered lifestyle and dietary questionnaires. HCA exposure concentration was estimated from meat and fish intake based on an HCA database that was validated against 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) values measured in human hair. Logistic regression models were used to estimate ORs and 95% confidence interval (CI) for the association between HCA and colorectal adenoma risk after adjusting for potential confounders.
Results: High intake of 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) and total HCA was associated with an increased risk of colorectal adenoma in women but not in men. The multivariate-adjusted OR for the highest versus lowest quartile in women was 2.10 (95% CI, 1.20–3.67; Ptrend = 0.01) for MeIQ and 1.73 (95% CI, 0.99–3.01; Ptrend = 0.03) for total HCA. No clear association with PhIP or 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) estimates and no effect modification by NAT2 acetylation genotype was observed.
Conclusions: This study suggests that high MeIQ and total HCA estimates are positively associated with colorectal adenoma risk.
Background: Two recent genome-wide association studies (GWAS) identified SNPs in or near four genes related to circulating 25-hydroxyvitamin D [25(OH)D] concentration. To examine the hypothesized inverse relationship between vitamin D status and breast cancer, we studied the associations between SNPs in these genes and breast cancer risk in a large pooled study of 9,456 cases and 10,816 controls from six cohorts.
Methods: SNP markers localized to each of four genes (GC, CYP24A1, CYP2R1, and DHCR7) previously associated with 25(OH)D were genotyped and examined both individually and as a 4-SNP polygenic score. Logistic regression was used to estimate the associations between the genetic variants and risk of breast cancer.
Results: We found no association between any of the four SNPs or their polygenic score and breast cancer risk.
Conclusions: Our findings do not support an association between vitamin D status, as reflected by 25(OH)D–related genotypes, and breast cancer risk.
Background: Past investigations of cigarette smoking and multiple myeloma have been underpowered to detect moderate associations, particularly within subgroups. To clarify this association, we conducted a pooled analysis of nine case–control studies in the International Multiple Myeloma Consortium, with individual-level questionnaire data on cigarette smoking history and other covariates.
Methods: Using a pooled population of 2,670 cases and 11,913 controls, we computed odds ratios (OR) and 95% confidence intervals (CI) relating smoking to multiple myeloma risk using unconditional logistic regression adjusting for gender, age group, race, education, body mass index, alcohol consumption, and study center.
Results: Neither ever smokers (OR, 0.95; 95% CI, 0.87–1.05), current smokers (OR, 0.82; 95% CI, 0.73–0.93), nor former smokers (OR, 1.03; 95% CI, 0.92–1.14) had increased risks of multiple myeloma compared with never smokers. Analyses of smoking frequency, pack-years, and duration did not reveal significant or consistent patterns, and there was no significant effect modification by subgroups.
Conclusion: Findings from this large pooled analysis do not support the hypothesis of cigarette smoking as a causal factor for multiple myeloma.