BRCA2 Polymorphic Stop Codon K3326X and the Risk of Breast, Prostate, and Ovarian Cancers

BACKGROUND

The K3326X variant in BRCA2 (BRCA2*c.9976A>T; p.Lys3326*; rs11571833) has been found to be associated with small increased risks of breast cancer. However, it is not clear to what extent linkage disequilibrium with fully pathogenic mutations might account for this association. There is scant information about the effect of K3326X in other hormone-related cancers.

METHODS

Using weighted logistic regression, we analyzed data from the large iCOGS study including 76 637 cancer case patients and 83 796 control patients to estimate odds ratios (ORw) and 95% confidence intervals (CIs) for K3326X variant carriers in relation to breast, ovarian, and prostate cancer risks, with weights defined as probability of not having a pathogenic BRCA2 variant. Using Cox proportional hazards modeling, we also examined the associations of K3326X with breast and ovarian cancer risks among 7183 BRCA1 variant carriers. All statistical tests were two-sided.

RESULTS

The K3326X variant was associated with breast (ORw = 1.28, 95% CI = 1.17 to 1.40, P = 5.9x10(-) (6)) and invasive ovarian cancer (ORw = 1.26, 95% CI = 1.10 to 1.43, P = 3.8x10(-3)). These associations were stronger for serous ovarian cancer and for estrogen receptor-negative breast cancer (ORw = 1.46, 95% CI = 1.2 to 1.70, P = 3.4x10(-5) and ORw = 1.50, 95% CI = 1.28 to 1.76, P = 4.1x10(-5), respectively). For BRCA1 mutation carriers, there was a statistically significant inverse association of the K3326X variant with risk of ovarian cancer (HR = 0.43, 95% CI = 0.22 to 0.84, P = .013) but no association with breast cancer. No association with prostate cancer was observed.

CONCLUSIONS

Our study provides evidence that the K3326X variant is associated with risk of developing breast and ovarian cancers independent of other pathogenic variants in BRCA2. Further studies are needed to determine the biological mechanism of action responsible for these associations.

Abstract B40: Prediagnosis leukocyte telomere length and risk of ovarian cancer

Introduction: Ovarian cancer is characterized by substantial genomic instability. Telomeres, which protect the physical integrity of chromosomes, are shortened by each cell division, and evidence supports that longer telomeres may reduce genomic instability. While retrospective studies generally support an inverse association of telomere length and ovarian cancer risk, the measures of telomere length after diagnosis may be influenced by treatment. Therefore, we examined the relationship between leukocyte telomere length (LTL) assessed prior to diagnosis and risk of ovarian cancer in three prospective studies.

Methods: We used buffy coat samples collected from healthy participants in the Nurses' Health Study (NHS), NHSII, and the Northern Sweden Health and Disease Study (NSHDS). Women who later developed ovarian cancer were matched to one or two controls on age, menopausal status, and date of blood collection. LTL was assessed using quantitative PCR-based assays in 5 batches with coefficients of variation of 10-15%. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using conditional logistic regression, based on study-specific quartiles in controls, for each study separately. We used fixed-effects models for meta-analysis. Multivariate models adjusted for oral contraceptive use, tubal ligation, family history of ovarian cancer, parity, smoking status, and body mass index.

Results: In total, there were 487 cases and 810 controls across the three studies. The mean age at blood collection ranged from 45 (NHSII) to 57 (NHS) years. In unadjusted and multivariate models, we observed a suggestion of an inverse association between LTL and ovarian cancer risk in each study, although none of the trend tests were statistically significant. In a meta-analysis of the multivariate adjusted models, women in the longest versus shortest quartile of LTL had a non-significant 26% lower risk of ovarian cancer (OR=0.74; 95%CI=0.49-1.12; p-trend=0.33).

Conclusion: In this first prospective study of telomere length and ovarian cancer risk, we observed that longer leukocyte telomere length was suggestively associated with lower ovarian cancer risk. Given that serous tumors are more likely to exhibit genomic instability, we are currently evaluating the association for this subtype as well as conducting pooled analyses with common quartile cut points across studies.

Citation Format: Meng Yang, Jennifer Prescott, Elizabeth M. Poole, Megan S. Rice, Annika Idahl, Eva Lundin, Immaculata De Vivo, Shelley S. Tworoger. Prediagnosis leukocyte telomere length and risk of ovarian cancer. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr B40.

Post-diagnosis social networks, and lifestyle and treatment factors in the After Breast Cancer Pooling Project

OBJECTIVE

Larger social networks have been associated with better breast cancer survival. To investigate potential mediators, we evaluated associations of social network size and diversity with lifestyle and treatment factors associated with prognosis.

METHODS

We included 9331 women from the After Breast Cancer Pooling Project who provided data on social networks within approximately two years following diagnosis. A social network index was derived from information about the presence of a spouse or intimate partner, religious ties, community participation, friendship ties, and numbers of living relatives. Diversity was assessed as variety of ties, independent of size. We used logistic regression to evaluate associations with outcomes and evaluated whether effect estimates differed using meta-analytic techniques.

RESULTS

Associations were similar across cohorts though analyses of smoking and alcohol included US cohorts only because of low prevalence of these behaviors in the Shanghai cohort. Socially isolated women were more likely to be obese (OR = 1.21, 95% CI:1.03-1.42), have low physical activity (<10 MET-hours/week, OR = 1.55, 95% CI:1.36-1.78), be current smokers (OR = 2.77, 95% CI:2.09-3.68), and have high alcohol intake (≥15 g/d, OR = 1.23, 95% CI:1.00-1.51), compared with socially integrated women. Among node positive cases from three cohorts, socially isolated women were more likely not to receive chemotherapy (OR = 2.10, 95% CI:1.30-3.39); associations differed in a fourth cohort. Other associations (nonsignificant) were consistent with less intensive treatment in socially isolated women. Low social network diversity was independently associated with more adverse lifestyle, but not clinical, factors.

CONCLUSIONS

Small, less diverse social networks measured post-diagnosis were associated with more adverse lifestyle factors and less intensive cancer treatment. Copyright © 2016 John Wiley & Sons, Ltd.

A pooled analysis of post-diagnosis lifestyle factors in association with late estrogen-receptor-positive breast cancer prognosis

Lifestyle factors have been well studied in relation to breast cancer prognosis overall; however, associations of lifestyle and late outcomes (>5 years after diagnosis) have been much less studied, and no studies have focused on estrogen receptor-positive (ER+) breast cancer survivors, who may have high risk of late recurrence and mortality. We utilized a large prospective pooling study to evaluate the associations of lifestyle factors with late recurrence and all-cause mortality among 6,295 5-year ER+ Stage I-III breast cancer survivors. Pooled and harmonized data were available on clinical factors and lifestyle factors (pre- to post-diagnosis weight change, body mass index (BMI) (kg/m(2)), recreational physical activity, alcohol intake and smoking history), measured on average 2.1 years after diagnosis. Updated information for weight only was available. Study heterogeneity was evaluated by the Q-statistic. Multivariable Cox regression models were stratified by study. Adjusting for clinical factors and potential confounders, ≥ 10% weight gain and obesity (BMI, 30-34.99 and ≥ 35) were associated with increased risk of late recurrence (hazard ratios (95% confidence intervals): 1.24 (1.00-1.53), 1.40 (1.05-1.86) and 1.41 (1.02-1.93), respectively). Daily alcohol intake was associated with late recurrence, 1.28 (1.01-1.62). Physical activity was inversely associated with late all-cause mortality (0.81 (0.71-0.93) and 0.71 (0.61-0.82) for 4.9 to <17.4 and ≥ 17.4 metabolic equivalent-hr/week). A U-shaped association was observed for late all-cause mortality and BMI using updated weight (1.42 (1.15-1.74) and 1.40 (1.09-1.81), <21.5 and ≥ 35, respectively). Smoking was associated with increased risk of late outcomes. In this large prospective pooling project, modifiable lifestyle factors were associated with late outcomes among long-term ER+ breast cancer survivors.

Epithelial-Mesenchymal Transition (EMT) Gene Variants and Epithelial Ovarian Cancer (EOC) Risk

Epithelial-mesenchymal transition (EMT) is a process whereby epithelial cells assume mesenchymal characteristics to facilitate cancer metastasis. However, EMT also contributes to the initiation and development of primary tumors. Prior studies that explored the hypothesis that EMT gene variants contribute to epithelial ovarian carcinoma (EOC) risk have been based on small sample sizes and none have sought replication in an independent population. We screened 15,816 single-nucleotide polymorphisms (SNPs) in 296 genes in a discovery phase using data from a genome-wide association study of EOC among women of European ancestry (1,947 cases and 2,009 controls) and identified 793 variants in 278 EMT-related genes that were nominally (P < 0.05) associated with invasive EOC. These SNPs were then genotyped in a larger study of 14,525 invasive-cancer patients and 23,447 controls. A P-value <0.05 and a false discovery rate (FDR) <0.2 were considered statistically significant. In the larger dataset, GPC6/GPC5 rs17702471 was associated with the endometrioid subtype among Caucasians (odds ratio (OR) = 1.16, 95% CI = 1.07-1.25, P = 0.0003, FDR = 0.19), whereas F8 rs7053448 (OR = 1.69, 95% CI = 1.27-2.24, P = 0.0003, FDR = 0.12), F8 rs7058826 (OR = 1.69, 95% CI = 1.27-2.24, P = 0.0003, FDR = 0.12), and CAPN13 rs1983383 (OR = 0.79, 95% CI = 0.69-0.90, P = 0.0005, FDR = 0.12) were associated with combined invasive EOC among Asians. In silico functional analyses revealed that GPC6/GPC5 rs17702471 coincided with DNA regulatory elements. These results suggest that EMT gene variants do not appear to play a significant role in the susceptibility to EOC.

Statistical methods for studying disease subtype heterogeneity

A fundamental goal of epidemiologic research is to investigate the relationship between exposures and disease risk. Cases of the disease are often considered a single outcome and assumed to share a common etiology. However, evidence indicates that many human diseases arise and evolve through a range of heterogeneous molecular pathologic processes, influenced by diverse exposures. Pathogenic heterogeneity has been considered in various neoplasms such as colorectal, lung, prostate, and breast cancers, leukemia and lymphoma, and non-neoplastic diseases, including obesity, type II diabetes, glaucoma, stroke, cardiovascular disease, autism, and autoimmune disease. In this article, we discuss analytic options for studying disease subtype heterogeneity, emphasizing methods for evaluating whether the association of a potential risk factor with disease varies by disease subtype. Methods are described for scenarios where disease subtypes are categorical and ordinal and for cohort studies, matched and unmatched case-control studies, and case-case study designs. For illustration, we apply the methods to a molecular pathological epidemiology study of alcohol intake and colon cancer risk by tumor LINE-1 methylation subtypes. User-friendly software to implement the methods is publicly available.

Common variants at the CHEK2 gene locus and risk of epithelial ovarian cancer

Genome-wide association studies have identified 20 genomic regions associated with risk of epithelial ovarian cancer (EOC), but many additional risk variants may exist. Here, we evaluated associations between common genetic variants [single nucleotide polymorphisms (SNPs) and indels] in DNA repair genes and EOC risk. We genotyped 2896 common variants at 143 gene loci in DNA samples from 15 397 patients with invasive EOC and controls. We found evidence of associations with EOC risk for variants at FANCA, EXO1, E2F4, E2F2, CREB5 and CHEK2 genes (P ≤ 0.001). The strongest risk association was for CHEK2 SNP rs17507066 with serous EOC (P = 4.74 x 10(-7)). Additional genotyping and imputation of genotypes from the 1000 genomes project identified a slightly more significant association for CHEK2 SNP rs6005807 (r (2) with rs17507066 = 0.84, odds ratio (OR) 1.17, 95% CI 1.11-1.24, P = 1.1×10(-7)). We identified 293 variants in the region with likelihood ratios of less than 1:100 for representing the causal variant. Functional annotation identified 25 candidate SNPs that alter transcription factor binding sites within regulatory elements active in EOC precursor tissues. In The Cancer Genome Atlas dataset, CHEK2 gene expression was significantly higher in primary EOCs compared to normal fallopian tube tissues (P = 3.72×10(-8)). We also identified an association between genotypes of the candidate causal SNP rs12166475 (r (2) = 0.99 with rs6005807) and CHEK2 expression (P = 2.70×10(-8)). These data suggest that common variants at 22q12.1 are associated with risk of serous EOC and CHEK2 as a plausible target susceptibility gene.

Shared genetics underlying epidemiological association between endometriosis and ovarian cancer

Epidemiological studies have demonstrated associations between endometriosis and certain histotypes of ovarian cancer, including clear cell, low-grade serous and endometrioid carcinomas. We aimed to determine whether the observed associations might be due to shared genetic aetiology. To address this, we used two endometriosis datasets genotyped on common arrays with full-genome coverage (3194 cases and 7060 controls) and a large ovarian cancer dataset genotyped on the customized Illumina Infinium iSelect (iCOGS) arrays (10 065 cases and 21 663 controls). Previous work has suggested that a large number of genetic variants contribute to endometriosis and ovarian cancer (all histotypes combined) susceptibility. Here, using the iCOGS data, we confirmed polygenic architecture for most histotypes of ovarian cancer. This led us to evaluate if the polygenic effects are shared across diseases. We found evidence for shared genetic risks between endometriosis and all histotypes of ovarian cancer, except for the intestinal mucinous type. Clear cell carcinoma showed the strongest genetic correlation with endometriosis (0.51, 95% CI = 0.18-0.84). Endometrioid and low-grade serous carcinomas had similar correlation coefficients (0.48, 95% CI = 0.07-0.89 and 0.40, 95% CI = 0.05-0.75, respectively). High-grade serous carcinoma, which often arises from the fallopian tubes, showed a weaker genetic correlation with endometriosis (0.25, 95% CI = 0.11-0.39), despite the absence of a known epidemiological association. These results suggest that the epidemiological association between endometriosis and ovarian adenocarcinoma may be attributable to shared genetic susceptibility loci.

Depression and risk of epithelial ovarian cancer: Results from two large prospective cohort studies

OBJECTIVES

While emerging evidence supports a possible link between depression and ovarian cancer progression, no prospective studies have explored the association with ovarian cancer risk.

METHODS

We prospectively followed 77,451 women from the Nurses' Health Study (1992-2010) and 106,452 women from the Nurses' Health Study II (1993-2011). Depression was defined as having one or more of the following: a 5-item Mental Health Index (MHI-5) score≤52, antidepressant use, or physician-diagnosed depression. Multivariable-adjusted Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between depression and incident ovarian cancer.

RESULTS

We documented 698 incident cases of epithelial ovarian cancer during follow-up. In multivariable analyses, depression assessed 2-4years before cancer diagnosis was associated with a modestly higher incidence of ovarian cancer (HR=1.30, 95% CI 1.05-1.60). Compared to women with persistent negative depression status, the adjusted HRs were 1.34 (95% CI 1.01-1.76) for women with persistent positive depression status and 1.28 (95% CI 0.88-1.85) for women with worsening depression status over follow-up. The association did not appear to vary by ovarian cancer risk factors or tumor characteristics.

CONCLUSIONS

Our findings suggest that depression may be associated with a modestly increased risk of ovarian cancer. Given the relatively high prevalence of depression in women, future work in larger prospective human studies is needed to confirm our results.

Network-Based Integration of GWAS and Gene Expression Identifies a HOX-Centric Network Associated with Serous Ovarian Cancer Risk

BACKGROUND

Genome-wide association studies (GWAS) have so far reported 12 loci associated with serous epithelial ovarian cancer (EOC) risk. We hypothesized that some of these loci function through nearby transcription factor (TF) genes and that putative target genes of these TFs as identified by coexpression may also be enriched for additional EOC risk associations.

METHODS

We selected TF genes within 1 Mb of the top signal at the 12 genome-wide significant risk loci. Mutual information, a form of correlation, was used to build networks of genes strongly coexpressed with each selected TF gene in the unified microarray dataset of 489 serous EOC tumors from The Cancer Genome Atlas. Genes represented in this dataset were subsequently ranked using a gene-level test based on results for germline SNPs from a serous EOC GWAS meta-analysis (2,196 cases/4,396 controls).

RESULTS

Gene set enrichment analysis identified six networks centered on TF genes (HOXB2, HOXB5, HOXB6, HOXB7 at 17q21.32 and HOXD1, HOXD3 at 2q31) that were significantly enriched for genes from the risk-associated end of the ranked list (P < 0.05 and FDR < 0.05). These results were replicated (P < 0.05) using an independent association study (7,035 cases/21,693 controls). Genes underlying enrichment in the six networks were pooled into a combined network.

CONCLUSION

We identified a HOX-centric network associated with serous EOC risk containing several genes with known or emerging roles in serous EOC development.

IMPACT

Network analysis integrating large, context-specific datasets has the potential to offer mechanistic insights into cancer susceptibility and prioritize genes for experimental characterization.

A prospective study of leisure-time physical activity and risk of incident epithelial ovarian cancer: Impact by menopausal status

Despite multiple hypotheses for a protective effect, epidemiologic findings are inconsistent regarding the association between physical activity and risk of ovarian cancer. Considering physical activity assessment at different times of life, including pre- and postmenopause, may be important for explaining these discrepancies. Therefore, we examined the risk of ovarian cancer according to total, premenopausal and postmenopausal physical activity among 85,462 women from the Nurses' Health Study and 112,679 women from the Nurses' Health Study II. Leisure-time physical activity was prospectively assessed about every 2-4 years using validated questionnaires, and characterized as metabolic equivalent task hours per week (MET-hr/week), which combines exercise duration and intensity. Multivariable Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for these associations. We identified 815 incident epithelial ovarian cancer cases during 24 years of follow-up. A modestly increased ovarian cancer risk was observed for high levels of total cumulative average physical activity and a suggestively increased risk for low activity. Compared to 3-9 MET-hr/week, HRs (95% CIs) were 1.26 (1.02, 1.55) for ≥ 27 MET-hr/week (equivalent to 1 hr/day of brisk walking) and 1.19 (0.94, 1.52) for <3 MET-hr/week. This association was limited to premenopausal physical activity [comparable HR (95% CI) of 1.50 (1.13, 1.97) and 1.29 (0.95, 1.75), respectively]. Postmenopausal physical activity was not associated with risk. Our data do not support a protective role of physical activity for ovarian cancer. The increased risk associated with physical activity during premenopausal years and the underlying etiology require further investigation.

Cis-eQTL analysis and functional validation of candidate susceptibility genes for high-grade serous ovarian cancer

Genome-wide association studies have reported 11 regions conferring risk of high-grade serous epithelial ovarian cancer (HGSOC). Expression quantitative trait locus (eQTL) analyses can identify candidate susceptibility genes at risk loci. Here we evaluate cis-eQTL associations at 47 regions associated with HGSOC risk (P≤10(-5)). For three cis-eQTL associations (P<1.4 × 10(-3), FDR<0.05) at 1p36 (CDC42), 1p34 (CDCA8) and 2q31 (HOXD9), we evaluate the functional role of each candidate by perturbing expression of each gene in HGSOC precursor cells. Overexpression of HOXD9 increases anchorage-independent growth, shortens population-doubling time and reduces contact inhibition. Chromosome conformation capture identifies an interaction between rs2857532 and the HOXD9 promoter, suggesting this SNP is a leading causal variant. Transcriptomic profiling after HOXD9 overexpression reveals enrichment of HGSOC risk variants within HOXD9 target genes (P=6 × 10(-10) for risk variants (P<10(-4)) within 10 kb of a HOXD9 target gene in ovarian cells), suggesting a broader role for this network in genetic susceptibility to HGSOC.

Common Genetic Variation in Circadian Rhythm Genes and Risk of Epithelial Ovarian Cancer (EOC)

Disruption in circadian gene expression, whether due to genetic variation or environmental factors (e.g., light at night, shiftwork), is associated with increased incidence of breast, prostate, gastrointestinal and hematologic cancers and gliomas. Circadian genes are highly expressed in the ovaries where they regulate ovulation; circadian disruption is associated with several ovarian cancer risk factors (e.g., endometriosis). However, no studies have examined variation in germline circadian genes as predictors of ovarian cancer risk and invasiveness. The goal of the current study was to examine single nucleotide polymorphisms (SNPs) in circadian genes BMAL1, CRY2, CSNK1E, NPAS2, PER3, REV1 and TIMELESS and downstream transcription factors KLF10 and SENP3 as predictors of risk of epithelial ovarian cancer (EOC) and histopathologic subtypes. The study included a test set of 3,761 EOC cases and 2,722 controls and a validation set of 44,308 samples including 18,174 (10,316 serous) cases and 26,134 controls from 43 studies participating in the Ovarian Cancer Association Consortium (OCAC). Analysis of genotype data from 36 genotyped SNPs and 4600 imputed SNPs indicated that the most significant association was rs117104877 in BMAL1 (OR = 0.79, 95% CI = 0.68-0.90, p = 5.59 × 10-4]. Functional analysis revealed a significant down regulation of BMAL1 expression following cMYC overexpression and increasing transformation in ovarian surface epithelial (OSE) cells as well as alternative splicing of BMAL1 exons in ovarian and granulosa cells. These results suggest that variation in circadian genes, and specifically BMAL1, may be associated with risk of ovarian cancer, likely through disruption of hormonal pathways.

Abstract POSTER-CTRL-1212: The impact of social isolation on ovarian cancer risk and survival

Introduction: In ovarian cancer mouse models, social isolation has been associated with increased circulating markers of angiogenesis, cell migration, and impaired immune response, as well as increasing tumor burden and aggressiveness. In ovarian cancer patients, social isolation has been associated with increased circulating levels of inflammatory and pro-angiogenic factors. However, social isolation has not been investigated in relation to ovarian cancer risk or survival in humans; we addressed these questions in the Nurses’ Health Study (NHS), a longitudinal cohort of 121,701 US-based nurses.

Methods: The Berkman-Syme social network index (BSSNI), a validated measure of social isolation, was assessed every four years in the NHS, starting in 1992. The BSSNI is based on marital status, close friends and relatives, as well as attendance at religious services and other group activities. Women were categorized into four groups: socially isolated, moderately isolated, moderately integrated, and socially integrated. We assessed risk of ovarian cancer associated with the BSSNI and its component parts using Cox proportional hazards models, adjusted for age, duration of oral contraceptive use, family history of ovarian cancer, parity, menopause status, duration of menopausal hormone therapy (by type), and tubal ligation. We further investigated whether the timing of social isolation impacted the results, by evaluating social isolation measured 0-4, 4-8, and 8-12 years prior to cancer diagnosis. In addition, we used Cox proportional hazards models to evaluate whether pre-diagnosis social isolation affected ovarian cancer survival, adjusting as described above plus stage and histology.

Results: In follow-up from 1992-2010, we identified 494 epithelial ovarian cancer cases among 53,839 women who completed the BSSNI. In our main analysis, socially isolated women had no increased ovarian cancer risk compared to socially integrated women (relative risk [RR]: 0.93; 95% confidence interval [CI]: 0.65-1.34), although case numbers were small (N=38). However, moderate isolation was associated with increased ovarian cancer risk (RR: 1.27; 95% CI: 1.00-1.61). When we assessed the components of the BSSNI, widowed women were at increased ovarian cancer risk (RR: 1.40; 95% CI: 1.12-1.75) compared to married women; none of the other BSSNI components were associated with ovarian cancer risk. In the analysis evaluating the role of timing of isolation, socially isolated women in the 8-12 years prior to diagnosis had increased ovarian cancer risk compared to socially integrated women (RR: 1.54; 95% CI: 1.02-2.33). Among the 494 ovarian cancer cases in this analysis, 313 women died due to ovarian cancer during follow-up. Neither the BSSNI nor its components were statistically significantly associated with ovarian cancer-specific survival; however, several of the associations were suggestive. For example, social isolation was not associated with survival (RR: 1.13; 95% CI: 0.41-3.13), but moderate isolation was suggestively associated (RR: 1.61; 95% CI: 0.87-3.00). Additionally, being widowed was associated with a 71% increased risk of ovarian cancer death (95% CI: 0.99-2.96).

Conclusion: These data add to a growing body of evidence that psychosocial stress is important for ovarian cancer risk and progression. Our data suggest that the timing of social isolation is key, which may have implications for the biology of stress. Future studies should confirm these results and evaluate additional sources of psychosocial stress.

Citation Format: Elizabeth M. Poole, Laura Kubzansky, Olivia I. Okereke, Shelley S. Tworoger. The impact of social isolation on ovarian cancer risk and survival [abstract]. In: Proceedings of the 10th Biennial Ovarian Cancer Research Symposium; Sep 8-9, 2014; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(16 Suppl):Abstract nr POSTER-CTRL-1212.

Abstract AS10: Ovarian cancer risk factor associations by tumor aggressiveness in the ovarian cancer cohort consortium (OC3)

Introduction: Ovarian cancer is a heterogeneous disease with about half of patients dying within 3 years, but a third surviving at least 10 years, potentially reflecting differences not only for stage, but also in tumor biology. We evaluated if known and putative ovarian cancer risk factors were differentially associated with tumor aggressiveness, defined as rapidly fatal (death within 3 years) and less aggressive (all others). We assessed oral contraceptive (OC) use, parity, tubal ligation, height, body mass index (BMI), family history of breast or ovarian cancer, age at menarche and menopause, and smoking using pooled data from 18 prospective cohort studies.

Methods: Ovarian cancer characteristics and diagnosis dates were abstracted from pathology reports or cancer registries; registries were used to ascertain vital status and date of death. We used competing risks Cox proportional hazards models to compute relative risks (RR) and 95% confidence intervals (CI) by tumor aggressiveness, stratified on study, age, and birth year, and adjusted for parity and OC use; p-heterogeneity (p-het) was evaluated by likelihood ratio tests.

Results: Among 3,811 cases with known vital status and the potential for at least 3 years of post-diagnosis follow-up, 1,897 (49.8%; median survival=1yr) were rapidly fatal and 1,914 (50.2%; median survival=18yr) were less aggressive. 66% of rapidly fatal and 55% of less aggressive cases were of serous histology. Stronger inverse associations were observed for less aggressive than for rapidly fatal disease for tubal ligation (RR, yes vs. no=0.67 vs. 1.06, respectively; p-het=0.004), parity (RR, per child=0.87 vs. 0.93; p-het=0.001) pack years of smoking (RR, &gt;30 pack-years vs. never=0.78 vs. 1.14; p-het=0.01), and suggestively for family history of breast cancer (RR, yes vs. no=1.15 vs. 0.99, p-het=0.18). Conversely, women with a BMI&gt;30 vs. &gt;22-25 kg/m2 were at higher risk of rapidly fatal disease (RR=1.40), but not less aggressive disease (RR=1.00; p-het=0.04). Associations for other risk factors did not differ by aggressiveness.

Discussion: In this prospective analysis, we observed differential associations by tumor aggressiveness for some risk factors. The potentially stronger association of a family history of breast cancer with less aggressive disease is supported by reports of better survival in BRCA mutation carriers. Associations of parity, tubal ligation, and smoking with less aggressive disease may reflect differential associations by histology; additional analyses will account for histology and stage. The BMI association with rapidly fatal disease suggests that metabolic dysfunction may play a role in tumor aggressiveness. Our results support that pre-diagnostic factors may influence ovarian cancer development and aggressivness. Ultimately, understanding a woman's risk profile with respect to risk of rapidly fatal versus less aggressive disease at diagnosis may aid in determining the most optimal treatment strategy for long term survival.

Citation Format: Shelley S. Tworoger, Elizabeth M. Poole, Alan A. Arslan, Lesley M. Butler, Victoria Kirsh, James V. Lacey, Jr., I-Min Lee, Alpa V. Patel, Kim Robien, Thomas Rohan, Dale P. Sandler, Leo J. Schouten, V. Wendy Setiawan, Kala Visvanathan, Elisabete Weiderpass, Emily White, Nicolas Wentzensen, for the OC3. Ovarian cancer risk factor associations by tumor aggressiveness in the ovarian cancer cohort consortium (OC3) [abstract]. In: Proceedings of the 10th Biennial Ovarian Cancer Research Symposium; Sep 8-9, 2014; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(16 Suppl):Abstract nr AS10.

Abstract POSTER-CTRL-1201: Periodontal bone loss and risk of epithelial ovarian cancer in nurses’ health study

Introduction: Epidemiologic and biomarker studies suggest that inflammation is associated with ovarian cancer. Periodontal disease is an inflammatory response to microbial biofilms in dental plaque, affecting 30-35% of adult US population and potentially leading to loss of periodontal bone tissue and teeth loss. It is associated with several inflammation-related diseases, including cardiovascular disease, lung cancer, and pancreatic cancer. In this study we investigated the association between periodontal bone loss, a marker for advanced periodontal disease, and risk of epithelial ovarian cancer, in the Nurses’ Health Study, a prospective cohort of US-based nurses.

Methods: Periodontal bone loss was self-reported by participants in 1998 and updated in 2000. This analysis included women with baseline information on periodontal bone loss, with no previous history of bilateral oophorectomy, pelvic radiation, or cancer (except non-melanoma skin cancer). Detailed information on relevant lifestyle and reproductive factors was updated every two years and participants were followed for incident ovarian epithelial cancer cases until June 2010. Relative risks (RR) and 95% confidence intervals (CI) for the association of periodontal bone loss with risk of ovarian cancer were assessed using Cox proportional hazards models adjusted for age and other potential confounders, listed below.

Results: During follow-up (1998-2010), 352 incident epithelial ovarian cancer cases were identified among the 55,554 women who provided information on periodontal bone loss in 1998. In the main analysis, adjusted for age, duration of oral contraceptive use, tubal ligation, parity and family history of ovarian or breast cancer, periodontal disease was associated with a suggestively decreased risk of ovarian cancer (RR: 0.83; 95% CI: 0.61-1.13). While there was no association (RR=1.51, 95% CI: 0.82-2.81) between periodontal bone loss and non-serous ovarian cancer, participants with periodontal bone loss were at significantly lower risk of serous ovarian cancer than those with no bone loss (RR=0.64, 95% CI: 0.43-0.98). We observed no evidence of confounding by duration and type of menopausal hormone therapy, regularity of menstrual periods, diet quality (as measured by the alternative healthy eating index), physical activity, body mass index (BMI), diabetes, vitamin D status, NSAID use, smoking, or intakes of caffeine, alcohol, or lactose. The association was similar when stratifying by smoking, history of diabetes, use of hormone therapy, or BMI. History of periodontal bone loss was inversely associated with risk of ovarian cancer in women younger than 68 (median age; RR: 0.61, 95% CI: 0.36-1.00), but not in older women (RR: 1.09, 95% CI: 0.74-1.62)(P-heterogeneity = 0.08).

Conclusions: This is the first study to investigate the association between ovarian cancer and periodontal health. We observed that women with history of advanced periodontal disease, as reflected by periodontal bone loss, may be at decreased risk of serous ovarian cancer, particularly for younger women. Future studies should confirm these findings and investigate the underlying mechanism.

Citation Format: Ana Babic, Elizabeth M. Poole, Kathryn L. Terry, Shelley S. Tworoger. Periodontal bone loss and risk of epithelial ovarian cancer in nurses’ health study [abstract]. In: Proceedings of the 10th Biennial Ovarian Cancer Research Symposium; Sep 8-9, 2014; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(16 Suppl):Abstract nr POSTER-CTRL-1201.

Abstract LB-180: Metabolomic changes in response to chronic stress in healthy mice

Background: Animal models of ovarian cancer suggest that chronic stress and subsequent prolonged distress can increase tumor aggressiveness. While specific stress hormones, such as norepinephrine, appear to have a direct influence on tumors, chronic stress may cause other metabolic perturbations important for cancer development. Here, we searched for potential metabolic biomarkers associated with chronic stress using preclinical models.

Methods: We induced stress with a daily restraint protocol, and assessed the impact of daily restraint versus control in 19 healthy, female C57 black mice on plasma and ovarian tissue metabolomic profiles. At 12 weeks old, mice were randomly assigned to three weeks of daily restraint (2 hr/day; n = 10) or normal care (n = 9). At the end of the experiment, a necropsy was performed and plasma and ovarian tissues were obtained. Metabolomic profiling was conducted using LC-MS-MS, and resulted in peak information for 248 identified metabolites and over 18,000 unidentified peaks.

Results: For the identified metabolites, a Q-Q plot showed a significant deviation from the expected p-value distribution under the null hypothesis for both plasma and tissue when comparing stressed versus non-stressed animals. Triacylglycerols (TAGs), as a group, differed between stressed versus non-stressed animals in both ovary and plasma, although the specific TAGs that were altered and the direction of association appeared to differ by tissue type. Putrescine was significantly higher in stressed versus non-stressed animals in both plasma and tissue. Further, multiple phosphatidylcholines (PCs) and their downstream metabolites, lyso-PCs, differed in plasma of stressed versus non-stressed animals. When considering metabolites that significantly differed in plasma between conditions (FDR&lt;5%), stressed and non-stressed animals clustered together with the exception of one non-stressed animal that clustered with the stressed animals. Similar results were observed for tissue, with 2 stressed and 1-non-stressed animals clustering with the other group. The median correlation between tissue and plasma metabolites was -0.01 for stressed animals and 0.21 for control animals.

Conclusions: Our results suggest that lipid metabolism, which is often dysregulated in cancer cells, may be altered by exposure to stress in healthy animals. Putrescine, which is created by the breakdown of amino acids and is important for cell proliferation, was increased by stress. Overall, our results suggest that chronic stress can lead to metabolic changes at a macro (plasma) and tissue specific level. Additional analyses will characterize specific metabolites altered by stress, detail relationships between tissue and plasma metabolites, and assess correlations with corticosterone.

Citation Format: Shelley S. Tworoger, Elizabeth M. Poole, Guillermo Armaiz Pena, Laura Kubzansky, Susan E. Hankinson, Anil K. Sood, Chirag Patel, Clary Clish. Metabolomic changes in response to chronic stress in healthy mice. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-180. doi:10.1158/1538-7445.AM2015-LB-180

Abstract 858: Periodontal bone loss and risk of epithelial ovarian cancer in the Nurses’ Health Study

Periodontitis, a chronic inflammatory reaction to dysbiotic oral microbiota, is common in the adult population in the United States. It is associated with increased risk of several medical conditions, including cardiovascular diseases, and potentially with lung, oral and pancreatic cancer. One of the proposed mechanisms behind these associations is systemic inflammation, which has also been implied in ovarian cancer etiology. We investigated association between periodontal bone loss, a marker of periodontitis, and risk of epithelial ovarian cancer among 60,560 participants of the Nurses’ Health Study. We did not observe an increased risk of ovarian cancer among participants suffering from periodontal bone loss (HR = 0.86, 95% CI: 0.64-1.15). Association was unchanged after adjusting for numerous factors including smoking. Among women younger than 69 years periodontal bone loss was associated with a 40% (HR = 0.60, 95% CI: 0.36-0.98) decreased ovarian cancer risk, while there was no association in those older than 69 (HR = 1.09, 95% CI: 0.75-1.58), although this difference did not reach a statistical significance (p-heterogeneity = 0.06). There also was a suggestive decreased risk for serous tumors (HR = 0.76, 95% CI: 0.53-1.09). The number of natural teeth and number of root canals, which are other metrics of oral health, were not associated with ovarian cancer risk. Our results do not support an increased risk of ovarian cancer for women with periodontal bone loss; however, given the unexpected associations in younger women, further research is warranted.

Note: This abstract was not presented at the meeting.

Citation Format: Ana Babic, Elizabeth M. Poole, Kathryn L. Terry, Daniel W. Cramer, Ricardo P. Teles, Shelley S. Tworoger. Periodontal bone loss and risk of epithelial ovarian cancer in the Nurses’ Health Study. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 858. doi:10.1158/1538-7445.AM2015-858

Endometriosis: a high-risk population for major chronic diseases?

BACKGROUND

Despite an estimated prevalence of 10% in women, the etiology of endometriosis remains poorly understood. Over recent decades, endometriosis has been associated with risk of several chronic diseases, such as cancer, autoimmune diseases, asthma/atopic diseases and cardiovascular diseases. A deeper understanding of these associations is needed as they may provide new leads into the causes or consequences of endometriosis. This review summarizes the available epidemiological findings on the associations between endometriosis and other chronic diseases and discusses hypotheses for underlying mechanisms, potential sources of bias and methodological complexities.

METHODS

We performed a comprehensive search of the PubMed/Medline and ISI Web of Knowledge databases for all studies reporting on the associations between endometriosis and other diseases published in English through to May 2014, using numerous search terms. We additionally examined the reference lists of all identified papers to capture any additional articles that were not identified through computer searches.

RESULTS

We identified 21 studies on the associations between endometriosis and ovarian cancer, 14 for breast cancer, 8 for endometrial cancer, 4 for cervical cancer, 12 for cutaneous melanoma and 3 for non-Hodgkin's lymphoma, as well as 9 on the links between endometriosis and autoimmune diseases, 6 on the links with asthma and atopic diseases, and 4 on the links with cardiovascular diseases. Endometriosis patients were reported to be at higher risk of ovarian and breast cancers, cutaneous melanoma, asthma, and some autoimmune, cardiovascular and atopic diseases, and at decreased risk of cervical cancer.

CONCLUSIONS

Increasing evidence suggests that endometriosis patients are at higher risk of several chronic diseases. Although the underlying mechanisms are not yet understood, the available data to date suggest that endometriosis is not harmless with respects to women's long-term health. If these relationships are confirmed, these findings may have important implications in screening practices and in the management and care of endometriosis patients.

Folate-mediated one-carbon metabolism genes and interactions with nutritional factors on colorectal cancer risk: Women's Health Initiative Observational Study

BACKGROUND

Investigations of folate-mediated one-carbon metabolism (FOCM) genes and gene-nutrient interactions with respect to colorectal cancer (CRC) risk are limited to candidate polymorphisms and dietary folate. This study comprehensively investigated associations between genetic variants in FOCM and CRC risk and whether the FOCM nutrient status modified these associations.

METHODS

Two hundred eighty-eight candidate and tagging single-nucleotide polymorphisms (SNPs) in 30 FOCM genes were genotyped for 821 incident CRC case-control matched pairs in the Women's Health Initiative Observational Study cohort. FOCM biomarkers (red blood cell [RBC] folate, plasma folate, pyridoxal-5'-phosphate [PLP], vitamin B12, and homocysteine) and self-reported alcohol consumption were measured at the baseline. Conditional logistic regression was implemented; effect modification was examined on the basis of known enzyme-nutrient relations.

RESULTS

Statistically significant associations were observed between CRC risk and functionally defined candidate SNPs of methylenetetrahydrofolate dehydrogenase 1 (MTHFD1; K134R), 5-methyltetrahydrofolate-homocysteine methyltransferase reductase (MTRR; P450R), and PR domain containing 2 with ZNF domain (PRDM2; S450N) and a literature candidate SNP of thymidylate synthase (TYMS; g.676789A>T; nominal P < .05). In addition, suggestive associations were noted for tagging SNPs in cystathionine-β-synthase (CBS), dihydrofolate reductase (DHFR), DNA (cytosine-5-)-methyltransferase 3β (DNMT3B), methionine adenosyltransferase I α (MAT1A), MTHFD1, and MTRR (nominal P < .05; adjusted P, not significant). Significant interactions between nutrient biomarkers and candidate polymorphisms were observed for 1) plasma/RBC folate and folate hydrolase 1 (FOLH1), paraoxonase 1 (PON1), transcobalamin II (TCN2), DNMT1, and DNMT3B; 2) plasma PLP and TYMS TS3; 3) plasma B12 and betaine-homocysteine S-methyltransferase 2 (BHMT2); and 4) homocysteine and methylenetetrahydrofolate reductase (MTHFR) and alanyl-transfer RNA synthetase (AARS).

CONCLUSIONS

Genetic variants in FOCM genes are associated with CRC risk among postmenopausal women. FOCM nutrients continue to emerge as effect modifiers of genetic influences on CRC risk.

Common Genetic Variation In Cellular Transport Genes and Epithelial Ovarian Cancer (EOC) Risk

BACKGROUND

Defective cellular transport processes can lead to aberrant accumulation of trace elements, iron, small molecules and hormones in the cell, which in turn may promote the formation of reactive oxygen species, promoting DNA damage and aberrant expression of key regulatory cancer genes. As DNA damage and uncontrolled proliferation are hallmarks of cancer, including epithelial ovarian cancer (EOC), we hypothesized that inherited variation in the cellular transport genes contributes to EOC risk.

METHODS

In total, DNA samples were obtained from 14,525 case subjects with invasive EOC and from 23,447 controls from 43 sites in the Ovarian Cancer Association Consortium (OCAC). Two hundred seventy nine SNPs, representing 131 genes, were genotyped using an Illumina Infinium iSelect BeadChip as part of the Collaborative Oncological Gene-environment Study (COGS). SNP analyses were conducted using unconditional logistic regression under a log-additive model, and the FDR q<0.2 was applied to adjust for multiple comparisons.

RESULTS

The most significant evidence of an association for all invasive cancers combined and for the serous subtype was observed for SNP rs17216603 in the iron transporter gene HEPH (invasive: OR = 0.85, P = 0.00026; serous: OR = 0.81, P = 0.00020); this SNP was also associated with the borderline/low malignant potential (LMP) tumors (P = 0.021). Other genes significantly associated with EOC histological subtypes (p<0.05) included the UGT1A (endometrioid), SLC25A45 (mucinous), SLC39A11 (low malignant potential), and SERPINA7 (clear cell carcinoma). In addition, 1785 SNPs in six genes (HEPH, MGST1, SERPINA, SLC25A45, SLC39A11 and UGT1A) were imputed from the 1000 Genomes Project and examined for association with INV EOC in white-European subjects. The most significant imputed SNP was rs117729793 in SLC39A11 (per allele, OR = 2.55, 95% CI = 1.5-4.35, p = 5.66x10-4).

CONCLUSION

These results, generated on a large cohort of women, revealed associations between inherited cellular transport gene variants and risk of EOC histologic subtypes.

Proceedings of the second international molecular pathological epidemiology (MPE) meeting

Disease classification system increasingly incorporates information on pathogenic mechanisms to predict clinical outcomes and response to therapy and intervention. Technological advancements to interrogate omics (genomics, epigenomics, transcriptomics, proteomics, metabolomics, metagenomics, interactomics, etc.) provide widely open opportunities in population-based research. Molecular pathological epidemiology (MPE) represents integrative science of molecular pathology and epidemiology. This unified paradigm requires multidisciplinary collaboration between pathology, epidemiology, biostatistics, bioinformatics, and computational biology. Integration of these fields enables better understanding of etiologic heterogeneity, disease continuum, causal inference, and the impact of environment, diet, lifestyle, host factors (including genetics and immunity), and their interactions on disease evolution. Hence, the Second International MPE Meeting was held in Boston in December 2014, with aims to: (1) develop conceptual and practical frameworks; (2) cultivate and expand opportunities; (3) address challenges; and (4) initiate the effort of specifying guidelines for MPE. The meeting mainly consisted of presentations of method developments and recent data in various malignant neoplasms and tumors (breast, prostate, ovarian and colorectal cancers, renal cell carcinoma, lymphoma, and leukemia), followed by open discussion sessions on challenges and future plans. In particular, we recognized need for efforts to further develop statistical methodologies. This meeting provided an unprecedented opportunity for interdisciplinary collaboration, consistent with the purposes of the Big Data to Knowledge, Genetic Associations and Mechanisms in Oncology, and Precision Medicine Initiative of the US National Institute of Health. The MPE meeting series can help advance transdisciplinary population science and optimize training and education systems for twenty-first century medicine and public health.

Periodontal bone loss and risk of epithelial ovarian cancer

PURPOSE

Periodontitis, a chronic inflammatory response to pathogenic bacteria in the oral microbiome, is common among adults. It is associated with several medical conditions, including cardiovascular diseases, and potentially with esophageal, lung, oral, and pancreatic cancer. One of the proposed mechanisms behind these associations is systemic inflammation, which has also been implicated in ovarian cancer etiology. The aim of this study was to evaluate association between ovarian cancer and periodontal bone loss.

METHODS

The association between periodontal bone loss, a marker of periodontitis, and risk of epithelial ovarian cancer was estimated among 60,560 participants of the prospective Nurses' Health Study using Cox proportional hazards analysis. Competing risks analysis was used to estimate association by histologic subtype.

RESULTS

We did not observe an increased risk of ovarian cancer among participants with periodontal bone loss (HR 0.86, 95% CI 0.64-1.15). Among women younger than 69 years, periodontal bone loss was associated with a 40 % (HR 0.60, 95% CI 0.36-0.98) decreased ovarian cancer risk, while there was no association in women older than 69 (HR 1.09, 95% CI 0.75-1.58), although this difference did not reach statistical significance (p-heterogeneity = 0.06). We observed a suggestive decreased risk for serous tumors (HR 0.76, 95% CI 0.53-1.09). The number of natural teeth and root canals, other metrics of oral health, were not associated with ovarian cancer risk.

CONCLUSION

Our results do not support an increased ovarian cancer risk in women with periodontal bone loss; however, there was a significant decrease in risk in women younger than 69. Given the unexpected association between periodontal bone loss and ovarian cancer risk in younger women, further research is warranted.

Evaluating the ovarian cancer gonadotropin hypothesis: a candidate gene study

OBJECTIVE

Ovarian cancer is a hormone-related disease with a strong genetic basis. However, none of its high-penetrance susceptibility genes and GWAS-identified variants to date are known to be involved in hormonal pathways. Given the hypothesized etiologic role of gonadotropins, an assessment of how variability in genes involved in the gonadotropin signaling pathway impacts disease risk is warranted.

METHODS

Genetic data from 41 ovarian cancer study sites were pooled and unconditional logistic regression was used to evaluate whether any of the 2185 SNPs from 11 gonadotropin signaling pathway genes was associated with ovarian cancer risk. A burden test using the admixture likelihood (AML) method was also used to evaluate gene-level associations.

RESULTS

We did not find any genome-wide significant associations between individual SNPs and ovarian cancer risk. However, there was some suggestion of gene-level associations for four gonadotropin signaling pathway genes: INHBB (p=0.045, mucinous), LHCGR (p=0.046, high-grade serous), GNRH (p=0.041, high-grade serous), and FSHB (p=0.036, overall invasive). There was also suggestive evidence for INHA (p=0.060, overall invasive).

CONCLUSIONS

Ovarian cancer studies have limited sample numbers, thus fewer genome-wide susceptibility alleles, with only modest associations, have been identified relative to breast and prostate cancers. We have evaluated the majority of ovarian cancer studies with biological samples, to our knowledge, leaving no opportunity for replication. Using both our understanding of biology and powerful gene-level tests, we have identified four putative ovarian cancer loci near INHBB, LHCGR, GNRH, and FSHB that warrant a second look if larger sample sizes and denser genotype chips become available.

Identification of six new susceptibility loci for invasive epithelial ovarian cancer

Genome-wide association studies (GWAS) have identified 12 epithelial ovarian cancer (EOC) susceptibility alleles. The pattern of association at these loci is consistent in BRCA1 and BRCA2 mutation carriers who are at high risk of EOC. After imputation to 1000 Genomes Project data, we assessed associations of 11 million genetic variants with EOC risk from 15,437 cases unselected for family history and 30,845 controls and from 15,252 BRCA1 mutation carriers and 8,211 BRCA2 mutation carriers (3,096 with ovarian cancer), and we combined the results in a meta-analysis. This new study design yielded increased statistical power, leading to the discovery of six new EOC susceptibility loci. Variants at 1p36 (nearest gene, WNT4), 4q26 (SYNPO2), 9q34.2 (ABO) and 17q11.2 (ATAD5) were associated with EOC risk, and at 1p34.3 (RSPO1) and 6p22.1 (GPX6) variants were specifically associated with the serous EOC subtype, all with P < 5 × 10(-8). Incorporating these variants into risk assessment tools will improve clinical risk predictions for BRCA1 and BRCA2 mutation carriers.