Abstract 914: Xenobiotic metabolizing SNPs and ovarian cancer risk
Authors: White Kristin L. , Sellers Thomas A. , Vierkant Robert A. , Phelan Catherine , Cunningham Julie M. , Schildkraut Joellen M. , Berchuck Andy ,   the Ovarian Cancer Association Consortium, Australian Ovarian Cancer Study Group, Fridley Brooke L. , Olson Janet E. , Beesley Jonathan , Chenevix-Trench Georgia , Goode Ellen L. 
Published: February 2011

Abstract
As the leading cause of mortality among gynecologic cancers, it is critical to increase understanding of ovarian cancer pathogenesis, which remains largely unknown. Several xenobiotic metabolizing enzymes are responsible for processing and inactivating carcinogens that could initiate ovarian carcinogenesis. Here, we hypothesize that single-nucleotide polymorphisms (SNPs) in genes encoding xenobiotic metabolizing enzymes may be associated with differential risk of ovarian cancer. Cases with epithelial ovarian cancer (N=930) and controls (N=1,037), frequency-matched on age and geographic residence, were enrolled at Mayo Clinic and Duke University, and genotyped at 163 tagSNPs in EPHX1, SULT1E1, ADH5, ADH4, ADH6, ADH1A, ADH1B, ADH1C, NQO2, NAT1, NAT2, GSTP1, CYP19A1, CYP1A1, CYP1A2, and NQO1 using an Illumina GoldenGate™ BeadArray array. Logistic regression was used to estimate odds ratios (ORs) and adjust for population structure and other potential confounders, including oral contraceptive use, parity, and family history. SNP-specific statistical analyses identified several noteworthy results including an association with increased risk of ovarian cancer with a SNP (rs2917666) in NAD(P)H dehydrogenase, quinone 1 (NQO1) (per-allele OR 1.16, 95% confidence interval (CI) 1.01-1.33, p=0.04). The SNP rs1051740 in epoxide hydrolase 1, microsomal (xenobiotic) (EPHX1) was suggestive of increased risk of invasive serous disease (TT v CT OR 0.85, 95% CI 0.66-1.09, TT v CC 1.29, 95% CI 0.89-1.88, p=0.09). In an effort to replicate these observations, a subset of 11 SNPs with a p-value &lt; 0.10 were then genotyped in 727 invasive cancer cases and 1,065 controls from an Australian ovarian cancer study using a Sequenom iPlex assay. Results of combined analyses confirmed an association between EPHX1 rs1051740 and increased invasive serous ovarian cancer risk (TT v CT OR 0.99, 95% CI 0.77-1.29, TT v CC OR 1.61, 95% CI 1.23-2.11, p=0.001; recessive OR 1.61, 95% CI 1.25-2.09, p=0.001). This gene is involved in the activation and detoxification of tobacco-derived carcinogens, and smoking has been associated with the mucinous histologic subtype of ovarian cancer. Analyses by histological subtype and gene-environment interaction analyses considering genotype in conjunction with tobacco use and alcohol intake are underway. Due to the important role of EPHX1 in metabolizing pro-carcinogens and the observed association between rs1051740 and risk of invasive serous disease, an examination of this SNP in a larger ovarian cancer consortium is warranted.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 914.