Abstract A52: Oral contraceptive use and risk of colorectal polyps in a colonoscopy based study in western Washington state

Abstract

Abstract Background: Most colorectal cancers arise from polyp precursor lesions, including advanced adenomas and a subset of serrated polyps, termed sessile serrated polyps. Growing literature on oral contraceptives (OC) use and risk of colorectal cancer suggests an inverse association. However, very little is known about the role of OC in the development of colorectal polyps. We investigated the relationship between OC use and the risk of subsets of colorectal polyps in a colonoscopy based study in western Washington State. Methods: Study participants were 20-79 year-old women enrollees at Group Health, an integrated health care system in Seattle, Washington who underwent a colonscopy for any indication from 1998-2007. Study eligible participants completed a structured interview to collect risk factor information, including reproductive history and exogenous hormone use. OC use was categorized according to ever use, recency of use, and duration of use. Participants were diagnosed as having adenomas (n=298), serrated polyps (n=336), both types of polyps (n= 105) or as polyp-free controls (n=615) on the basis of a standardized pathology review. Multivariable polytomous logistic regression was used to compare case groups with polyp-free controls and other case groups; odds ratios (OR) and 95% confidence intervals were estimated adjusted for age, race, educational status, body mass index, smoking, alcohol intake, anti-inflammatory drug use, use of postmenopausal hormones, parity and age at first birth. Results: Ever use of OC was not associated with risk for adenomas (adjusted OR 0.82, 95% CI 0.57-1.20) or serrated polyps (adjusted OR 0.93, 95% CI 0.64-1.36) while the risk for synchronous presence of both types of polyps was elevated (adjusted OR 1.43, 95% CI 0.77-2.67) (p=0.39 for the three polyp subtypes). Strength of association did not vary significantly between adenomas and serrated polyps for duration of use (p=0.43) and time since last use (p=0.75). Additionally, the associations did not differ significantly by age, lesion severity (advanced vs. nonadvanced for adenomas, sessile serrated vs. hyperplastic for serrated polyps), or location (right vs left) for either adenomas or serrated polyps. Conclusions: We observed no strong evidence that adenomas or serrated polyps were associated with ever use of OC pills. Although the majority of studies suggest a reversible effect of exogenous postmenopausal hormones on colorectal neoplasia, we did not find any association between time since last use of OC pills and development of either types of polyps. Further larger studies are needed to better understand the mechanistic processes through which oral contraceptives may be associated with the development of adenomas and serrated polyps. Citation Format: Sheetal Hardikar, Andrea N. Burnett-Hartman, Polly A. Newcomb. Oral contraceptive use and risk of colorectal polyps in a colonoscopy based study in western Washington state. [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr A52.