Oral contraceptives (OC) are associated with a decreased risk of colorectal cancers; however a recent study reported an increased risk of small colorectal adenomas associated with OC use. To determine if these results were replicable in a different study population, we investigated the relationship between OC use and other reproductive factors and risk of colorectal polyps in a case-control study in western Washington.
Study participants were 24–79 year old female enrollees at an integrated health care system in western Washington who were diagnosed as having adenomas (n=299), serrated polyps (n=337), both types of polyps (n= 105) or as polyp-free controls (n=615) through an index colonoscopy and completed a structured interview to collect reproductive history information. Multivariable polytomous logistic regression was used to compare case groups to controls and to each other; odds ratios (OR) and 95% confidence intervals were estimated.
There was no association between OC use, duration of use, or recency of use and the risk of either adenomas or serrated polyps [adjusted OR for OC ever use (95% CI) =0.85(0.58–1.23) and 0.96(0.66–1.40), respectively], and associations did not differ by lesion severity within the adenoma or serrated pathways. Further, no associations were observed between other reproductive factors and risk of colorectal polyp subtypes.