Cancer Research Lab

Data from a study involving almost 40,000 women support a potential role of oral contraceptives in reducing the risk of colorectal cancer, researchers report in the April issue of the American Journal of Epidemiology.

As lead investigator Dr. Jennifer Lin said, “Our study suggests that exogenous hormone use such as oral contraceptives may confer some protection among women against colorectal cancer development.”

Dr. Lin of Harvard Medical School, Boston and colleagues evaluated associations of oral contraceptive use and reproductive factors and risk of colorectal cancer among 39,680 participants in the Women’s Health Study.

During an average of 11 years of follow-up there were 267 incident cases of colorectal cancer. Ever having used of oral contraceptives was associated with a lower risk of colorectal cancer (relative risk, 0.67).

For OC use from 6 months to less than 3 years, the relative risk was 0.61 There was little further decrease in risk with longer duration of use.

However, despite the apparent relationship with oral contraceptives, concluded Dr. Lin, “The association between endogenous production of sex hormones — reproductive factors — and colorectal cancer incidence remains unclear.”