Hormonal Contraception And Breast Cancer: A Matter Of Context

In October 2006, a meta-analysis including 39 studies focused on the impact of combined oral contraceptives (COCs) on premenopausal breast cancer in women under 50. It followed a Collaborative Reanalysis from ten years earlier that involved 53,297 women with breast cancer and 100,239 controls, which found a relative risk (RR) of 1.24 for current COC users and a slightly increased risk for up to 10 years after cessation, but no increased risk after 10 years. The recent meta-analysis by Kahlenborn et al. reported a similar odds ratio (OR) of 1.19 for COC use at any point in life. It also found that COC use before the first full-term pregnancy (PGMT) increased the risk of breast cancer (OR 1.44) compared to after PGMT (OR 1.15). The absolute risk increase was estimated at 8 additional cases per 100,000 former users per year, with a higher risk associated with use before PGMT. The study concluded that there is a slight but significant increase in the risk of premenopausal breast cancer with COC use, but the absolute risk for an individual woman is very low, and the benefits of hormonal contraception must be weighed against potential risks.