Do Oral Contraceptives Reduce the Risk of Ovarian Cancer?
Posted: Tuesday, October 16, 2018
A prospective nationwide cohort study among women of reproductive age in Denmark, published in The BMJ, suggests that contemporary combined hormonal contraceptives may reduce the risk of ovarian cancer. Lisa Iversen, MSc, PhD, of the University of Aberdeen, United Kingdom, and colleagues conclude that although a causal effect was not determined, these results are similar to patterns seen in previous research of older forms of progestogen-based contraceptives. In the study population, they found, the use of hormonal contraceptives “prevented 21% of ovarian cancers.”
The study analyzed more than 1.8 million women, aged 15 to 49 years, from a Danish database. Women were excluded if they had cancer, thrombosis, or were treated for infertility before enrollment. The women were placed into the following categories: never-users (no record of being dispensed hormonal contraception), current or recent users (up to 1 year after stopping use), or former users (more than 1 year after stopping use) of different hormonal contraceptives.
During the study period, 1,249 women were diagnosed with ovarian cancer over more than 21.4 million person years. During 13.3 million person years of follow-up, 478 ovarian cancers were reported among ever-users of hormonal contraception. The authors identified 771 cases over 8.1 million person years among women who had never used hormonal contraceptives.
After the investigators accounted for a number of factors, women who used hormonal contraception at any point had a 34% lower risk of developing ovarian cancer than did those who had never used contraceptives. The reduction was greater among women who were current or recent users of contraceptives and especially among those who took the combined pill compared with those who used progestogen-only methods. The benefits seemed to diminish among those who had not used the pill for at least 1 year.