A large Danish cohort study found that users of hormonal contraception may have a slightly higher risk of breast cancer. This confirms previous studies finding a small, temporary increase in breast cancer associated with older hormonal contraceptives. Although other studies indicate that hormonal contraceptives lower the risk of ovarian, endometrial, and colorectal cancer, fear of breast cancer has led some patients to discontinue their birth control.
How can we frame this issue so that we communicate honestly without alarming patients? Relative risk may exaggerate people’s perception of a method’s danger. We should describe absolute risk instead, as a proportion using a consistent denominator.
For example, instead of saying, “hormonal contraception raises your risk of breast cancer by 20%,” we should say, “the risk of breast cancer is 55 per 100,000 non-users of hormonal contraception, compared with 68 per 100,000 users.”
Morch, Lina S. Skovlung, Charlotte W. et. al. Contemporary Hormonal Contraception and the Risk of Breast Canter. The New England Journal of Medicine. Dec. 2017, 377; 2228-2239.
Carroll, Aaron E. Birth Control and Breast Cancer: Putting the Risk in Perspective. The New York Times. 10 December 2017, accessed 15 December 2017. https://www.nytimes.com/2017/12/10/upshot/birth-control-breast-cancer-risks.html
Maguire, K. Westhoff, C. The state of hormonal contraception today: established and emerging noncontraceptive health benefits. American Journal of Obstetrics & Gynecology. Oct 2011, S4-8.
Pharma-free: The Reproductive Health Access Project does not accept funding from pharmaceutical companies. We do not promote specific brands of medication or products. The information in the Contraceptive Pearls is unbiased, based on science alone.