Contraception and Hormones
- Hormonal contraceptives (“the Pill”)
- Long-acting reversible contraceptives such as levonorgestrel IUDs or the Nexplanon implant
The two types of hormones that are used in hormonal birth control are:
Does Birth Control Cause Breast Cancer?
Hormonal methods of contraception are more effective than other methods, but concern has been raised about breast cancer risk.
A study recently published in the New England Journal of Medicine looked at the outcomes of 1.8 million Danish women ages 15 to 49, who were followed for an average of more than 10 years. They found that among these women, those who were currently or recently using hormonal birth control had a 20% higher relative risk for the development of breast cancer during the study period.
However, while users of birth control were relatively more likely to develop breast cancer, it is important to understand that overall, their risk of breast cancer was still extremely low, because the risk of developing breast cancer during the reproductive years is very low! For instance, an average 25 year old woman has about a 0.1% risk of developing breast cancer within the next 5 years.
If birth control use increases her risk by 20%, she would now have a 0.12% risk (still much less than 1%). Another way of stating this small increased risk is that for every 7,690 women using hormonal contraception for one year, there would maybe be one extra breast cancer case diagnosed.
Benefits and Risk of Hormonal Birth Control
Of course, when evaluating the risks of birth control, it is important to acknowledge any and all risks as well as their benefits, the foremost of which is preventing unintended pregnancy. Birth control allows women to control their family size without sacrificing the joy of sexual intimacy with a (monogamous) partner. Pregnancy is also not without risk itself – for instance, one in 1,600 women will develop a blood clot during pregnancy or the postpartum period, and one in 5,810 pregnant women in the United States die as a result of pregnancy complications.
Even women who are at an increased risk for breast cancer may still choose hormonal contraceptives. For instance, for many young women who are positive for BRCA 1 or 2 mutations, the 50% reduction in ovarian cancer risk outweighs the small absolute increase in breast cancer risk. Hormonal contraceptives are recommended for this group for ovarian cancer risk reduction.
Hormonal birth control, like any therapy, carries some risk. The major risk is the rare risk of deep vein thrombosis/clot. When making decisions about whether a medication is right for you, it helps to understand the magnitude of the risk. For most women in their reproductive years, the benefits greatly outweigh the risks for most women. All women, especially those who are worried about their personal breast cancer risk, should seek care from providers who are willing and able to help manage their health in accordance with their risk factors, their values and their reproductive goals.
Help reduce your breast cancer risk
- Eat healthy
- Don’t smoke
- Exercise daily
- Breastfeed if you have a baby
- Correct any low vitamin D levels
Be Strong. Be Healthy. Be in Charge!
-Holly Pederson MD and Sarah Hershman MD
- Contraceptive Use in the United States. Guttmacher institute. September 2016.
- Contraception. Centers for Disease Control and Prevention. Accessed January 3, 2018. Page last updated: February 9, 2017.
- March et al. Contemporary Hormonal Contraception and the Risk of Breast Cancer.N Engl J Med 2017; 377:2228-2239 December 7, 2017. DOI: 10.1056/NEJMoa1700732
- Tyrer J, Duffy SW, and Cuzick J. A breast cancer prediction model incorporating familial and personal risk factors. Statistics in Medicine 2004; 23 (7): 1111-1130.
- Pregnancy Mortality Surveillance System. Centers for Disease Control and Prevention. Accessed January 2, 2018. Page last updated November 9, 2017.
Holly J. Pederson, MD is the Director of Medical Breast Services at Cleveland Clinic and an Associate Professor of Medicine at the Cleveland Clinic Lerner College of Medicine of CWRU. Her practice focuses on breast diagnostics, breast cancer risk assessment and management of the high risk patient.
Sarah Hershman, MD is a PGY2 resident in Obstetrics and Gynecology at the Cleveland Clinic. She has an interest in family planning.
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