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Does taking the birth control pill increase the risk of breast cancer?

Hormonal birth control or “the pill” has been used for more than half a century to help prevent pregnancy and help couples plan when they want to have children. It is also highly effective in treating painful, heavy or irregular bleeding and is therefore prescribed frequently for problems associated with menstrual cycles. Hormonal contraception prevents ovarian, uterine and colon cancers and osteoporosis in women.

Like all medications and over-the-counter supplements, there are potential adverse effects. The most serious side effects of using hormones are experiencing a blood clot, a slight increase risk of liver cancer or a possible increase in breast cancer risk. Shared decision making between individual women and the provider as to the benefits and risks and expected outcomes regarding hormonal contraception should be addressed at the initiation of therapy, regardless of whether it is being used for pregnancy prevention or cycle control.

Does taking the birth control pill increase the risk of breast cancer?

The short answer is…..maybe. However, the overall risk of cancer remains very low and hormonal contraception decreases the risk of other types of cancers (uterine, ovarian and colon).

A recently published study in the New England Journal of Medicine (December 2017) may link hormonal contraception to breast cancer.  It is a large study that spanned over more than a decade comparing women in Denmark who used hormonal contraception (the pill, mini-pill, patch, NuvaRing, and progestin-containing IUD) and the risk of acquiring breast cancer compared to women who did not use hormonal contraception. The take-home points of this retrospective, observational trial are:

  1. Women who use hormonal birth control methods may have a small increased risk of breast cancer, but the overall risk remains very low. This is similar to findings in several other studies.  This means that one more woman out of every 7,690 hormone users will develop breast cancer.  For women younger than age 35, this risk is much less; one more woman per 50,000.
  1. The overall risk of cancer may be slightly lower in hormonal contraceptive users because hormones decrease the risk of ovarian, uterine (endometrial) and colon cancers.
  1. Further investigation of progestin-only formulations (the shot, mini pill or certain IUDs) is necessary. It was difficult to systematically analyze the data because of the various dose and duration of the hormones used in the Danish study.
  1. The risk of death during pregnancy is twice as high as the risk of developing breast cancer because of hormonal contraception. In 2015, about 26 out of 100,000 women died during pregnancy. There were 13 more women out of 100,000 who developed breast cancer in the hormone group compared to those who didn’t use hormonal contraception.
  1. The quality of the study should be considered when evaluating any type of research. Randomized controlled trials (RCT) are considered the “gold standard” because they follow the most scientifically rigorous method of testing a theory.  Cost, logistics and ethical considerations need to be considered when doing research and may make it impossible to design an RCT. The Danish study was a retrospective, observational trial whichmeans the data, conclusions, and generalizations to larger populations may require further investigation.

Some limitations of the Danish trial specifically that may affect the interpretation of the results include:  not accounting for breastfeeding history, alcohol consumption or physical activity.  The participants were from a northern European population, hence findings may or may not be generalized to other populations of women.

  1. Many factors are associated with the risk of developing breast cancer. Modifiable risk factors should be addressed by every  Risk factors for developing breast cancer include:

sex & race
family & personal history
pregnancy & breastfeeding history
menstrual history & hormone replacement therapy
decreased physical activity
alcohol & smoking
dense breast tissue

  1. Self-breast awareness, clinical breast examinations, and screening mammograms are essential in detecting breast cancer early so effective treatment can be initiated.

Hormonal contraception for many women is the safest and effective way of preventing pregnancy and regulating hormones when this is necessary.  Other non-hormonal methods of contraception are available for those who are concerned about the risk.  A discussion regarding current and accurate information on the effectiveness of hormones, the expected outcome, and individual risk will help women make the best decision for them.

Haley Pledger, PA
Women’s Care
Matthew Walton, DO
Austin Bills, DO
Family Medicine
Aaron Fausett, PA
Family Medicine
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