The latest on birth control and breast cancer risk

Earlier this week, a study was released indicating that the use of hormonal forms of contraception can increase a woman’s risk of breast cancer. We asked Stefani Yudasz, NP, who runs the High Risk Breast Clinic, to weigh in on the latest findings and what they mean for you.

Why do these hormones raise breast cancer risk?

The exact science behind this is complex and continually studied. What we do know is that estrogen and progesterone have a proliferative effect on the cells in the breast. This occurs both naturally with our endogenous female hormones, as well as with exogenous hormones (through hormonal contraception or hormone replacement therapy). Proliferation causes increased cell turnover, which allows for an increased opportunity for cells to mutate abnormally and develop atypical or cancerous cells. Additionally, the hormones used in hormonal contraception, estrogen and progestin (synthetic progesterone), can cause increased growth if a breast cancer is already present because the most common type of breast cancer is hormonally sensitive. Tumor cells make receptors for certain tumor markers, two of which are estrogen and progesterone. Cancers that make receptors for these two markers are driven by our female hormones and exogenous estrogen and progestin can feed into an already present breast cancer.

Is it the estrogen or progestin in birth control that raises breast cancer risk?

Both estrogen and progestin used in hormonal contraceptives are associated with an increase in the risk for breast cancer. The recent Danish study also examined progestin-only options, such as the intrauterine device (IUD), which was also shown to increase the risk slightly. However, studies on progestin-only contraception have been mixed thus far, and continued research is needed to evaluate the effects of lower-dose pills, and progestin-only options.

Is a lower level of hormones safer?

The hope, of course, over the last few decades was that a lower dose of hormones in hormonal contraceptives would not incur the same risks as historical contraceptives with much higher doses. This recent study demonstrated that that is unfortunately not the case. However, it is important to note that this is one study, and the study did not take into account other factors that may affect breast cancer risk, such as age at menarche (age at first menstrual cycle), age at first live birth, breastfeeding history, alcohol use, and family history, to name a few.

Are there any pros (aside from family planning) to birth control that outweigh the risk?

Absolutely. Aside from family planning, hormonal contraception comes with other benefits such as a reduction in risk for certain types of cancers including ovarian, uterine and colon cancer. With the significant advances we have seen in breast cancer screening and detection, breast cancer can be caught at earlier stages. Unfortunately, we have no effective screening options for ovarian cancer at this time, so many providers argue that the reduction in risk for ovarian cancer outweighs any slight increase risk for breast cancer. Additionally, the increased risk of breast cancer associated with hormonal contraception does not continue with the woman throughout her lifetime. This risk goes down once the woman stops the contraception, and can even revert back to average risk over time.

What is the big takeaway for women?

The decision to use hormonal methods for contraception is an individual, personal decision. Every woman considering options for contraception should have a conversation with their provider discussing the risks and benefits that are specific to them. Particularly, women with a strong family history of breast cancer and/or other associated factors known to increase the risk of breast cancer, should make a shared decision based upon risks, benefits, goals and quality of life. While we always take results of significant studies into consideration, the recent Danish study demonstrating an increased risk of breast cancer with hormonal contraception will likely not change the perceptions and current recommendations of women's health providers, as this fact has always been taken into account when recommending contraceptive options.


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