Practice Advisory: Hormonal Contraception and Risk of Breast Cancer Flashcards
This study found that the overall risk of breast cancer among hormonal contraceptive users is low. Because of the low baseline risks in the age groups using hormonal contraception (ie, premenopausal women), the risk difference between hormonal contraception users and nonusers is small. The relationship between oral contraceptive use and breast cancer has been the subject of a number of studies. Meta-analyses of these studies have shown a slight increased risk, ranging from 8–24% (2–4), which is similar to the risk observed in the current study. The increased relative risk observed in the current study translates into 1 additional case of invasive breast cancer for every 7,690 women using hormonal contraception (1). This risk varied with age: for women younger than 35 years, there was 1 additional case of invasive breast cancer for every 50,000 women using hormonal contraception (1).
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The relationship between progestin-only contraceptives and breast cancer risk warrants further study. The risks for different progestin-only formulations were inconsistent and dose-response and duration-response relationships were not present, making it very difficult to interpret these findings. In this study, the LNG-IUD had a relative risk of breast cancer similar to that of combined hormonal oral contraception, whereas contraceptive implants and injectables had no observed increased risk. Methods with higher systemic levels of progestin, particularly injectables, did not seem to be associated with increased risk. The LNG-IUD had increased risk, but this risk was unchanged with duration of use.
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Hormonal contraception has other significant health benefits. The small increased risk of breast cancer identified in this study needs to be interpreted in the context of the benefits of hormonal contraceptive use. The noncontraceptive benefits of hormonal contraception are well-established and include decreased risk of ovarian, endometrial, and colon cancer (4). Because of protection against these cancers, overall cancer risk may be slightly lower in hormonal contraceptive users compared with nonusers, even with the small increased breast cancer risk observed in this study (5). The benefits of hormonal contraceptives in preventing pregnancy are also important. In 2015, the maternal mortality rate in the United States was 26.4 deaths per 100,000 women (6), which is double the risk of developing invasive breast cancer (13 additional breast cancers per 100,000 users) found among women in the current study who used hormonal contraception (1).
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This recent study showed that women who use hormonal birth control methods may have a small increased risk of breast cancer, but the overall risk of breast cancer in hormonal birth control users remains very low.
Hormonal birth control is very effective in preventing pregnancy and may lower a women’s overall risk of cancer by providing protection against other types of cancer.
There are nonhormonal methods of birth control that are also good options.
Women can do things to help lower their risk of breast cancer, like breastfeeding, getting more exercise, and limiting alcohol intake.
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