In November, a study was published in the New England Journal of Medicine, which linked the use of birth control pills and other hormonal birth control to an increased risk of breast cancer.
This study followed 1.8 million Danish women for 11 years and confirmed what we already knew about this association. With newer hormonal contraceptives with lower doses of hormones, the hope was the increased risk of breast cancer was diminished.
This study was important, because we had very little data on current low-dose birth-control pills and IUD’s containing progesterone and its relationship to breast cancer. As gynecologists, we assumed that a lower dose of hormones meant a lower risk of breast cancer.
One can expect an additional 13 cases of breast cancer for every 100,000 women. Another way to say that is for every 7,690 women who use hormonal contraception for one year, one additional women will get breast cancer.
Although the study was helpful, please keep in mind some of its limitations: this was an observational study that followed women over time. The data did not allow for adjusting some known risk factors such as age of first menstruation, whether or not women breast fed, alcohol consumption, and generalized health such as physical activity and diet.
Also note that oral contraceptives have benefits as well: a reduction in ovarian as well as endometrial (uterine) cancer, not to mention other benefits as it relates to menstrual control.
Actually, if we look at all cancers together, the benefits outweigh the risks as far as the development of all cancers.
The best advice: Every women should discuss her particular situation with her doctor. Although there are risks (particularly if you smoke), there are also significant benefits, and for some the benefits will be greater than the harms.
For the full article in the New England Journal of Medicine, click here.