A new study has found that young women who use the injectable contraceptive Depo-Provera for a year or more have about double the risk of breast cancer. This drug has been available for over 20 years.
Published in the journal Cancer Research, the case-control study analyzed data on over 1,000 women who had breast cancer, and compared them to over 900 women without the disease. All of the women were between the ages of 20 and 44, and about 3 percent had used Depo-Provera in the past year. Compared to women who had never used the injectable drug, those who used Depo-Provera were 2.2 times more likely to be diagnosed with breast cancer.
According to researchers from the Fred Hutchinson Cancer Research Center who led the study, the results are biologically plausible, in that Depo-Provera is the only U.S. contraceptive that contains the same progestin used in Prempro, an oral hormonal therapy that was also associated with an increased risk of breast cancer in the Women s Health Initiative study. Progestins are a type of hormone used in some contraceptives and some hormone replacement therapies.
But the study s lead author Dr. Christopher Li reiterates that breast cancer among young women is still a rare disease. The absolute risk of breast cancer for women in their 30s is just 1 in 233, according to statistics from the National Cancer Institute a risk that, as ACSH's Dr. Gilbert Ross points out, is very low. So low, in fact, that even if you double this risk, it still shouldn t be cause for alarm. Dr. Ross doesn t think that the latest study results should dissuade young women from using Depo-Provera which is injected only four times a year since it offers a convenient, safe, and inexpensive method of birth control. Instead of requiring women to take a daily pill, Depo-Provera takes a lot of the thought out of birth control. he observes.
However, this study should prompt doctors to discuss the relative risks and benefits of Depo-Provera with women who are using this method, as the increased risk, while small, is not inconsequential. Also, women should remember that such methods of contraception do not protect against sexually transmitted diseases, Dr. Ross says.