Depo-Provera Shot Side Effects May Increase Breast Cancer Risk: Study

The Depo-Provera birth control shot may increase the risk of breast cancer, according to the findings of new research. 

In a study published in the medical journal Cancer Research, researchers found that young women who were on Depo-Provera for a year or more were twice as likely as their contemporaries to be diagnosed with breast cancer.

Depo-Provera (depo-medroxyprogesterone acetate), also known as DMPA or the Depo shot, is an injectable form of birth control developed by Pfizer and approved by the FDA in 1992. The shot is given four times a year and prevents ovulation.

Researchers looked at the records of more than 1,000 women from Seattle between the ages of 20 and 44 who had been diagnosed with breast cancer and compared them to more than 900 women who had not been diagnosed with breast cancer. They found that women who used the Depo shot for a year or more were 2.2 times as likely to be diagnosed with invasive breast cancer.

According to the findings, the risk decreased the longer a woman was off the shot. That finding increase the likelihood of a causal link between the depo shot and breast cancer.

Researchers noted that even with the increased risk, the chances of a breast cancer diagnosis in young women is low, and that the risk dissipated after use of the shot was discontinued. They said their findings emphasize the importance of identifying the potential risks associated with specific forms of contraceptives and the need to weigh forms of contraceptives and their risks against the alternatives.