Depo-medroxyprogesterone acetate (DMPA) is an injectable contraceptive that contains the same progestin as the menopausal hormone therapy regimen found to increase breast cancer risk among postmenopausal women in the Women's Health Initiative clinical trial. However, few studies have evaluated the relationship between DMPA use and breast cancer risk. Here we conducted a population-based case-control study among 1028 women 20-44 years of age to assess the association between DMPA use and breast cancer risk. Detailed information on DMPA use and other relevant covariates was obtained through structured interviewer administered in-person questionnaires, and unconditional logistic regression was used to evaluate associations between various aspects of DMPA use and breast cancer risk. We found that recent DMPA use for 12 months or longer was associated with a 2.2-fold (95% CI: 1.2-4.2) increased risk of invasive breast cancer. This risk did not vary appreciably by tumor stage, size, hormone receptor expression, or histological subtype. Although breast cancer is rare among young women and the elevated risk of breast cancer associated with DMPA appears to dissipate after discontinuation of use, our findings emphasize the importance of identifying the potential risks associated with specific forms of contraceptives given the number of available alternatives.
- Received December 14, 2011.
- Revision received January 26, 2012.
- Accepted February 15, 2012.
- Copyright © 2012, American Association for Cancer Research.