The association of depo-medroxyprogesterone acetate and breast cancer

Abstract

The use of depo-medroxyprogesterone acetate (DMPA) as an injectable contraceptive for women has continued to be controversial for over 10 years. The U.S. Food and Drug Administration has not approved it for contraceptive use but the World Health Organization has. We undertook a case-control study to clarify the possible association of breast cancer and DMPA use. Subjects were selected from women enrolled in the Grady Memorial Hospital Family Planning Clinic in Atlanta, Georgia, from 1967 to 1979. The risk of breast cancer in DMPA users compared to nonusers is identical. The small number of women with breast cancer, the short average exposure to DMPA, and the lack of detail about the subjects themselves caused us to interpret our results cautiously. However, it seems reasonable to conclude that short-term use of DMPA among black women is not associated with any increased risk of breast cancer.

PIP: This case-control study attempted to determine the possible association of breast cancer and depo-medroxyprogesterone acetate (DMPA) injectable contraceptive use. Of 11,400 women who had received the drug, 30 had breast cancer. 29 of these 30 were black women. 70% of cases were aged 30 years or older. Controls were matched for age and parity. Of the women with breast cancer, 16.7% had been exposed to DMPA whereas only 17.9% of controls had been exposed. The risk of breast cancer in DMPA users compared to nonusers was exactly 1. Controlling for parity did not alter this. For all 5 exposed cases, DMPA exposure preceded the diagnosis of the disease by an average of 4 years. The mean number of injections for women with breast cancer and for controls was 2.8 and 3.3, respectively. Hence, though the number of cases was small and the average exposure was short, it is still concluded that short-term use of DMPA among black women is not associated with any increased risk of breast cancer.