Risk of breast, uterine corpus, and ovarian cancer in women receiving medroxyprogesterone injections
A. P. Liang, A. G. Levenson, P. M. Layde, J. D. Shelton, R. A. Hatcher, M. Potts and M. J. Michelson
Animal studies have yielded conflicting results on the carcinogenicity of
long-acting progestins. Since more than 1.5 million women worldwide are
currently receiving injections of a contraceptive progestin, depot
medroxyprogesterone acetate, this is potentially an important public health
problem. We obtained information on the occurrence of breast, uterine, and
ovarian cancer among 5,000 black women attending a metropolitan hospital's
family planning clinic who had received injections of medroxyprogesterone
for contraception (between 1967 and 1976). The women were followed up for
four to 13 years after their initial medroxyprogesterone injection. We
compared the observed number of cancer cases in these women with the
expected number based on annual age-, race-, and sex-specific rates derived
from National Cancer Institute data. During more than 40,000 woman-years of
observation, we found no evidence of an increased risk of developing cancer
of the breast, uterine corpus, or ovary in these women. After adjusting for
possible underascertainment of cancer because of incomplete follow-up, we
found the relative risk for medroxyprogesterone users to be 0.7 for breast
cancer (95% confidence limits, 0.3 to 1.4), 1.2 (95% confidence limits, 0.1
to 6.7) for cancer of the uterine corpus, and 0.8 (95% confidence limits,
0.1 to 4.6) for ovarian cancer.
