Tomas Riman, M.D., of Falu Hospital and Karolinska Institute in Sweden, and his coworkers report that the use of both estrogens and estrogens combined with a sequential, or cyclic, regimen of progestins was associated with an increased risk of epithelial ovarian cancer. However, use of estrogens combined with a continuous, or daily, regimen of progestin was not associated with increased ovarian cancer risk.
Estrogen replacement therapy, which helps relieve symptoms of menopause and may prevent osteoporosis and heart disease, has been associated with an increased risk of uterine cancer. In women with an intact uterus, combining estrogens with progestins has been shown to reduce this risk.
Results of epidemiologic studies looking at estrogen replacement therapy and the risk of ovarian cancer have not been as clear. The authors point out that most studies that examined hormone replacement therapy and ovarian cancer did so without indicating whether estrogens were taken alone or supplemented with progestins.
In the new study, Riman and his coworkers identified 655 women with epithelial ovarian cancer from Swedish cancer registries, along with 3,899 cancer-free women. The women, who were between the ages of 50 and 74, completed questionnaires about their history of HRT use and other factors that may have affected their risk of ovarian cancer.
The authors found that women who had used estrogens alone had a 43% increased risk of developing epithelial ovarian cancer compared with women who had never used such therapy. However, this risk increase was seen only in women with an intact uterus. Women who had undergone hysterectomies and had used estrogens were not at increased
Contact: Linda Wang
Journal of the National Cancer Institute