Women who use postmenopausal hormones have an increased risk of developing ovarian cancer, according to a study conducted in Denmark. These results were published in the Journal of the American Medical Association.
Estrogen, with or without progestin, is an effective treatment for many menopausal symptoms. During the last several years, however, studies have raised concerns about the health effects of postmenopausal hormone therapy.
Use of estrogen plus progestin has been linked with an increased risk of heart disease, breast cancer, stroke, and blood clots and a decreased risk of fractures and colorectal cancer. Use of estrogen alone, which is generally reserved for women who have had a hysterectomy, has been linked with an increased risk of strokes and a decreased risk of fractures.
Studies have also suggested a possible increase in ovarian cancer among women who use postmenopausal estrogen. To further evaluate the potential link between ovarian cancer and postmenopausal hormones, researchers in Denmark conducted a study among more than 900,000 women between the ages of 50 and 79.
During an average of eight years of follow-up, there were 3,068 diagnoses of ovarian cancer, 2,681 of which involved epithelial ovarian cancer (the most common type of ovarian cancer).
Compared with women who had never used hormone therapy, current users of hormones were 38% more likely to develop any ovarian cancer and 44% more likely to develop epithelial ovarian cancer.
Risk was greatest among current users of hormones and declined with years since last use.
Risk was increased among users of estrogen alone as well as among users of estrogen plus progestin. Risk did not vary by duration of use.
The researchers estimate that hormone use results in one extra case of ovarian cancer for every 8,300 women taking hormone therapy each year.
These results provide additional evidence that use of postmenopausal hormones increases the risk of ovarian cancer.
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 Steinrud Mørch L, Løkkegaard E, Halm Andreasen A, Krüger-Kjær S, Kidegaard Ø. Hormone therapy and ovarian cancer. Journal of the American Medical Association. 2009;302: 298-305.