Long-term Estrogen Replacement Therapy Could Increase Risk of Ovarian Cancer

Long-term Use of Estrogen Replacement Therapy Could Increase Risk of Ovarian Cancer

Postmenopausal women who have used estrogen replacement therapy (ERT) for more than 10 years could be at an increased risk of dying from ovarian cancer, according to the results of a study recently published in the Journal of the American Medical Association.

Currently, hormone replacement therapy (HRT) is commonly used to relieve the symptoms of menopause. HRT consists of a balanced combination of estrogen and progesterone. ERT, on the other hand, consists of only estrogen, with no other hormone to balance it. ERT was commonly used until the mid-1980s when HRT became available. In the past, researchers have speculated that ERT increases the risk of ovarian cancer, but few studies have documented this risk.

Researchers from the American Cancer Society conducted a study to evaluate the relationship between ERT and subsequent death from ovarian cancer. The researchers analyzed data from 211,581 postmenopausal women from the Cancer Prevention Study II. The women had no history of cancer, hysterectomy, or ovarian cancer at the time of enrollment. The women completed a baseline questionnaire in 1982 and were followed until 1996.

During the 14-year follow-up, 944 women died from ovarian cancer. Women who were using ERT upon enrollment in the study had higher death rates from ovarian cancer than women who had never used ERT. Duration of use appeared to further increase the risk. Women who were using ERT at the beginning of the study who had been using it for 10 or more years were 2.2 times more likely to develop ovarian cancer than women not using ERT. Women who had used ERT for 10 or more years, but quit less than 15 years prior to the beginning of the study were twice as likely to develop ovarian cancer. Those who had used ERT for 10 or more years, but had quit more than 15 years prior to the study were 1.3 times more likely to develop ovarian cancer.

The researchers concluded that postmenopausal women who used ERT for 10 or more years had an increased risk of dying from ovarian cancer that lasted up to 29 years after cessation of use. More research is necessary to further define the relationship between ERT and ovarian cancer, as well as to assess the impact of HRT. While the results of this study suggest that estrogen can increase the risk of ovarian cancer, they do not provide any insight into the risk when estrogen is combined with progesterone, as in HRT. Women who are taking HRT may wish to speak with their physicians about the potential risks and benefits of this therapy; however, often the beneficial effects outweigh the risks. While all women may wish to undergo an annual pelvic exam as screening for ovarian cancer, women who have used ERT for more than 10 years may wish to speak with their physicians about their risk and screening for the disease. (Journal of the American Medical Association, Vol 285, pp. 1460-1465, 2001)

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