According to the results of a study published in the Journal of the National Cancer Institute, long-term use of estrogen alone or estrogen plus progestin appears to increase a woman’s risk of developing ovarian cancer.
As women reach menopause and beyond, more than 80% will experience symptoms such as hot flashes, night sweats, sleep disturbance, and vaginal dryness. Estrogen, with or without progestin, is the most effective treatment for many of these symptoms. Recent studies, however, 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.
To evaluate the effects of postmenopausal hormone therapy on risk of ovarian cancer, researchers evaluated information from the National Institutes of Health-AARP Diet and Health Study Cohort. This study enrolled more than 97,000 women who were between the ages 50 and 71 years at the start of the study.
During follow-up, 214 cases of ovarian cancer were diagnosed among study participants. The frequency of ovarian cancer among women who had used postmenopausal hormone therapy was compared to the frequency of ovarian cancer among women who had not used postmenopausal hormone therapy.
- Use of estrogen alone for fewer than 10 years was not linked with an increased risk of ovarian cancer.
- Use of estrogen alone for 10 years or longer was linked with an 89% increase in risk of ovarian cancer.
- Use of sequential estrogen plus progestin for five or more years was linked with a three-fold increase in risk of ovarian cancer. Sequential therapy was defined as progestin for less than 15 days per cycle.
- Use of continuous estrogen plus progestin for five or more years was linked with an 82% increase in risk of ovarian cancer. Continuous therapy was defined as progestin for 15 or more days per cycle.
The researchers conclude that long-term use of estrogen alone or estrogen plus progestin (especially sequential regimens) is linked with an increased risk of ovarian cancer. The researchers note “These data expand the range of possible risks associated with menopausal hormone therapy.”
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NIH State of the Science Panel. National Institutes of Health State-of-the-Science Conference Statement: Management of Menopause-Related Symptoms. Ann Intern Med. 2005; 142:1003-1013.
Rossouw JE, Anderson GL, Prentice RL et al. Risks and benefits of estrogen plus progestin in healthy postmenopausal women: principal results from the Women’s Health Initiative randomized controlled trial. JAMA. 2002; 288:321-33.
Anderson GL, Limacher M, Assaf AR et al. Effects of conjugated equine estrogen in postmenopausal women with hysterectomy: the Women’s Health Initiative randomized controlled trial. JAMA . 2004; 291:1701-1712.
 Lacey JV, Brinton LA, Leitzmann MF et al. Menopausal Hormone Therapy and Ovarian Cancer Risk in the National Institutes of Health-AARP Diet and Health Study Cohort. Journal of the National Cancer Institute. 2006;98:1397-405.
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