According to the results of a study published in The Lancet, current users of postmenopausal hormones have a slightly increased risk of developing and dying from ovarian cancer.
Estrogen, with or without progestin, is an effective treatment for many menopausal 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.
More recently, studies have 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 evaluated information from the U.K. Million Women Study. This study enrolled close to one million postmenopausal women who were free of cancer at the start of the study.
The average age of the study participants was 57 years. Roughly 30% of study participants were currently using postmenopausal hormones, 20% had previously used postmenopausal hormones, and 50% had never used postmenopausal hormones.
- Compared to never-users of postmenopausal hormones, current users were 20% more likely to develop ovarian cancer. No increase in risk of ovarian cancer was apparent among past users of postmenopausal hormones.
- Risk of ovarian cancer among current users of postmenopausal hormones increased with duration of use. Women who had used postmenopausal hormones for between five and nine years had a 24% increase in risk of ovarian cancer, and women who had used postmenopausal hormones for 10 years or longer had a 31% increase in risk of ovarian cancer. In contrast, women who had used postmenopausal hormones for fewer than five years did not have a significantly increased risk of ovarian cancer.
- Risk of ovarian cancer among current users of postmenopausal hormones did not vary substantially by type of hormone therapy (estrogen only versus estrogen plus progestin).
The researchers conclude that women who use postmenopausal hormones are at increased risk of developing and dying of ovarian cancer. Women who are currently using postmenopausal hormones, or who are considering using postmenopausal hormones, are encouraged to discuss the risks and benefits with their physician.
 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.