Hormone therapy and the risk of ovarian cancer

Ovarian cancer is a rare but deadly disease among women. Taking hormone replacement therapy (HRT) or estrogen replacement therapy (ERT) after menopause seems to increase the risk of ovarian cancer, although that risk remains low overall.1

Because overall lifetime risk of developing ovarian cancer is low, discuss your individual risk factors with your doctor before you make the decision about continuing or starting ERT or HRT after menopause.

Estrogen replacement therapy (ERT)

One study has shown a slightly increased risk of ovarian cancer from long-term ERT use.1 Estrogen use following menopause also increases the risk of hormone-related cancers, such as breast cancer and, when taken without progestin, endometrial cancer.2

The average lifetime risk of ovarian cancer is low. The annual death rate from ovarian cancer is:3

  • 64 out of 100,000 women who are taking estrogen and have been for 10 years or longer.
  • 38 out of 100,000 women who used estrogen for 10 years or longer but stopped using it.
  • 26 out of 100,000 women who never used estrogen.

No evidence of a further increase in risk was found with 15 years of estrogen use. Risk rates decreased in women who stopped using ERT, and no increase in risk was found in women who had taken estrogen replacement therapy for 15 years or longer.3

Hormone replacement therapy (HRT)

The Women's Health Initiative (WHI) randomized HRT trial has found a slight increase in ovarian cancer with HRT use of less than 6 years. This increase is smaller than with ERT ovarian cancer risk. The WHI experts advise that ovarian cancer risk from using HRT should not be a top consideration for most women who are deciding whether to take HRT.4


  1. Beral V, et al. (2007). Ovarian cancer and hormone replacement therapy in the Million Women Study. Lancet, 369(9574): 1703–1710.
  2. Million Women Study Collaborators (2003). Breast cancer and hormone-replacement therapy in the Million Women Study. Lancet, 362(9382): 419–427.
  3. Rodriguez C, et al. (2001). Estrogen replacement therapy and ovarian cancer mortality in a large prospective study of U.S. women. JAMA, 285(11): 1460–1463.
  4. Anderson GL, et al. (2003). Effects of estrogen plus progestin on gynecologic cancers and associated diagnostic procedures: The Women's Health Initiative randomized trial. JAMA, 290(13): 1739–1748.

Last Updated: May 16, 2008

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