How does menopausal hormone use affect the risk of ovarian cancer?

Several observational studies have found that the use of estrogen alone is associated with a slightly increased risk of ovarian cancer for women who used this hormone for 10 or more years. One observational study that followed 44,241 menopausal women for approximately 20 years concluded that women who used estrogen alone for 10 or more years were twice as likely to develop ovarian cancer compared with women who did not use menopausal hormones. Another large observational study also found an association between estrogen use and death due to ovarian cancer. In this study, the increased risk appeared to be limited to women who used estrogen for 10 or more years.

The results from the million women study showed that women currently using menopausal hormones had an increased risk of developing ovarian cancer and a 20 percent likelihood of dying from the disease compared with nonusers. However, the increased risk disappeared after hormone use stopped.

Data from the Women's Health Initiative (WHI) estrogen-plus-progestin study indicate that there may be an increased risk of ovarian cancer with use of estrogen plus progestin. After 5.6 years of follow-up, a 58 percent increased risk of ovarian cancer was reported in women using estrogen plus progestin compared with nonusers, but the increased risk was not statistically significant. One observational study suggested that regimens of estrogen plus progestin do not increase the risk of ovarian cancer if progestin is used for more than 15 days per month, but this study was too small to draw firm conclusions. More research is needed to clarify the relationship between menopausal hormone use, particularly for estrogen plus progestin, and the risk of ovarian cancer.

This answer is based on source information from the National Cancer Institute.

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