Study Links Estrogen Use to Risk of Ovarian Cancer

Taking estrogen for 10 years or more after menopause doubled women’s risk of fatal ovarian cancer, says a new study that adds to the confusion facing millions of Americans debating whether to use the hormone.

Estrogen users shouldn’t panic: Ovarian cancer is rare enough that few estrogen users died despite the increased risk, especially compared to bigger killers, such as heart disease, that estrogen might help, experts cautioned.

Also, most of the women studied used estrogen alone. Yet today, taking estrogen plus the hormone progestin is recommended for any post-menopausal woman who hasn’t had a hysterectomy. Nobody knows if combination hormone therapy also increases risk or if adding progestin might instead protect the ovaries.

Despite those important caveats, the American Cancer Society study promises to deepen women’s dilemma about who should use estrogen and for how long. About 20 million Americans use either combination hormone therapy or estrogen alone.

“I do understand these findings can be frightening for a woman,” said epidemiologist Dr. Carmen Rodriguez, whose study is in the Journal of the American Medical Assn., which was dedicated this week to women’s health.

But she stressed that for many women estrogen is helpful.

More research is needed to prove the link between long-term estrogen use and ovarian cancer, cautioned Dr. Diane Bodurka-Bevers of the M.D. Anderson Cancer Center in Houston.

Until then, stay tuned to the latest discoveries when considering hormone therapy, Bodurka-Bevers advised. “Every day there’s new information. The story is not complete to date.”

Estrogen therapy can prevent bone-thinning osteoporosis and treat hot flashes and other menopausal symptoms. There is evidence but not proof that it may decrease risk of heart disease and colon cancer. But it can cause uterine cancer--a risk that adding progestin offsets--and long-term use can increase the risk of breast cancer.

Rodriguez tracked 211,581 post-menopausal women from 1982 to 1996; 944 died of ovarian cancer.

Comparing estrogen users with nonusers showed that just a few years of estrogen therapy didn’t affect ovarian cancer risk, while using it for 10 or more years roughly doubled the risk.

Rodriguez said 43 of every 100,000 women age 65 or older die of ovarian cancer annually, while 414 die of heart disease. Doubling ovarian deaths to 86 per 100,000 women is still far fewer lives than heart disease claims, she said.