Hormone Therapy Linked to Risk of Ovarian Cancer
Tue Apr 2, 5:39 PM ET

NEW YORK (Reuters Health) - Certain types of hormone replacement therapy may increase the risk of ovarian cancer in women who take the drugs after menopause, according to a study released on Tuesday. Those taking the drugs for more than 10 years seem to be at the greatest risk for ovarian cancer.

However, the increase in risk is relatively modest and should be weighed against the potential health benefits of hormone replacement, according to Dr. Tomas Riman, from Falu Hospital, Sweden, and colleagues. Past studies have shown that hormone replacement therapy can reduce the risk of bone-thinning, and possibly heart disease, though that has not yet been proven.

"We advocate cautious interpretation of our results and do not recommend changes to current hormone replacement therapy prescribing practices," Riman and colleagues report in the April 3rd issue of the Journal of the National Cancer Institute (news - web sites).

"For women to make an informed decision on whether or not to use hormone replacement therapy, all beneficial and adverse hormonal aspects concerning osteoporosis, coronary heart disease, venous thrombosis (blood clot formation) and other health effects must be addressed," they add.

In the study, the researchers compared 655 women with ovarian cancer to nearly 4,000 healthy women the same age. All the women were 50 to 74 years of age.

Compared with women who had never used estrogen replacement therapy, women who took estrogen alone were at increased risk of ovarian cancer.

Women who used estrogen with sequentially added progestins--a cyclic regimen of the second hormone--were also at an increased risk of ovarian cancer compared with women who had never used estrogen.

However, women who used hormone replacement therapy with continuously (daily) added progestins were no more likely to develop ovarian cancer than those who never had used hormones. Taking estrogen alone is know to increase the risk of cancer of the uterine lining, so most women now also take progestin, a synthetic form of the hormone progesterone, as part of hormone replacement therapy.

The greatest increased risk of ovarian cancer was seen among women who had used estrogen with sequentially added progestins for more than 10 years.

However, the researchers note that the possible increase in risk is still relatively modest. Of 1,000 women taking estrogen alone or in combination with sequential progestin, 2 to 3 might develop ovarian cancer as a result of the treatment.

SOURCE: Journal of the National Cancer Institute 2002;94:497-504