Increased risk linked to estrogen replacement therapy.(increased ovarian cancer risk)

2002 AUG 15 - (NewsRx.com & NewsRx.net) -- Researchers from the National Cancer Institute (NCI) have found that women in a large study who used estrogen replacement therapy after menopause were at increased risk for ovarian cancer. The report was published in the July 17, 2002, issue of the Journal of the American Medical Association.

The scientists followed 44,241 women for approximately 20 years. Compared with postmenopausal women not using hormone replacement therapy, users of estrogen-only therapy had a 60% greater risk of developing ovarian cancer. The risk increased with length of estrogen use. The women, who were followed from 1979 to 1998, were former participants in the Breast Cancer Detection Demonstration Project, a mammography screening program conducted between 1973 and 1980.

"The main finding of our study was that postmenopausal women who used estrogen replacement therapy for 10 or more years were at significantly higher risk of developing ovarian cancer than women who never used hormone replacement therapy," said James V. Lacey Jr., PhD, lead author of the study from NCI's division of cancer epidemiology and genetics.

The relative risk for 10 to 19 years of use was 1.8, which translates to an 80% higher risk than nonusers, and increased to 3.2 (a 220% higher risk than nonusers) for women who took estrogen for 20 or more years.

Estrogen is a natural hormone produced primarily by the ovaries. After menopause, the ovaries produce lower levels of the hormones estrogen and progesterone. By the time natural menopause is complete - usually between ages 45 and 55 - hormone output decreases significantly.

As early as the 1940s, women began using estrogens in high doses to counteract some of the short-term discomforts of menopause (hot flashes, vaginal drying and thinning, and urinary tract incontinence and infections).

However, after it became clear in the 1970s that women who took estrogen alone had a six to eight times higher risk of developing endometrial cancer (cancer of the lining of the uterus), doctors began prescribing progestin along with much lower doses of estrogen. Progestin is a synthetic form of the natural hormone progesterone. The addition of progestin to estrogen therapy reduces the increased risk of endometrial cancer associated with using estrogen alone. As a result, it has become increasingly common to prescribe estrogen-progestin therapy for women who have not had a hysterectomy.