Gynecology  Contraception

Oral contraceptives and intrauterine devices (IUD) appear to provide long-term protection against endometrial cancer, researchers report in the International Journal of Cancer. This has been reported by several studies, but few have been conducted in Chinese populations, Dr. Xiao Ou Shu of Vanderbilt University, Nashville, Tennessee, and colleagues note.

NEW YORK (Reuters Health), Tue Nov 21, 2006

To investigate further, the team studied 1,204 women from Shanghai with newly diagnosed endometrial cancer and 1,212 healthy women, matched to the cancer patients for various characteristics. The endometrium is the lining of the uterus, or womb.

Overall, 223 of the cancer patients (18.5 percent) and 302 of the controls (24.9 percent) reported using an oral contraceptive.

After accounting for other known risk factors or protective factors for endometrial cancer, the use of oral contraceptives was associated with a 25 percent reduced risk. The risk decreased with long-term use. After 72 months, the cancer risk was reduced by 50 percent.

This protective effect was maintained, even after 25 years or longer after oral contraceptives were discontinued.

IUD use was associated with a 47 percent lower risk of endometrial cancer. The duration of IUD use, and age when it was first and last use did not significantly alter the association.

The researchers suggest that the "the inverse association between oral contraceptives use and endometrial cancer may be due to the progestin component of oral contraceptives," which may help reduce the overgrowth of cell in the endometrium.

The protective effect of IUDs, they add, may be prompted by "inflammatory actions that eliminate abnormal and precancerous endometrial cells; decreased abnormal cell growth -- a known risk factor for endometrial cancer -- and reduce the concentration of estrogen receptors."

SOURCE: The International Journal of Cancer, November 2006.

© Reuters 2006.