Contraceptives protect against uterine cancer

Oral contraceptives and intrauterine devices (IUD) appear to provide long-term protection against endometrial cancer. The endometrium is the inner layer of the uterus. Researchers from the Vanderbilt University, Nashville, Tennessee, China, studied 1,204 women from Shanghai with newly diagnosed endometrial cancer and 1,212 healthy women, matched to the cancer patients for various characteristics. Overall, 223 of the cancer patients (18 percent) and 302 of the controls (25 percent) reported using an oral contraceptive. After accounting for other known risk factors or protective factors for endometrial cancer, it was found that 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. It was also found that 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 used did not significantly alter the association. 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 cells in the endometrium. The protective effect of IUDs may be prompted by inflammatory actions that eliminate abnormal and pre-cancerous endometrial cells; decreased abnormal cell growth - a known risk factor for endometrial cancer - and reduce the concentration of oestrogen receptors.