A risk factor, however, is not something that necessarily causes cancer. Researchers often do not know what makes a risk factor a risk. Finding the actual cause of endometrial cancer is an important area of cancer research. Obesity Studies have estimated that women with excess body weight have a 2-5x greater risk of developing endometrial cancer than women with no excess body weight. The relationship between these risk factors and endometrial cancer is unclear, although obesity may play a role.
Pregnancy is a period of intense progesterone stimulation by the placenta.
Because progesterone counterbalances the growth-stimulating effects of estrogen, women who have experienced pregnancy are at a lower risk for developing endometrial cancer. Women who started menstruating at an early age or stopped at a late age might have a higher risk for developing endometrial cancer. Estrogen replacement therapy Estrogen replacement therapy that is used to relieve the symptoms of menopause puts women at high risk for endometrial cancer. It is believed that the increase in endometrial cancer that occured in the U.S. in the 1970s was due to the introduction and widespread use of postmenopausal estrogen therapy. The risk is reduced when the estrogen is combined with progesterone.