Endometrial cancer is cancer that starts in the endometrium, the lining of the uterus (womb).

Endometrial cancer is the most common type of uterine cancer. Although the exact cause of endometrial cancer is unknown, increased levels of estrogen appear to play a role. Estrogen helps stimulate the buildup of the lining of the uterus. Studies have shown that high levels of estrogen in animals result in excessive endometrial growth and cancer.

Most cases of endometrial cancer occur between the ages of 60 and 70 years, but a few cases may occur before age 40.

The following increase your risk of endometrial cancer:

• Diabetes
• Estrogen replacement therapy without the use of progesterone
• History of endometrial polyps or other benign growths of the uterine lining
• Infertility (inability to become pregnant)
• Infrequent periods
• Tamoxifen, a drug for breast cancer treatment
• Never being pregnant
• Obesity
• Polycystic ovarian syndrome (PCOS)
• Starting menstruation at an early age (before age 12)
• Starting menopause after age 50

Associated conditions include the following:

• Colon or breast cancer
• Gallbladder disease
• High blood pressure
• Polycystic ovarian disease