Risk factors

Factors that increase the risk of endometrial cancer include:

• Changes in the balance of female hormones in the body. The ovaries make two main female hormones — estrogen and progesterone. Fluctuations in the balance of these hormones cause changes in the endometrium.

  A disease or condition that increases the amount of estrogen, but not the level of progesterone, in your body can increase your risk of endometrial cancer. Examples include irregular ovulation patterns, which might happen in polycystic ovary syndrome, obesity and diabetes. Taking hormones after menopause that contain estrogen but not progesterone increases the risk of endometrial cancer.

  A rare type of ovarian tumor that secretes estrogen also can increase the risk of endometrial cancer.

• More years of menstruation. Starting menstruation at an early age — before age 12 — or beginning menopause later increases the risk of endometrial cancer. The more periods you've had, the more exposure your endometrium has had to estrogen.
• Never having been pregnant. If you've never been pregnant, you have a higher risk of endometrial cancer than someone who has had at least one pregnancy.
• Older age. As you get older, your risk of endometrial cancer increases. Endometrial cancer occurs most often after menopause.
• Obesity. Being obese increases your risk of endometrial cancer. This may occur because excess body fat alters your body's balance of hormones.
• Hormone therapy for breast cancer. Taking the hormone therapy drug tamoxifen for breast cancer can increase the risk of developing endometrial cancer. If you're taking tamoxifen, discuss this risk with your doctor. For most, the benefits of tamoxifen outweigh the small risk of endometrial cancer.
• An inherited colon cancer syndrome. Lynch syndrome, also called hereditary nonpolyposis colorectal cancer (HNPCC), is a syndrome that increases the risk of colon cancer and other cancers, including endometrial cancer. Lynch syndrome is caused by a gene mutation passed from parents to children. If a family member has been diagnosed with Lynch syndrome, discuss your risk of the genetic syndrome with your doctor. If you've been diagnosed with Lynch syndrome, ask your doctor what cancer screening tests you should undergo.