Cancer Health Center

The biggest risk factor for endometrial cancer is having too much estrogen and not enough progesterone. This is called "unopposed estrogen." (Your body makes progesterone. Man-made progesterone, as in birth control pills or hormone therapy, is called a progestin.)

Long-term exposure to unopposed estrogen may occur as a result of:

• Being obese. Fat cells make extra estrogen, but the body doesn't make extra progesterone to balance it out.
• Taking estrogen without taking a progestin.
• Taking tamoxifen.
• Polycystic ovary syndrome.
• Beginning your menstrual cycle before age 12 or starting menopause after age 55.
• Not ever being pregnant or not ever completing a full-term pregnancy (nulliparity).
• Not ever breast-feeding.

Other things that increase your risk include:

• Being older than 50. Endometrial cancer is most common in women older than 50.
• Having a history of breast, ovarian, or colon cancer.
• Taking tamoxifen, a breast cancer treatment that acts like estrogen in the uterus.³
• Having endometrial hyperplasia.
• Having type 2 diabetes.
• Having hypertension.
• Having previous radiation therapy to the pelvis.

If you are taking tamoxifen for breast cancer, keep taking it as directed by your doctor. But be sure to have a pelvic exam each year. The risk of endometrial cancer is less than the risk of getting breast cancer again. If you are worried about endometrial cancer risk, talk to your doctor. You might be able to use another medicine, instead of tamoxifen, for breast cancer.

Endometrial cancer has been linked to hereditary nonpolyposis colon cancer (HNPCC). In women, this cancer often starts in the uterus and ovaries before it grows in the colon. The American Cancer Society recommends that a woman with a family history of HNPCC talk to her doctor about annual screenings with endometrial biopsy, starting at age 35.⁴

Reducing your risk

There are some ways to help you lower your risk for endometrial cancer.

• If you are on hormone therapy for menopausal symptoms, taking estrogen with progesterone will keep you from being at extra risk for endometrial cancer. (Women who have had a hysterectomy cannot get endometrial cancer, so taking estrogen without progesterone will not increase their risk for this cancer.)
• Taking birth control pills that contain both estrogen and progestin for longer than 1 year.
• Staying at a healthy body weight.
• Being physically active.
• Eating a diet that is low in animal fats and high in fruits and vegetables.