Uterine cancer risk factors: what raises and lowers the risk

What uterine cancer is

Uterine cancer forms in the tissues of the uterus (womb). There are two types. Endometrial cancer is the most common type and begins in the cells lining the uterus, the endometrium. Uterine sarcoma is rare, more aggressive and harder to treat; it begins in muscle or other tissues of the uterus (MedlinePlus).

Uterine cancer usually happens after menopause. The cause is unknown, but factors and conditions that change the balance of hormones in the body may raise the risk (MedlinePlus).

Risk factors linked to estrogen

Estrogen can affect the growth of some cancers, including endometrial cancer. NCI lists these ways of being exposed to estrogen as raising the risk (NCI risk factors):

• Estrogen-only hormone therapy after menopause. The risk grows higher the longer it is used. For this reason, estrogen alone is usually prescribed only for women who do not have a uterus. Estrogen combined with progestin does not raise the risk of endometrial cancer after menopause, but it does raise the risk of breast cancer (NCI risk factors).
• Early first period. Starting periods at an early age adds years of estrogen exposure (NCI risk factors).
• Late menopause. Reaching menopause at an older age also means a longer time exposed to estrogen (NCI risk factors).
• Never being pregnant. Estrogen levels are lower during pregnancy, so women who have never been pregnant are exposed to estrogen for longer (NCI risk factors).

Other risk factors

• Tamoxifen. Using tamoxifen for more than 2 years raises the risk of endometrial cancer, and the risk is greater after menopause. Raloxifene, used to prevent bone weakness after menopause, has not been shown to raise it (NCI risk factors). If you are weighing these medicines to lower breast cancer risk, the breast cancer risk-reducing medication check covers who they are offered to.
• Obesity, weight gain and metabolic syndrome. Having obesity or gaining weight as an adult raises the risk, and so does metabolic syndrome (extra fat around the waist, high blood sugar, high blood pressure and high triglycerides) (NCI risk factors). The BMI calculator shows where your weight falls.
• Type 2 diabetes. It may raise the risk (NCI risk factors).
• Endometrial hyperplasia. This is an abnormal thickening of the lining of the uterus. It is not cancer, but in some cases it may lead to endometrial cancer (NCI risk factors).
• Lynch syndrome. Women with this inherited disorder have a much higher risk of endometrial cancer than women without it (NCI risk factors). Lynch syndrome also raises colorectal cancer risk; see colorectal cancer risk factors.
• Polycystic ovary syndrome and Cowden syndrome. Both are linked to a higher risk (NCI risk factors).
• Family history. Having a mother, sister or daughter who had endometrial cancer raises the risk (NCI risk factors) (MedlinePlus).

For uterine sarcoma, the rarer type, MedlinePlus lists past radiation therapy to the pelvis and taking tamoxifen (MedlinePlus).

NCI advises talking to your doctor or other health care professional about how you might lower your risk (NCI risk factors).

What may lower the risk

NCI lists these protective factors (NCI risk factors):

• Pregnancy and breast-feeding. The risk is lower in women who have had children, and breast-feeding also lowers it.
• Combined birth control pills. Pills that combine estrogen and progestin lower the risk. The effect grows the longer they are used and can last for many years after stopping. They also bring a higher risk of blood clots, stroke and heart attack, especially in women who smoke and are older than 35. New data suggest other hormonal contraceptives, such as devices placed in the uterus, may also lower the risk.
• Bariatric surgery. It is not known whether losing weight lowers the risk, but bariatric (weight loss) surgery does. The surgery has its own risks.
• Physical activity. Exercise, including activity at work or at home, may lower the risk.

A diet with fruits, vegetables, soy or vitamin D has not been found to change the risk, and there is not enough evidence to show a link between hair products and endometrial cancer (NCI risk factors).

Signs to check with a doctor

Abnormal vaginal bleeding is the most common symptom of both endometrial cancer and uterine sarcoma (MedlinePlus). NCI says to check with your doctor if you have any of these (NCI symptoms):

• vaginal bleeding or discharge not related to your period
• vaginal bleeding after menopause
• difficult or painful urination
• pain during sex
• pain in the pelvic area

Screening: what NCI says

There is no standard or routine screening test for endometrial cancer. It usually causes symptoms, such as vaginal bleeding, and is found at an early stage, when there is a good chance of recovery (NCI screening).

A Pap test is not used to screen for endometrial cancer. Studies have not shown that screening with transvaginal ultrasound or endometrial sampling lowers deaths from it. For women who have or are at risk for hereditary nonpolyposis colon cancer (Lynch syndrome), experts suggest yearly transvaginal ultrasound starting as early as age 25. For women taking tamoxifen, ultrasound is not useful without symptoms but should be used if there is vaginal bleeding (NCI screening).

Related guides: ovarian cancer risk factors and breast cancer risk factors. All cancer checks are on the cancer screening hub.

Common questions

Is uterine cancer the same as endometrial cancer?

Endometrial cancer is the most common type of uterine cancer. The other type, uterine sarcoma, is rare (MedlinePlus).

Does hormone therapy cause uterine cancer?

Estrogen-only hormone therapy after menopause raises the risk of endometrial cancer, more so the longer it is used. Estrogen combined with progestin does not raise endometrial cancer risk but does raise breast cancer risk (NCI risk factors). Talk with your doctor about the benefits and risks for you (MedlinePlus).

Can a Pap test find uterine cancer?

Pap tests are not used to screen for endometrial cancer, though results sometimes show signs of an abnormal uterine lining that lead to more tests (NCI screening). Pap tests screen for cervical cancer; see cervical cancer risk factors.