No one knows the exact causes of uterine cancer. However, it is clear that this disease is not contagious. No one can "catch" cancer from another person. Women who get this disease are more likely than other women to have certain risk factors. A risk factor is something that increases a person's chance of developing the disease. Most women who have known risk factors do not get uterine cancer. On the other hand, many who do get this disease have none of these factors. Doctors can seldom explain why one woman gets uterine cancer and another does not. Studies have found the following risk factors:
- Age: Cancer of the uterus occurs mostly in women over age 50.
- Endometrial hyperplasia: The risk of uterine cancer is higher if a woman has endometrial hyperplasia. This condition and its treatment are described above.
- Hormone replacement therapy (HRT): HRT is used to control the symptoms of menopause, to prevent osteoporosis (thinning of the bones), and to reduce the risk of heart disease or stroke. Women who use estrogen without progesterone have an increased risk of uterine cancer. Long-term use and large doses of estrogen seem to increase this risk. Women who use a combination of estrogen and progesterone have a lower risk of uterine cancer than women who use estrogen alone. The progesterone protects the uterus. Women should discuss the benefits and risks of HRT with their doctor. Also, having regular checkups while taking HRT may improve the chance that the doctor will find uterine cancer at an early stage, if it does develop.
- Obesity and related conditions: The body makes some of its estrogen in fatty tissue. That's why obese women are more likely than thin women to have higher levels of estrogen in their bodies. High levels of estrogen may be the reason that obese women have an increased risk of developing uterine cancer. The risk of this disease is also higher in women with diabetes or high blood pressure (conditions that occur in many obese women).
- Tamoxifen: Women taking the drug tamoxifen to prevent or treat breast cancer have an increased risk of uterine cancer. This risk appears to be related to the estrogen-like effect of this drug on the uterus. Doctors monitor women taking tamoxifen for possible signs or symptoms of uterine cancer. The benefits of tamoxifen to treat breast cancer outweigh the risk of developing other cancers. Still, each woman is different. Any woman considering taking tamoxifen should discuss with the doctor her personal and family medical history and her concerns.
- Race: White women are more likely than African-American women to get uterine cancer.
- Colorectal cancer: Women who have had an inherited form of colorectal cancer have a higher risk of developing uterine cancer than other women.