Possible Causes and Prevention

Scientists at hospitals and medical centers all across the country are studying uterine cancer. They are trying to learn more about what causes the disease and how to prevent it.

At this time, we do not know exactly what causes uterine cancer, and doctors can seldom explain why one woman gets this disease and another does not. It is clear, however, that uterine cancer is not caused by an injury, and is not contagious; no one can "catch" uterine cancer from another person.

By studying patterns of cancer in the population, researchers have found certain factors that are more common in women who get uterine cancer than in those who don't get this disease. It is important to know that most women with these risk factors do not get cancer, and many who do get uterine cancer have none of these factors.

The following are some of the known risk factors for this disease:

• Age. Cancer of the uterus is most common in women over age 50.

• Endometrial hyperplasia. Women who have endometrial hyperplasia have a higher risk of developing uterine cancer. This condition and its treatment are described in the What Is Cancer? section.

• Estrogen replacement therapy. Women who use estrogen replacement therapy to control symptoms associated with menopause, to prevent osteoporosis (thinning of the bones), or to reduce the risk of heart disease or stroke may have an increased risk of uterine cancer. Long-term treatment and large doses seem to increase this risk. Using a combination of estrogen and progesterone decreases the risk linked to the use of estrogen alone. The progesterone protects the endometrium from the cancer-causing effect of estrogen. A woman considering hormone replacement therapy should discuss the benefits and risks with her doctor. Regular follow-up visits with a health professional while taking estrogen replacement therapy may improve the chances of detecting and treating uterine cancer in the early stages should it develop.

• Overweight. Scientists believe that too much estrogen may be the reason why overweight women are more than twice as likely to develop uterine cancer as women of normal weight. Because fat converts certain hormones into a form of estrogen, women with excess fat produce higher levels of estrogen.

• Diabetes and high blood pressure. Some studies suggest that diabetes and high blood pressure increase the risk of uterine cancer. Because these conditions often occur in overweight people, researchers cannot be certain whether the conditions themselves or the relationship between body fat and estrogen levels increases uterine cancer risk.

• Other cancers. Women with a history of colon cancer, rectal cancer, or breast cancer have a slightly higher risk of developing uterine cancer than do most other women. Women who have had uterine cancer also have an increased risk of developing certain other cancers.

• Tamoxifen. An increased risk of developing uterine cancer has been found in women taking the drug tamoxifen for the treatment of breast cancer. This risk may be related to the estrogen-like effect of this drug on the uterus. Women taking tamoxifen should be closely monitored by the doctor for possible signs or symptoms of uterine cancer. Doctors emphasize that the benefits of tamoxifen as a treatment for breast cancer are firmly established and far outweigh the potential risk of other cancers.

• Race. White women have a greater chance of developing uterine cancer than black women.

• Other risk factors for uterine cancer are also related to estrogen, including having few or no children or entering menopause late in life. Some studies of women who have used oral contraceptives that combine estrogen and progesterone show that these women have a lower than average risk of uterine cancer.

Women with known risk factors and those who are concerned about uterine cancer should talk with their doctor about the disease, the symptoms to watch for, and an appropriate schedule for checkups. The doctor's advice will be based on the woman's age, medical history, and other factors.

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