Risk Factors of Ovarian & Uterine Cancers

Last Updated: Aug. 1, 2003

Ovarian Cancer: Who’s at Risk?
The exact causes of ovarian cancer are not known. However, studies show that the following factors may increase the chance of developing this disease:

Family history. First-degree relatives (mother, daughter, sister) of a woman who has had ovarian cancer are at increased risk of developing this type of cancer themselves. The likelihood is especially high if two or more first-degree relatives have had the disease. The risk is somewhat less, but still above average, if other relatives (grandmother, aunt, cousin) have had ovarian cancer. A family history of breast or colon cancer is also associated with an increased risk of developing ovarian cancer.

Age. The likelihood of developing ovarian cancer increases as a woman gets older. Most ovarian cancers occur in women over the age of 50, with the highest risk in women over 60.

Childbearing. Women who have never had children are more likely to develop ovarian cancer than women who have had children. In fact, the more children a woman has had, the less likely she is to develop ovarian cancer.

Personal history. Women who have had breast or colon cancer may have a greater chance of developing ovarian cancer than women who have not had breast or colon cancer.

Fertility drugs. Drugs that cause a woman to ovulate may slightly increase a woman’s chance of developing ovarian cancer. Researchers are studying this possible association.

Talc. Some studies suggest that women who have used talc in the genital area for many years may be at increased risk of developing ovarian cancer.

Hormone replacement therapy (HRT). Some evidence suggests that women who use HRT after menopause may have a slightly increased risk of developing ovarian cancer.

As we learn more about what causes ovarian cancer, we may also learn how to reduce the chance of getting this disease. Some studies have shown that breast feeding and taking birth control pills (oral contraceptives) may decrease a woman's likelihood of developing ovarian cancer.

Women who have had an operation that prevents pregnancy (tubal ligation) or have had their uterus and cervix removed (hysterectomy) also have a lower risk of developing ovarian cancer. In addition, some evidence suggests that reducing the amount of fat in the diet may lower the risk of developing ovarian cancer.

Women who are at high risk for ovarian cancer due to a family history of the disease may consider having their ovaries removed before cancer develops (prophylactic oophorectomy). This procedure usually, but not always, protects women from developing ovarian cancer. The risks associated with this surgery and its side effects should be carefully considered. A woman should discuss the possible benefits and risks with her doctor based on her unique situation.

Uterine Cancer: Who’s at Risk?
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.

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.

Estrogen. Other risk factors are related to how long a woman’s body is exposed to estrogen. Women who have no children, begin menstruation at a very young age, or enter menopause late in life are exposed to estrogen longer and have a higher risk.

Women with known risk factors and those who are concerned about uterine and ovarian cancers should ask their doctor about the symptoms to watch for and how often to have checkups.

Source: National Cancer Institute

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