Ovarian Cancer

Causes & Risk Factors

The exact causes of ovarian cancer are not known. However, studies show that the following risk factors for ovarian cancer 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 ovarian cancer risk factor.

  • 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 ovarian cancer risk factor 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.

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

About 1 in every 57 women in the United States will develop ovarian cancer. Most cases occur in women over the age of 50, but this disease can also affect younger women.

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. These factors decrease the number of times a woman ovulates, and studies suggest that reducing the number of ovulations during a woman's lifetime may lower the risk of 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 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 have higher risk factors 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.

Having one or more of the ovarian cancer risk factors mentioned here does not mean that a woman is sure to develop ovarian cancer, but their chance may be higher than average. Women who are concerned about ovarian cancer may want to talk with a doctor who specializes in treating women with cancer: a gynecologist, a gynecologic oncologist, or a medical oncologist. The doctor may be able to suggest ways to reduce the likelihood of developing ovarian cancer and can plan an appropriate schedule for checkups.

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