ovarian cancer ; What Are the Risk Factors for Ovarian Cancer?

A risk factor is anything that increases your chance of getting a disease such as cancer. Different cancers have different risk factors. For example, unprotected exposure to strong sunlight is a risk factor for skin cancer. Smoking is a risk factor for cancers of the lung, mouth, larynx, bladder, kidney, and several other organs.

Researchers have discovered several specific factors that increase a woman's likelihood of developing epithelial ovarian cancer. These risk factors do not apply to other less common types of ovarian cancer such as germ cell tumors and stromal tumors.

Most women with ovarian cancer do not have any known risk factors. Risk factors increase the odds of getting a disease but do not guarantee it will occur. Only a small number of women who have risk factors will develop ovarian cancer.

Age: Most ovarian cancers develop after menopause. A woman is considered to be menopausal when she has gone a year without a menstrual period. Half of all ovarian cancers are found in women over the age of 63.

Obesity: A study from the American Cancer Society found a higher rate of death from ovarian cancer in obese women. The risk was increased by 50% in the heaviest women.

Reproductive history: Women who started menstruating at an early age (before age 12), had no children or had their first child after age 30, and/or experienced menopause after age 50 may have an increased risk of ovarian cancer. There seems to be a relationship between the number of menstrual cycles in a woman's lifetime and her risk of developing ovarian cancer.

Fertility drugs: In some studies, researchers have found that prolonged use of the fertility drug clomiphene citrate, especially without achieving pregnancy, may increase the risk for developing ovarian tumors, particularly a type known as "tumors of low malignant potential" (LMP tumors). If you are taking this drug, you should discuss its potential risks with your doctor. However, infertility also increases the risk of ovarian cancer, even without use of fertility drugs. More research to clarify these relationships is now underway.

Family history of ovarian cancer, breast cancer, or colorectal cancer:Your ovarian cancer risk is increased if your mother, sister, or daughter has (or have had) ovarian cancer, especially if she developed ovarian cancer at a young age. Two-thirds of women who develop ovarian cancer are over 55 years old. If your relative had ovarian cancer when she was younger than 55, that may be a sign that your risk is even higher. The younger your relative was when she developed ovarian cancer, the higher your risk. You can inherit an increased risk for ovarian cancer from relatives on your mother's side or father's side of the family. About 10% of ovarian cancers result from an inherited tendency to develop the disease. If there is a family history of cancer caused by an inherited mutation (change) of the breast cancer gene BRCA1 or BRCA2, you have a very high risk of ovarian cancer. Also, a mutation leading to inherited colorectal cancer can increase the risk of ovarian cancer. Many cases of familial epithelial ovarian cancer are caused by inherited gene mutations that can be identified by genetic testing.
Women with ovarian cancers caused by these inherited gene mutations tend to have a better prognosis than patients who do not have any family history of ovarian cancer. (See the section on causes of ovarian cancer for information on these gene mutations.)

Genetic counseling, genetic testing, and strategies for preventing ovarian cancer in women with an increased familial risk are discussed in the prevention section of this document.

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