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 ACS 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 your 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 have (or have had) ovarian cancer, especially if they developed ovarian cancer at a young age. 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.

Breast cancer: If you have had breast cancer, you also have an increased risk of developing ovarian cancer. There are several reasons for this. Some of the reproductive risk factors for ovarian cancer may also increase breast cancer risk. Also, if you have a strong family history of breast cancer, you may have an inherited mutation of the BRCA1 or BRCA2 gene.

Talcum powder: It has been suggested that talcum powder applied directly to the genital area or on sanitary napkins may be carcinogenic (cancer-causing) to the ovaries. Most, but not all, studies suggest a slight increase in risk of ovarian cancer in women who used talc on the genital area. In the past, talcum powder was sometimes contaminated with asbestos, a known cancer-causing mineral. This may explain the association with ovarian cancer in some studies. Body and face powder products have been required by law for more than 20 years to be asbestos-free. However, proving the safety of these newer products will require follow-up studies of women who have used them for many years. There is no evidence at present linking cornstarch powders with any female cancers.

Estrogen replacement therapy and hormone replacement therapy: Some studies suggest women using estrogens after menopause have an increased risk of developing ovarian cancer, but other studies have not found any effect on ovarian cancer risk. A recent study suggested that using estrogen replacement therapy (ERT) increases the risk of developing ovarian cancer, and that the risk increases with continued use. The risk among women who used ERT for longer than 10 years was almost double that of women who had never used it, and the risk among those who used it for 20 years or more was tripled. (Remember, however, that the average lifetime risk for ovarian cancer is only about 2%.) Most of these findings have been for women taking estrogen alone, not for those taking combined progesterone and estrogen. Recently, a study of women taking both drugs found that these women also have an increased rate of ovarian cancer.

Revised: 09/08/2004