The ovary is a female reproductive organ located in the pelvis. Its function is to produce female hormones and to store eggs that, if fertilized by sperm, can develop into a baby. Women have two ovaries, one on each side of the uterus.

Tumors found in the ovaries may be noncancerous tissue growths (cysts) or cancerous growths that may spread to other parts of the body.

Significance of ovarian cancer

In the United States, more women die of ovarian cancer each year than of cervical and endometrial cancers combined. Survival rates have not greatly improved, and screening has not been proven to decrease the death rate.

Ovarian cancer prevention

Ovarian cancer can sometimes be associated with known risk factors for the disease. Many risk factors are modifiable though not all can be avoided. Avoiding risk factors when possible and increasing protective factors may help prevent ovarian cancer.

GENETIC FACTORS: Women who have inherited certain altered (mutated) genes have a much higher risk of developing ovarian cancer. These mutations may be found in BRCA1, BRCA2, or hereditary nonpolyposis colon cancer (HNPCC) genes. For more information on groups that are at high risk for ovarian cancer due to inherited genetic factors, see the PDQ summary on the Genetics of Breast and Ovarian Cancer.

AGE: The risk of developing ovarian cancer increases as a woman gets older.

OBESITY: Having excess body fat as measured by body mass index, including during the teen years, increases the risk of ovarian cancer. Diet and nutrition during the teen years may play a role in prevention.

ORAL CONTRACEPTIVES: Studies show that the use of oral contraceptives reduces the risk of developing ovarian cancer. The longer you use oral contraceptives, the lower your risk might be. The decrease in risk may last up to 25 years after the use of oral contraceptives has ended. This lower risk is seen both in women who have given birth and in women who have not. Oral contraceptives may also protect against ovarian cancer in women who are at higher risk because they have inherited an altered version of BRCA1 and BRCA2 genes.

Harms from taking oral contraceptives include:

• A higher risk of blood clots that can block blood vessels, especially in smokers.
• A slightly higher short-term risk of breast cancer that decreases over time when use is stopped.

CHILDBEARING AND BREAST-FEEDING: Women who have had at least one child are less likely to develop ovarian cancer than women who have never had children. Studies have also shown that women who breast-feed are less likely to develop ovarian cancer.

TUBAL LIGATION OR HYSTERECTOMY: Studies have shown that women who have undergone tubal ligation (sterilization) or hysterectomy are at decreased risk of developing ovarian cancer.