Cancer of the ovaries accounts for only three percent of all cancers in women in the United States. About 22,000 cases were estimated for the year 2013 (with about 14,000 deaths expected). It is the ninth most common cancer among women in this country, but it is the deadliest among gynecologic cancers. Most ovarian cancer occurs among midlife and older women; more than half of all women diagnosed with ovarian cancer are over age 60.
The exact causes of ovarian cancer are still unknown. Possible risk factors include a family history of ovarian cancer; few or no pregnancies; the use of fertility-stimulating drugs; a history of breast, colorectal, or endometrial cancer; exposure to industrial products, including asbestos, or to high levels of radiation; a diet high in fat; and the use of estrogens other than the birth control pill. (In one large study, the risk of developing ovarian cancer was higher in women who used menopausal hormone therapy than in women who never used such therapy, but the increased risks varied by type and duration of hormone and regimen, as well as by whether a woman had had a hysterectomy).
Using talcum powder in the genital area has long been suspected as a risk factor, but so far evidence points to an elevated risk for only one type of relatively rare ovarian cancer. Oral contraceptive use is protective against ovarian cancer, as is having multiple pregnancies. Having a tubal ligation also appears to reduce risk.
One reason the death rate is so high is that most ovarian cancer is found in the later stages, when it is harder to treat effectively. When it is found early, about 90 percent of the women treated survive at least five years.
Ovarian cancer does not always have clear symptoms. Its warning signs—which may be vague and are frequently dismissed as stress or nerves—include indigestion, gas, bowel disturbances, loss of appetite or weight, a feeling of fullness, enlargement or bloating of the abdomen, lower abdominal discomfort or pain, unexplained weight gain, frequent urination, fatigue, backache, nausea, vomiting, nonmenstrual vaginal bleeding, or pain during intercourse. Most of these are relatively common complaints in midlife women.
If you have persistent symptoms or a family history of ovarian cancer, your gynecologist should do a thorough evaluation. In some cases, you may need to be referred to a gynecological oncologist, who specializes in cancer diagnosis and treatment. The screening tests now available for ovarian cancer are not very accurate, so there is still no good routine testing method for women with no symptoms and no risk factors. A blood test for a protein called CA‑125 is not enough to diagnose ovarian cancer, because many other conditions can also raise the level of CA‑125 in the blood; therefore, it needs to be used in combination with other tests.
Diagnostic tests for cancer of the ovaries include pelvic ultrasound, computerized tomography (CT or CAT scan), magnetic resonance imaging (MRI), and surgery, the only conclusive diagnostic tool. Exploratory surgery (laparotomy) is used for diagnosis, staging, and, frequently, tumor reduction.
About 5 to 7 percent of ovarian cancer cases are associated with an inherited risk factor, and removal of an ovary or ovaries (oophorectomy) has been shown to be an effective way to avoid breast cancer in women who carry a BRCA1 or BRCA2 gene mutation. Discuss all the benefits and harms of a prophylactic oophorectomy with your healthcare provider.
Medical Treatments for Ovarian Cancer
Early detection, prompt diagnosis, and accurate staging are necessary for the successful treatment of ovarian cancer. Treatment depends on the stage of the disease at the time of diagnosis, the type of cells that make up the tumor, and how fast the cancer is growing. The current standard medical options for treating ovarian cancer include surgery, chemotherapy, and/ or radiation. Immunotherapies, including interferon, interleukin, bone marrow or stem cell transplants, and monoclonal antibodies, are also available in clinical and/or research settings.
More research is needed to better understand the causes of ovarian cancer and to find more effective diagnostic tests and treatments.
For more information on stages and different types of ovarian cancer and treatments, see Ovarian Cancer from the National Cancer Institute.