Health A-Z

Medical Content Created by the Faculty of the
Harvard Medical School

Ovarian Cancer

What Is It?

Ovarian cancer is the uncontrolled growth of abnormal cells in the ovaries, the female reproductive organs that produce eggs. Ovarian cancer cells come from one of three areas in the ovary. Cancer cells forming in the surface layer of the ovary (epithelial carcinoma) are the most common. Cancer cells forming from the egg-producing cells (germ cell tumors) and from the supportive tissues within the ovaries (stromal tumors) are less common.

The disease often does not cause any symptoms until it has spread beyond the ovaries, the late stage of ovarian cancer. It is difficult for a physician to detect ovarian cancer during a pelvic exam before this late stage. This helps to explain why ovarian cancer leads to death more often than some other cancers. Ovarian cancer accounts for more deaths than any other cancer of the female reproductive system. An estimated 15,520 women are expected to die of ovarian cancer in the United States during 2008, according to the latest statistics from the American Cancer Society.

Symptoms of ovarian cancer may be mild and imitate less serious problems even though the disease has spread to other organs. Symptoms can be vague and include frequent urination and bloating. For these reasons, about 75% of ovarian cancer cases aren't identified until the later, more dangerous, stages of the disease. Researchers are trying to develop screening tests that can detect ovarian cancer during its early stage because it's more likely the disease can be cured or controlled when it is treated in the early stage.

The exact causes of ovarian cancer are unknown, but a number of risk factors have been identified. The disease has a strong genetic (inherited) component, and women who have had a first-degree relative (sister, mother or daughter) diagnosed with ovarian cancer are at a high risk of developing the disease, as are women who have a relative who has had breast or colon cancer. The likelihood of developing ovarian cancer also increases with age. Most ovarian cancers occur in women over age 50, and the highest risk is in women over 60. Women who have never had children are more likely to develop ovarian cancer.

Ovarian cancer accounts for 4% of all cancers in women. An estimated 20,650 new cases of ovarian cancer are expected to be diagnosed in the United States during 2008, according to the latest statistics.