What Is Ovarian Cancer?

This content has been reviewed and approved by

Maurie Markman, MD
Vice President, Clinical Research
MD Anderson Cancer Center
University of Texas

If you've received a diagnosis of cancer in one or both of your ovaries, you should know that you are not alone. Ovarian cancer was the eighth most commonly diagnosed form of cancer in women in the United States in 2010. It will account for an estimated 3 percent of all new cancer cases in women, according to estimates from the American Cancer Society (ACS). One out of approximately every 58 women in the United States will have ovarian cancer sometime during their lives.

The ovaries are small (about the size of an almond) female reproductive organs that reside in the pelvis. There are two ovaries, one on each side of the uterus, or womb.

The ovaries produce the female hormones: estrogen and progesterone. Estrogen and progesterone control the development of female body characteristics (i.e., breasts, body shape, and body hair) and regulate the menstrual cycle and pregnancy. The ovaries also store all of the egg cells, a vital part of human reproduction.

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Some ovarian tumors are benign (not cancerous). Malignant (cancerous) ovarian tumors can originate from cells found in an ovary. There are three types of ovarian tumors named for the tissue in which they are found:

• Epithelial cell - cells that cover the surface of the ovary
• Germ cell - cells that form the eggs in the ovary
• Stromal cell - cells that form the ovary and produce female hormones

The majority of ovarian cancers develop from cells in the lining of the ovary. Most of these tumors are benign (noncancerous). However, epithelial ovarian cancer accounts for 85 percent to 90 percent of ovarian cancer cases.