Overview

Ovarian cancer begins in a woman's ovaries. The ovaries are the glands containing the germ cells or eggs. They are part of a woman's reproductive system and every woman has two ovaries, one located on each side of the uterus. They are almond shaped and about one and a half inches long. Every month, during ovulation, an egg is released from an ovary and travels to the uterus through a structure called the fallopian tube.

Ovaries are the primary source of women's sex hormones, estrogen and progesterone. These hormones influence breast growth, body shape, and body hair, and regulate the menstrual cycle and pregnancy. During menopause, the ovaries stop releasing eggs and producing sex hormones.

Ovarian cancer begins when normal cells in an ovary begin to change and grow uncontrollably, forming a mass called a tumor. A tumor can be benign (noncancerous) or malignant (cancerous, meaning it can spread to other parts of the body). Removing the ovary or the part of the ovary where the tumor is located can treat a noncancerous ovarian tumor. An ovarian cyst, which forms on the surface of the ovary, is different than a noncancerous tumor and usually goes away without treatment. Ovarian cysts are not cancerous.

There are three types of ovarian cancer:

Epithelial carcinoma. Epithelial carcinoma makes up 85% to 90% of ovarian cancers. This type of cancer begins in cells on the outer surface of the ovary.

Germ cell tumor. This uncommon type of ovarian cancer develops in the egg-producing cells of the ovaries. This type of tumor is more common for women ages 10 to 29.

Stromal tumor. This rare form of ovarian cancer develops in the connective tissue cells that hold the ovaries together and make female hormones.

Statistics

In 2009, an estimated 21,550 women in the United States will be diagnosed with ovarian cancer. It is estimated that 14,600 deaths from this disease will occur this year. Ovarian cancer accounts for nearly 3% of all cancers among women. It is the ninth most common cancer and fifth most common cause of cancer death in women.

The one-year relative survival rate (percentage of women who survive at least one year after the cancer is detected, excluding those who die from other diseases) of women with ovarian cancer is 75%. The five-year relative survival rate (percentage of women who survive at least five years after the cancer is detected, excluding those who die from other diseases) is 46%. If the cancer is diagnosed and treated before it has spread outside the ovaries, the five-year survival rate is 93%. If the cancer has spread to the surrounding organs or tissue (local spread), the five-year relative survival rate is 71%. If the cancer has spread to parts of the body far away from the ovary (distant spread), the five-year relative survival rate is 31%.

Cancer survival statistics should be interpreted with caution. These estimates are based on data from thousands of cases of this type of cancer in the United States each year, but the actual risk for a particular individual may differ. It is not possible to tell a woman how long she will live with ovarian cancer. Because survival statistics are often measured in multi-year intervals, they may not represent advances made in the treatment or diagnosis of this cancer.

Statistics adapted from the American Cancer Society's publication, Cancer Facts & Figures 2009.

Find out more about basic cancer terms used in this section.