Ovarian cancer is a disease in which cancer cells grow in the ovaries. The ovaries are a pair of organs in the female pelvis that produce eggs and female hormones.

Cancerous Mass in the Left Ovary
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Cancer occurs when cells in the body (in this case ovarian cells) divide without control or order. Normally, cells divide in a regulated manner. If cells keep dividing uncontrollably when new cells are not needed, a mass of tissue forms, called a growth or tumor. The term cancer refers to malignant tumors, which can invade nearby tissues and can spread to other parts of the body. A benign tumor does not spread.

There are several cancers and several more benign tumors that may occur in the ovaries. Most cancers are called epithelial cell tumors, which are the focus of this article. These tumors may grow to a considerable size before they cause severe symptoms. Malignant ovarian tumors may spread by shedding cells into the peritoneal cavity, which then causes metastasis throughout the abdomen—making these tumors difficult to treat. Early detection is very important to help prevent the cancer from spreading.

A specific cause of ovarian cancer has not been discovered, but certain risk factors are associated with the disease. Having a family history of ovarian cancer puts you at much higher risk. Your reproductive (female) history may also affect your risk, such as the number of times you have been pregnant and when you started and stopped your periods. In addition, there may be some environmental factors, but these are not definite.

Ovarian cancer is the fifth leading cause of cancer deaths among US women and the leading cause of death due to cancer of the gynecologic organs.