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About the ovaries
Ovarian cancer begins in a woman's ovaries. The ovaries are glands that contain the germ cells or eggs. Every woman has two ovaries as part of her reproductive system, 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 a woman’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.
About ovarian cancer
Ovarian cancer begins when normal cells in an ovary 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. An ovarian cyst is 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.
Find out more about basic cancer terms used in this section.
Looking for More of an Overview?
If you would like additional introductory information, explore these related items on Cancer.Net:
- ASCO Answers Fact Sheet: Read a one-page fact sheet (available in PDF) that offers an easy-to-print introduction for this type of cancer.
- Cancer.Net En Español: Read about ovarian cancer in Spanish. Infórmase sobre cáncer de ovario en español.
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