Ovarian cancer begins in the ovaries, which are made up of 3 main kinds of cells. Each type of cell can develop into a different type of tumor:

  • The most common type, epithelial tumors, develops from the cells that cover the outer surface of the ovary.
  • Germ cell tumors develop from the cells that produce the eggs.
  • Stromal tumors develop from tissue cells that hold the ovary together and produce the female hormones estrogen and progesterone.

Ovarian, fallopian tube, or primary peritoneal cancer have a lot in common and are treated following similar approaches. Epithelial ovarian cancer is the leading cause of death from gynecologic cancer in the United States and the country’s fifth most common cause of cancer mortality in women. This cancer mainly develops in older women.