Ovarian cancers begin 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 (ova); and
- Stromal tumors develop from tissue cells that hold the ovary together and produce the female hormones estrogen and progesterone.
Most of these tumors are benign and never spread beyond the ovary. However, malignant or low malignant potential ovarian tumors can spread to other parts of the body and can be fatal.
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. There were approximately 22,000 new cases of ovarian cancer and an estimated 14,200 people died of this disease in the United States in 2014. Overall, the five-year survival rate is 44%. If the cancer is detected early, at the localized stage when the cancer is only in the part of the body where it started, the five-year survival rate is 92%. However, if the cancer is found in the regional and distant stages, when the cancer has spread, the five-year survival rate is 27%. The majority of cases (61%) are detected at the distant stage. Only 15% are detected at the localized stage. No treatment is available for patients with refractory or resistant metastatic ovarian cancer.