About 22,000 women were diagnosed with ovarian cancer in the United States in 2010. The overall prognosis of patients with early stage ovarian cancer is excellent with a five year survival rate of over 90 percent. Most cases of ovarian cancer are however diagnosed at advanced stages with disease outside of the ovary and the pelvis. The overall five-years survival for the advanced stages is about 45 percent which is still significantly better than the prognosis for other intra-abdominal cancers that originate for example from the bowel or stomach.
Ovarian cancer begins in a woman’s ovaries which are part of the female reproductive system and are located on each side of the uterus in the pelvis. They are almond shaped and about one and a half inches long. 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. Every month, during ovulation, an egg is released from an ovary and travels to the uterus through a structure called the fallopian tube. During menopause, the ovaries stop releasing eggs and producing sex hormones.
The ovaries contain a variety of different cell types, including surface or epithelial cells, germ cells and stromal cells. All these different cell types can develop into very different forms of ovarian cancer, but the most frequent origin of ovarian cancer is the cells on the surface of the ovary, also called epithelial cells. The following information is therefore mostly related to epithelial ovarian cancer.
Despite a lot of research over the last decades, it is still unknown how ovarian cancer develops. Ovarian cancer begins when cells in an ovary begin to change, grow uncontrollably, and eventually form a tumor. Tumors can be benign (noncancerous) or malignant (cancerous). Removing the affected ovary or the part of the ovary where the tumor is located can successfully treat benign ovarian tumors.