Ovarian cancer is a growth of abnormal malignant cells that begins in the ovaries (women’s reproductive glands that produce eggs), fallopian tubes (and then migrates to the ovaries), or the peritoneum. While some cancers may originate at additional sites and then spread to the ovary or ovaries, this is not considered ovarian cancer.
Ovarian tumors can be benign (noncancerous) or malignant (cancerous). Although abnormal, cells of benign tumors do not metastasize (spread to other parts of the body). Malignant cancer cells in the ovaries can metastasize in two ways:
- directly to other organs in the pelvis and abdomen (the more common way)
- through the bloodstream or lymph nodes to other parts of the body
While the causes of ovarian cancer are unknown, some theories exist:
- Genetic errors may occur because of the repeated “wear and tear” of the monthly release of an egg.
- Increased hormone levels before and during ovulation may stimulate the growth of abnormal cells.
- Fallopian tubes are the site of origin in at least some ovarian cancers.
Ovarian cysts are different than ovarian tumors, and can be fairly common—ovarian cysts are fluid-filled while ovarian tumors are solid masses. Most ovarian cysts are not harmful, don’t cause symptoms and are not indicative of risk for future ovarian cancer, though some complex ovarian cysts may raise the risk. Learn more about ovarian cysts.