Endometriosis is a chronic and often progressive disease that develops when endometrial tissue, which normally lines the inner surface of the uterus, grows outside of the uterus. These implants occur most frequently in the pelvic region and on the reproductive organs but can appear in other areas, such as the bladder. In spite of the high prevalence of endometriosis in women the world over, researchers have been unable to determine its cause. Endometriosis can cause pain and scarring, and it is believed that 20 percent to 40 percent of women diagnosed with this chronic disease are infertile (National Cancer Institute).Researchers have hypothesized that the most likely link between endometriosis and ovarian cancer is the association between endometriosis and infertility. It is well established that ovarian cancer risk is reduced with each pregnancy. Consequently, women who do not bear children, whether by choice or due to infertility issues, are believed to be at greater risk for ovarian cancer (The Gynecologic Sourcebook, Third Edition).