 The risk of developing ovarian cancer appears to jump about fourfold for women who have endometriosis. That's according to a new study. Endometriosis is when tissue similar to the lining of the uterus grows outside of the uterus itself. Itself already shows links to ovarian cancer, but the new study found even higher cancer risk for some subtypes of the condition. For example, women with deep infiltrating endometriosis, ovarian endometriomas, or both,