Risk of epithelial ovarian cancer in relation to benign ovarian conditions and ovarian surgery

Some forms of ovarian neoplasms may be preventable through the removal of precursor lesions. We assessed the risk associated with a prior diagnosis of, and ovarian surgery following, ovarian cysts and endometriosis, with a focus on characterizing risk among tumor subgroups. Information was collected during in-person interviews with 812 women with ovarian cancer diagnosed in western Washington State from 2002 to 2005 and 1,313 population-based controls. Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs). The risk of a borderline mucinous ovarian tumor associated with a history of an ovarian cyst was increased (OR=1.7, 95% CI: 1.0-2.8), but did not vary notably according to receipt of subsequent ovarian surgery. While risk of invasive epithelial ovarian cancer was slightly increased among women with a cyst who had no subsequent ovarian surgery, it was reduced when a cyst diagnosis was followed by surgery (OR = 0.6, 95% CI: 0.4-0.9). This reduction in risk was most evident for serous invasive tumors. Women with a history of endometriosis had a threefold increased risk of endometrioid and clear cell invasive tumors, with a lesser risk increase among women who underwent subsequent ovarian surgery. Our results suggest differences in the relation of ovarian cysts and endometriosis with risk of specific subtypes of ovarian cancer as well as the possibility that ovarian surgery in women with these conditions may lower the risk of invasive disease.