Objective: We assessed whether asymptomatic ovarian abnormalities detected on ultrasonography in postmenopausal women are precursors to ovarian cancer.
Study design: We compared the transvaginal ultrasonographic findings from the initial examination of 20,000 postmenopausal women enrolled to date in an ongoing randomized trial of cancer screening with data on the established risk factors for ovarian cancer obtained from self-administered questionnaires. We distinguished cysts with the suggestive characteristic(s) of a septum, a solid component, or an irregular or thick wall ("complex cysts") from simple sonolucent cysts with none of those features.
Results: High parity, a strong ovarian cancer protective factor, was negatively associated with complex cysts (odds ratio for > or =5 births vs no births, 0.72; 95% confidence interval, 0.53-0.97), but long-term oral contraceptive use, another strong ovarian cancer protective factor, was not associated with complex cysts (odds ratio, 0.96; 95% confidence interval, 0.76-1.20). A family history of ovarian cancer or multiple breast cancers, a strong risk factor for cancer, was not associated with complex cysts (odds ratio, 0.99; 95% confidence interval, 0.68-1.44). Other abnormalities found on ultrasonography (including simple cysts, bilateral cysts, or all abnormalities combined) also did not share the established risk factors for ovarian malignancy. We did not identify any combination of features of abnormalities (septum, echogenicity, size, or papillary projections) that manifested the cancer risk factor profile.
Conclusions: Although a very small proportion of the clinically silent ovarian abnormalities found on ultrasonography are determined to be ovarian cancers, the remaining complex cysts and other clinically suspicious abnormalities do not appear to be the immediate precursors of ovarian cancer. The eventual identification of such precursors will yield opportunities for earlier diagnosis, screening of high-risk groups, and better understanding of the cause of this often lethal malignancy.