Risk of malignancy index is not sensitive in detecting non-epithelial ovarian cancer and borderline ovarian tumor.

ObjectiveTo determine the value of risk of malignancy index in detection of ovarian cancer and referral of adnexal masses.Material and methodPatients scheduled for surgery due to adnexal mass between May 2008 and August 2009 were prospectively included in the study. Risk of malignancy index (RMI) was calculated for each patient with a published formula (RMI=Ultrasonic score X menopausal status X Ca-125 (IU/ml) level). RMI >200 was accepted as positive for malignancy and the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of RMI in detecting malignant cases were calculated.ResultsOne hundred consecutive patients of whom 80 (80%) had benign ovarian cyst, 4 (4%) had borderline lesion and 16 (16%) had invasive ovarian cancer were included in the study. Forty-five percent (9/20) of malignant cases were epithelial ovarian cancer, 20% (4/20) were borderline ovarian tumor, 30% (6/20) were non-epithelial ovarian tumor and 5% (1/20) was a metastasis from the appendix. All the cases with epithelial ovarian cancer had positive RMI but only 1 of 4 borderline lesions, 2 of 6 non-epithelial ovarian cancers had positive RMI. The sensitivity of RMI was 60%, specificity was 88.8%, PPV was 57.1% and NPV was 89.9% for all cases. When the cancer cases other than epithelial ovarian cancers were excluded, the sensitivity, specificity, PPV and NPV of RMI was 76.92%, 88.75%, 52.63% and 95.95% respectively.ConclusionsRMI is not adequate in detecting malignant cases in a population with high non-epithelial ovarian cancer and borderline ovarian tumor prevalence.