Risk of Malignancy Index in the Evaluation of Patients With Adnexal Masses

Objective: To determine if the risk of malignancy index (RMI) can distinguish between benign and malignant adnexal masses in a population of women referred to a department of gynaecologic oncology for surgical resection of an adnexal mass. Methods: We performed a retrospective review of the medical of charts of 259 consecutive patients. Ninety-six charts did not have data available to calculate the RMI, leaving a total of 163 for review. Three definitions of RMI were compared; each incorporated menopausal status of the patient, ultrasound characteristics of the adnexal mass, and serum CA-125 level. Results: Of the masses resected, 105 were benign and 58 were malignant. The area under the ROC curve for all three definitions of RMI was 0.87. Using a cut-off of 120, the first RMI definition (RMI 1) had a sensitivity of 72% and a specificity of 87%; the second (RMI 2) had a sensitivity of 76% and a specificity of 81%; and the third (RMI 3) had a sensitivity of 74% and a specificity of 84%. These results are generally in agreement with published values. Conclusion: We have validated the use of RMI to predict the risk of malignancy in a Nova Scotia population of women with adnexal masses. This will aid in more selective referral of patients to specialized oncology centres for cancer surgery, allowing for appropriate management of health care resources and optimization of treatment for women with gynaecological malignancies.