Diagnostic Performance of the International Ovarian Tumor Analysis Simple Rules with CA125 in Differentiating between Benign and Malignant Adnexal Masses

Abstract

Objectives: To evaluate the diagnostic performance of the International Ovarian Tumor Analysis (IOTA) simple rules in combination with serum tumor marker Cancer Antigen 125 (CA125). Materials and Methods: This secondary analysis was based on a previous prospective diagnostic single-center study conducted at Siriraj Hospital, Thailand, between May 1, 2018, and May 31, 2019. Gynecological patients scheduled for an elective adnexal surgery at Siriraj Hospital were recruited. Preoperative ultrasound was performed within 120 days before surgery. The assessment included IOTA simple rules, IOTA simple rules with subjective assessment, and IOTA simple rules with CA125. The sensitivity, specificity, positive predictive value, negative predictive value and area under the receiver operating characteristic curve (AUC) were assessed. Results: A total of 357 patients from the original study cohort were included, and all were found eligible. The IOTA simple rules were applicable in 316 cases (88.5%), and achieved an AUC of 0.938 (95% CI 0.897-0.979). The IOTA simple rules along with subjective assessment demonstrated a similar AUC, 0.933 (95% CI 0.892-0.975). Integrating CA125 with the IOTA simple rules reduced the AUC to 0.825 (95% CI 0.776–0.875). When CA125 was applied exclusively to the inconclusive group, the AUC was 0.909 (95% CI 0.866–0.953). The optimal cutoff value of CA125 calculated from our cohort was 115 U/ml. Conclusion: The IOTA simple rules are an excellent model for differentiating benign and malignant adnexal masses. Selective use of CA125 or subjective assessment in inconclusive cases can support decision-making.