The Comparison of Three Predictive Indexes to Discriminate Malignant Ovarian Tumors from Benign Ovarian Endometrioma: The Characteristics and Efficacy

Abstract

This study aimed to evaluate the prediction efficacy of malignant transformation of ovarian endometrioma (OE) using the Copenhagen Index (CPH-I), the risk of ovarian malignancy algorithm (ROMA), and the R2 predictive index. This retrospective study was conducted at the Department of Gynecology, Nara Medical University Hospital, from January 2008 to July 2021. A total of 171 patients were included in the study. In the current study, cases were divided into three cohorts: pre-menopausal, post-menopausal, and a combined cohort. Patients with benign ovarian tumor mainly received laparoscopic surgery, and patients with suspected malignant tumors underwent laparotomy. Information from a review chart of the patients’ medical records was collected. In the combined cohort, a multivariate analysis confirmed that the ROMA index, the R2 predictive index, and tumor laterality were extracted as independent factors for predicting malignant tumors (hazard ratio (HR): 222.14, 95% confidence interval (CI): 22.27−2215.50, p < 0.001; HR: 9.80, 95% CI: 2.90−33.13, p < 0.001; HR: 0.15, 95% CI: 0.03−0.75, p = 0.021, respectively). In the pre-menopausal cohort, a multivariate analysis confirmed that the CPH index and the R2 predictive index were extracted as independent factors for predicting malignant tumors (HR: 6.45, 95% CI: 1.47−28.22, p = 0.013; HR: 31.19, 95% CI: 8.48−114.74, p < 0.001, respectively). Moreover, the R2 predictive index was only extracted as an independent factor for predicting borderline tumors (HR: 45.00, 95% CI: 7.43−272.52, p < 0.001) in the combined cohort. In pre-menopausal cases or borderline cases, the R2 predictive index is useful; while, in post-menopausal cases, the ROMA index is better than the other indexes.

Keywords: CPH index; R2 predictive index; ROMA index; borderline ovarian tumor; endometriosis associated ovarian cancer; malignant ovarian tumor; ovarian endometrioma.

Figure 1

The ROC curves of each predictive index in the combined cohort. The row indicates each predictive index and the column indicates each cohort. The R2 predictive index showed a high AUC in the pre-menopausal cohort; on the contrary, the ROMA and CPH indexes showed high AUCs in post-menopausal cohort.

Figure 2

The ROC curves of other factors. The row indicates each factor, and the column indicates each cohort.

Figure 3

The ROC curves of each tumor marker. CEA showed a higher AUC than HE4 and CA125 in the pre-menopausal cohort; however, in the post-menopausal cohort HE4 and CA125 increased their AUC in the post-menopausal cohort.

Figure 4

To discriminate borderline tumors from ovarian endometriosis, the R2 predictive index could be the most effective tool. ** p < 0.01 vs. others., *** p < 0.001 vs. others. The circles represent outliers. There were only two borderline cases in post-menopausal cohort (lower right).