Incidence and Associated Risk Factors of Patients with Malignant Transformation Arising in Mature Cystic Teratoma of the Ovary in Rajavithi Hospital

Abstract

Objectives: To review the incidence and evaluate risk factors associated with malignant transformation in mature cystic teratoma (MCT) of the ovary.Methods: A retrospective medical record review for 571 patients diagnosed as ovarian MCT who were treated at Rajavithi Hospital from January 2005 to June 2017 was performed. The demographics data, preoperative investigations, pathological findings, adjuvant treatments, and follow-up outcomes were obtained and analyzed. Results: Forty patients with malignant transformation in MCT were detected over a period of 12 years. The incidence rate was 7% of all MCT. Squamous cell carcinoma was the most common histologic type (45%) and the most of them were stage I (80%). Patients with malignant transformation were significantly older than those benign MCT (48.4 years vs 37.5 years, p 10 cm. (OR 6.68; 95%CI, 2.39-18.65), solid part from ultrasound findings (OR 5.30; 95%CI, 1.63-17.24), and RMI score ≥200 (OR 8.69; 95%CI, 1.68-44.89) were a significant predictor of malignant transformation arising in MCT. Performance validation with a cut-off level of RMI ≥200 showed the AUC was 0.879, with 47.5% sensitivity, 98.4% specificity, 82.6 % positive predictive value, and 92.2% negative predictive value, respectively. Conclusion: Early detection and complete surgical resection of ovarian cancer are important for a long-term survival. Large tumor size and solid part from ultrasound finding were associated with malignant transformation in MCT. Additionally, calculating RMI score might be a useful diagnostic tool to detect malignancy in this setting, and adequate staging surgery should also be considered.