Nomogram for predicting the prognosis of metastatic thymic epithelial tumors

Background: The majority of patients diagnosed with thymic epithelial tumors (TETs) are often at an advanced stage that precludes cure. This study aimed to develop a nomogram to predict the prognosis of metastatic TETs. Methods: Patients diagnosed as metastatic TETs in Sun Yat-sen University Cancer Center from July 2000 to November 2021 were retrospectively reviewed. A nomogram was developed to predict the prognosis of metastatic TETs. The performance of the nomogram was assessed by the concordance index (C-index), calibration curves, and decision curve analysis curves. Based on the nomogram scores, patients were divided into different prognostic groups. Results: A total of 254 patients were enrolled. The median overall survival (OS) was 53.03 months [95% confidence interval (CI): 40.56-65.51]. Univariate and multivariate analyses showed that World Health Organization (WHO) histologic classification type C, Masaoka-Koga stage IVb, Karnofsky performance status (KPS) score 70-80, and baseline serum albumin level <40 g/L were independent poor prognostic factors of OS. These factors were then taken into the development of nomogram model. The C-index was 0.68 (95% CI: 0.59-0.79), indicating good performance. The risk groups were categorized by nomogram scores with a threshold at 112 score. The median OS in the high-risk group was much shorter than that of the low-risk group [28.60 versus 74.17 months, hazard ratio (HR): 2.44; 95% CI: 1.65-3.62; P<0.001]. Conclusions: WHO histologic classification, Masaoka-Koga stage, KPS score, and baseline serum albumin level were identified as independent prognostic factors of OS in metastatic TETs. This study developed a nomogram model effectively predicting the prognosis of metastatic TETs.