Abstract: Objective To explore the independent predictors for disease-specific survival (DSS) rate in patients with stage N_1-3 testicular seminoma (TS), and establish a nomogram to predict individual 5-year DSS. MethodsThe data of N_1-3 TS patients registered in the SEER database of National Cancer Institute (USA) from January 2004 to December 2015 were retrospectively analyzed. The 5-year overall survival (OS) rate and DSS rate were calculated using Kaplan-Meier method and the differences among different subgroups were assessed using log-rank test. Besides, the independent predictors of DSS were defined using multivariate Cox regression analysis, and nomogram was drawn using R software. Furthermore, the predictive performance of the nomogram was internally validated using the C-index and calibration plot. Results TNM stage ⅢA (HR=5.604, 95%CI: 1.252-25.083, P=0.024), ⅢB (HR=6.710, 95%CI: 1.923-23.410, P=0.003) and ⅢC (HR=13.189, 95%CI: 3.916-44.420, P＜0.001), age at diagnosis ≥45 years old (HR=3.575, 95%CI: 2.014-6.344, P＜0.001), and patients without spouse (HR=2.346, 95%CI: 1.406-3.914, P=0.001) were identified as independent risk factors for DSS. On internal validation, the predictive accuracy of our nomogram was 0.751 (C-index: 0.751, 95%CI: 0.694-0.808). Besides, the calibration plot showed that the predicted survival outcomes were highly consistent with the actual survival outcomes. Conclusion The study confirms that age at diagnosis ≥45 years old, TNM stage ≥ⅢA and patients without spouse are the independent risk factors for DSS in TS patients with stage N_1-3, and the nomogram for predicting individual 5-year DSS is established.

Key words: Seminoma, Lymphatic metastasis, Prognosis, Nomogram