Development and internal validation of nomograms for the prediction of postoperative survival of patients with grade 4 renal cell carcinoma (RCC)

BACKGROUND: To develop successful prognostic models for grade 4 renal cell carcinoma (RCC) following partial nephrectomy and radical nephrectomy. METHODS: The nomograms were established based on a retrospective study of 135 patients who underwent partial and radical nephrectomy for grade 4 RCC at the Department of Urology, Peking University First Hospital from January 2013 to October 2018. The predictive performance of the nomograms was assessed by the calibration plot and C-index. The results were validated using bootstrap resampling. RESULTS: Aspartate transaminase (AST), the maximum diameter of tumor (cutoff value =7 cm), lymph node metastasis, and the International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) risk group were independent factors for determining the overall survival (OS) and cancer-specific survival (CSS) in multivariate analysis. AST, the maximum diameter of the tumor (cutoff value =7 cm), and lymph node metastasis were found to be independent variables for progression-free survival (PFS) in multivariate analysis. These variables were used for the studies to establish nomograms. All calibration plots revealed excellent predictive accuracy of the models. The C-indexes of the nomograms for predicting OS, CSS and PFS were 0.729 (95% CI, 0.659–0.799), 0.725 (95% CI, 0.654–0.796) and 0.702 (95% CI, 0.626–0.778), respectively. Moreover, the recurrence rate was not associated with open or laparoscopic radical nephrectomy in our cohort (P=0.126). CONCLUSIONS: We have developed easy-to-use models that are internally validated to predict postoperative 1-, 3-, and 5-year OS, CSS, and PFS rates of grade 4 RCC patients. The new models could aid in identifying high-risk patients, making postoperative therapeutic and follow-up strategies as well as predicting patients’ survival after externally validated. Besides, our study shows that the recurrence rate is not associated with open or laparoscopic radical nephrectomy.