Development and validation of a prognostic model predicting the prognosis of surgically treated non-clear cell renal cell carcinoma patients with tumor thrombus

Background Accurate prediction of clinical outcomes in non-clear cell renal cell carcinoma with tumor thrombus (nccRCC-TT) patients is crucial for counseling, follow-up planning, and selecting appropriate systemic therapy. We aimed to investigate independent prognostic factors for overall survival (OS) and cancer-specific survival (CSS) in nccRCC-TT patients after surgical resection and construct a nomogram predicting the 1-, 3-, and 5-year survival for these patients. Methods This was a retrospective analysis of data from the Surveillance, Epidemiology, and End Results (SEER) database (2010–2020) and the China REMEMBER database with nccRCC-TT patients. NccRCC-TT patients from the SEER database were randomly divided into training and internal validation sets. Multivariable nomogram models were built and validated to predict OS and CSS. Scores based on the nomograms were used to conduct risk stratification. The performance of these nomograms was then compared with the American Joint Committee on Cancer (AJCC) TNM staging system. Results A total of 809 patients participated, with a training set ( n  = 514), an internal validation set ( n  = 216), and an external validation set ( n  = 79). Median follow-up times for OS were 51, 47, and 28 months in the three sets, respectively. The nomogram integrated seven risk factors affecting survival (advanced age, left side, histology, positive lymph nodes, distant metastasis, renal sinus/perirenal fat invasion, and sarcomatoid/rhabdoid differentiation) to predict OS and CSS at 1-, 3-, and 5-years. Outperforming the AJCC staging system, the nomogram achieved a C-index of 0.774 (95% CI, 0.727–0.821) for OS and 0.787 (95% CI, 0.736–0.838) for CSS in the internal validation set. Both OS and CSS significantly differed between subgroups with low, moderate, and high risk (all P  < 0.001). Conclusions Pathological combined histological features are crucial predictors of prognosis in nccRCC-TT patients. We developed a tool to improve patient counseling and guide decision-making on other therapies in addition to surgery for patients with nccRCC-TT. Risk stratification based on our nomograms provides postoperative consultation and patient selection for treatment strategies.