Development and validation of a prognostic model incorporating tumor thrombus grading for nonmetastatic clear cell renal cell carcinoma with tumor thrombus: A multicohort study.

There is significant variability with respect to the prognosis of nonmetastatic clear cell renal cell carcinoma (ccRCC) patients with venous tumor thrombus (VTT). By applying multiregion whole-exome sequencing on normal-tumor-thrombus-metastasis quadruples from 33 ccRCC patients, we showed that metastases were mainly seeded by VTT (81.8%) rather than primary tumors (PTs). A total of 706 nonmetastatic ccRCC patients with VTT from three independent cohorts were included in this study. C-index analysis revealed that pathological grading of VTT outperformed other indicators in risk assessment (OS: 0.663 versus 0.501-0.610, 0.667 versus 0.544-0.651, and 0.719 versus 0.511-0.700 for Training, China-Validation, and Poland-Validation cohorts, respectively). We constructed a risk predicting model, TT-GPS score, based on four independent variables: VTT height, VTT grading, perinephric fat invasion, and sarcomatoid differentiation in PT. The TT-GPS score displayed better discriminatory ability (OS, c-index: 0.706-0.840, AUC: 0.788-0.874; DFS, c-index: 0.691-0.717, AUC: 0.771-0.789) than previously reported models in risk assessment. In conclusion, we identified for the first-time pathological grading of VTT as an unheeded prognostic factor. By incorporating VTT grading, the TT-GPS score is a promising prognostic tool in predicting the survival of nonmetastatic ccRCC patients with VTT.