To develop and comprehensively validate a simplified and easy-to-use prediction tool for the risk of metastatic recurrence after surgery for non-metastatic renal cell carcinoma with an associated venous tumor thrombus.

We evaluated 532 patients who underwent nephrectomy and venous thrombectomy for M0 RCC from 2000 to 2021. Clinicopathological and surgical data were analyzed. A 70-30 split (test and train cohort, respectively) and the least absolute shrinkage and selection operation regression (LASSO) model were used to select variables independently associated with recurrence. We developed a nomogram and validated it both internally and externally with 2 separate institutional datasets. Additionally, we performed decision curve analysis for the use of adjuvant Pembrolizumab.

We included 278 (52.3%), 66 (12.4%), 116 (21.8%), 35 (6.6%), and 37 (7.0%) patients with level zero through 4 tumor thrombi, respectively. Overall, estimated 5-year metastasis-free survival (MFS) was 41.3%. The resulting nomogram was composed of thrombus level, tumor necrosis, sarcomatoid features, and pN stage. AUC at 5 years was 0.74 in both our internal test and train cohorts, and 0.71 and 0.68 in 2 external cohorts. On decision curve analytics, our nomogram adds net benefit at a threshold probability between 0.33 and 0.80.

We provide an internally and externally validated risk calculator for 5-year MFS following radical nephrectomy with tumor thrombectomy. This prognostic tool may be used to guide selection for adjuvant therapies and to assist in clinical trial design.