Histologic Subtype, Tumor Grade, Tumor Size, and Race Can Accurately Predict the Probability of Synchronous Metastases in T2 Renal Cell Carcinoma

Background: We investigated the association between synchronous metastases (SMs), histologic subtype (HS), tumor size (TS), and tumor grade (TG) in surgically treated stage T2 renal cell carcinoma (RCC). Materials and methods: Within the Surveillance, Epidemiology, and End Results database (2005-2015), 8344 patients with T2 RCC who had undergone radical nephrectomy were identified. The SM rates were tabulated according to the HS, TG, and TS and tested in multivariable logistic regression models. Results: According to the HS, the average SM rates were 0%, 1.4%, 4.6%, 6.4%, 12.7%, 20.0%, and 32.7% for multilocular cystic, chromophobe, papillary, TG 1-2 clear cell, TG 3-4 clear cell, collecting duct, and sarcomatoid dedifferentiation RCC, respectively. In multivariable logistic regression models predicting for SMs, HS represented the strongest predictor, followed by TG, TS, and race. When combined, HS, TG, TS, and race predicted for SMs with 70.2% accuracy compared with 62.5% with HS, 60.2% with TG, 57.8% with TS, and 53.0% with race alone. Lung only was the most common metastatic site (43.6%), followed by bone only (27.6%), liver only (4.4%), and brain only (4.4%). Of all the patients with SMs, 78.9% had a single metastatic site. Conclusions: The SM rates showed very wide variation according to the HS, TG, and TS. When HS was combined with TG, TS, and race, SMs could be accurately predicted in individual patients better than with TS alone. Thus, renal mass biopsy-derived HS and TG could improve the prediction of SMs compared with using TS alone.