Influence of tumor size on oncological outcomes of pathological T3aN0M0 renal cell carcinoma treated by radical nephrectomy

Objective To evaluate the prognostic significance of tumor size in pathological T3aN0M0 renal cell carcinoma (RCC) treated by radical nephrectomy. Materials and methods Patients who underwent radical nephrectomy for sporadic RCC with pathological T3aN0M0 RCC at our institution between January 2006 and June 2015 were identified. The entire cohort was divided into two groups according to the cutoff of tumor size obtained from receiver operating characteristic (ROC) curve. Clinicopathological variables were retrospectively collected and compared. Kaplan-Meier analysis and multivariate Cox regression were conducted to evaluate the effect of tumor size on survival outcomes. Results 163 pT3aNOMO RCC patients were included with a median follow-up period of 31 months. The optimal cutoff for tumor size was 7 cm according to the ROC curve. 90 cases (55.2%) presented tumors which measured 7 cm or less, and 73 cases (44.8%) showed tumor size greater than 7 cm. Patients with larger tumors tended to exhibit higher rates of symptoms and higher Fuhrman grades; they also indicated more necrosis features, and were more likely to invade the collecting system and renal vein. Compared with patients who exhibited tumor size of <= 7 cm, those with tumor size>7 cm were associated with shorter estimated five-year cancer-specific survival (CSS, 46.6% versus 75.0%, P=0.003) and five-year recurrence-free survival (RFS, 35.6% versus 62.7%, P = 0.011). Multivariate Cox analysis revealed that tumor size was retained as an independent factor for CSS (HR = 2.506, 95% CI 1.169-5.373, P=0.018). Conclusions The tumor size significantly affected the survival outcomes of pT3aN0M0 RCC treated by radical nephrectomy, and a cutoff size of 7 cm can help enhance the prognostic discrimination. Thus, the tumor size may be considered in the future TNM classification of stage pT3a.