Optimal size cutoff point for prognostic stratification of localized renal cell carcinoma

Purpose: The purpose of this study was to evaluate the validity of the cutoff size for a localized renal cell carcinoma (RCC) by assessing the survival of RCC patients according to a series of alternative size cutoff values. Materials and Methods: The outcomes of 147 patients with localized RCC, treated by radical nephrectomy at our institution, between 1984 and 2004, were retrospectively evaluated. The mean follow-up period was 54.9±32.5 months. The survival of patients with tumors smaller than a specified size cutoff was compared with that of tumors larger than the cutoff, and the most discriminating cutoff identified. Results: 114 and 33 patients were pT1 (77.6%) and pT2 (22.4%), respectively. There were 10 recurrences (8.8%) and 6 deaths (5.3%) in the pT1 group, and 8 recurrences (24.2%) and 8 deaths (24.2%) in the pT2 group. The differences in survival were maximized when the tumor size cutoff point was 7cm (cancer-specific survival rate: 92.0% vs. 71.5% p=0.0003, disease-free survival rate: 88.5% vs. 69.1% p=0.0092). The next significant difference was observed with a cutoff of 4cm (cancer-specific survival rate: 96.0% vs. 83.7% p=0.0467, disease-free survival rate: 96.0% vs. 78.8% p=0.0121). Conclusions: Tumor size is an important prognostic factor in patients with an organ confined RCC. The established cutoff point of 7cm provided reasonable prognostic differences. A 4cm cutoff point is also feasible for separating groups with different survivals after a nephrectomy. Hence, the T1a/1b/ T2 classification system is practical for the division of localized RCC.