External validation of an international multicenter study to predict survival in Korean patients with pT2N0M0 renal cell carcinoma.

Objectives: To determine whether a tumor size cut-off can improve the prognostic accuracy of the current tumor-node-metastasis staging system in Korean patients with pT2 renal cell carcinoma (RCC).

Methods: We identified 819 patients treated with radical nephrectomy for clinical RCC between 1995 and 2005. The study included 102 patients of pT2N0M0 RCC.

Results: When 5-year survival rates were calculated using 0.5-cm increments between 7.5 and 12.5 cm, none of the cut-offs provided a significant difference in 5-year overall and cancer-specific survival. Cut-offs of 9.5 and 10.0 cm provided significant difference in 5-year progression-free survival (log-rank score 4.37, P = .037; log-rank score 6.75, P = .009, respectively). However, a 10.5-cm cut-off provided the greatest difference in 5-year progression-free survival (log-rank score 7.19; P = .007). Multivariate Cox proportional hazards model analysis using the variables of age, sex, American Society of Anesthesiologists score, tumor side, histologic type, tumor grade, and tumor diameters showed that tumor diameter was an independent predictor of progression-free survival when 10.0 cm (hazard ratio [HR], 2.72; 95% confidence interval [CI] 1.19-6.22; P = .018), and 10.5 cm (HR, 2.77; 95% CI 1.21-6.33; P = .016) were chosen as the cut-offs.

Conclusions: In our study, only size-related recurrence or metastatic potential was found, and a 10.5-cm cut-off best stratified this difference. However, size-related cancer-specific and overall survival differences were not found among patients.