Stage pT1 Renal Cell Carcinoma: Review of the Prognostic Significance of Size

Abstract

Introduction: The last TNM classification (before 1997) defined T1 kidney tumour as a tumour <2.5 cm, limited to the kidney: this cut-off point was changed in 1997 and T1 neoplasm was defined as <7 cm. This new cut-off now includes past T1 and T2 diseases, without any differences in terms of prognoses. We performed a retrospective analysis of our cases and specifically investigated if there were any differences in terms of prognosis in a group of patients, currently identifiable as pT1, if they were divided into two subgroups based on tumour pathological sizes. Materials and Methods: Our analysis involved 128 patients (mean age 57.6 years) who underwent radical nephrectomy or nephron-sparing surgery in the period between 1990 and 2000. All these patients were pT1 according to the new TNM classification and were divided into two groups according to different cut-off point sizes (from 2.5 to 5 cm). We analysed the surgical approach, overall survival and cancer-specific mortality in the two subgroups, renamed as pT1a and pT1b, and performed a statistical analysis of the results using the Kaplan-Meier method to prove if this substaging identified changes in survival outcome. Results: We obtained more interesting results for a 5-cm cut-off: the two groups showed a similar follow-up and overall survival rate but different cancer-specific mortality rate (6 vs. 12.1%). The statistical analysis showed that the two survival curves (pT1a vs. pT1b disease) had a similar trend up to about 60 months; after this period the two curves diversify with a drop in survival rate among patients with larger tumours (pT1b patients). Conclusions: It would seem reasonable to reassess the TNM classification of stage pT1 in order to better define prognosis in this group of patients.