Stage pT1 renal cell carcinoma: review of the prognostic significance of size

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 cutoff 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.