Is There a Need to Further Subclassify pT2 Renal Cell Cancers as Implemented by the Revised 7th TNM Version?

BackgroundThe recently modified TNM classification of renal cell carcinoma (RCC) (7th edition) has implemented a subdivision of pT2 tumours into stage pT2a (>7 or ≤10 cm) versus pT2b disease (>10 cm).ObjectiveOur aim was to evaluate whether this subdivision of pT2 RCC is justified due to a clinical prognosis divergence between the two groups (pT2a vs pT2b)Design, setting, and participantsIn total, 5122 patients were subjected to either radical nephrectomy or nephron-sparing surgery at three centres in Germany (University Hospitals of Hannover, Homburg/Saar, and Marburg). Patients were reclassified into stage pT2a and pT2b according to the maximum tumour diameter as suggested by the 7th revised version of the TNM classification system.MeasurementsThe t test and Fisher exact test were applied to evaluate the comparability of the two groups (pT2a vs pT2b) regarding several additional patients’ and tumour-specific characteristics of known prognostic relevance for RCC. Univariable (Kaplan-Meier analysis) and multivariable statistical analyses (Cox proportional hazards regression model) were applied to identify a possible difference between the two groups (pT2a vs pT2b) regarding cancer-specific survival (CSS).Results and limitationsApplying the new TNM classification, 579 previously pT2-staged patients were divided into 445 (76.9%) with pT2a and 134 (23.1%) with pT2b tumours. Kaplan-Meier curves revealed no significant difference in CSS between pT2a and pT2b patients; 5-yr CSS was 79.0% and 74.1%, respectively (p = 0.38). When applying multivariable analysis, unlike tumour grade and N/M status, pT2 subclassification failed to independently predict survival in RCC patients.ConclusionsThe new subclassification of pT2 RCC into two different subgroups as suggested by the latest modification of the TNM system does not yield additional/prognostic information.