Incidence of T3a up-staging and survival after partial nephrectomy: Size-stratified rates and implications for prognosis.

BACKGROUND

The use of partial nephrectomy (PN) to treat renal cell carcinoma has grown to include larger, more complex tumors. Such tumors are more likely to be up-staged to pT3a and generate controversy regarding the oncologic safety of PN. We aimed to estimate the proportion of patients up-staged to T3a disease after PN, stratified by clinical stage, and characterize their survival.

METHODS

From 1998 to 2013, pT1-pT3aN0M0 kidney cancer patients undergoing PN or radical nephrectomy (RN) were identified from the Surveillance Epidemiology and End Results registries. Cox proportional hazards models compared cancer-specific (CSS) and overall survival (OS) for PN patients with pT1a, pT1b, and pT2 disease to stratified, up-staged pT3a patients undergoing PN. Also, we compared PN patients with up-staged pT3a disease to RN patients with pT3a disease.

RESULTS

From the 28,854 patients undergoing PN, the estimated proportion up-staged to pT3a was 4.2%, 9.5%, and 19.5% for cT1a, cT1b, and cT2, respectively. OS was worse for tumors up-staged from cT1a to pT3a, but not for cT1b or cT2 tumors. Up-staged pT3a tumors across all stage strata demonstrated worse CSS, with worse survival for larger tumors. Analysis revealed no difference in OS or CSS for up-staged pT3a PN patients compared to pT3a RN patients.

CONCLUSIONS

A greater proportion of patients experience T3a up-staging after PN with increasing initial T stage. Up-staged pT3a patients have worse CSS across all clinical tumor stages after PN. However, our results do not demonstrate that patients up-staged after PN have compromised oncologic outcomes compared to all-comers with pT3a disease receiving RN.