Prognostic Impact of pT3 Subclassification in a Multicentre Cohort of Patients with Urothelial Carcinoma of the Renal Pelvicalyceal System Undergoing Radical Nephroureterectomy: A Propensity Score-weighted Analysis After Central Pathology Review

Background The current pathological tumour-node-metastasis (pTNM) classification for upper tract urothelial carcinoma (UTUC) does not include any risk stratification of pT3 renal pelvicalyceal tumours. Objective To assess the prognostic impact of pT3 subclassification in a multicentre cohort of patients with UTUC of the renal pelvicalyceal system undergoing radical nephroureterectomy (RNU). Design, setting, and participants Data from all consecutive patients treated with RNU for pT3 renal pelvicalyceal UTUC at 14 French centres from 1995 to 2013 were reviewed retrospectively. Intervention A central pathology review (CPR) was used to stratify pT3 patients into those with infiltration of the renal parenchyma on a microscopic level (pT3a) versus those with infiltration of the renal parenchyma visible on gross inspection of the resection specimen and/or invasion of peripelvic fat (pT3b). Outcome measurements and statistical analysis Inverse probability weighting (IPW)-adjusted Cox regression analyses were used to compare recurrence-free survival (RFS) and cancer-specific survival (CSS) between pT3a and pT3b patients. Results and limitations Overall, 202 patients were included and further stratified into pT3a (n = 98; 48.5%) and pT3b (n = 104; 51.5%) subgroups. Median time to follow-up in the weighted population was 68 (interquartile range, 50–95) mo. In IPW-adjusted Cox regression analyses, pT3b versus pT3a substage was associated with a significant adverse effect on RFS (hazard ratio [HR] = 2.02; 95% confidence interval [CI] = [1.36–3.01]; p < 0.001) and CSS (HR = 1.84; 95% CI = [1.20–2.82]; p = 0.005). The study is limited by its retrospective design. Conclusions Using IPW-adjusted analyses after the CPR, we observed that RNU patients with pT3b renal pelvicalyceal UTUC had adverse prognosis as compared with those with pT3a disease. As such, this subclassification could help refine the current pTNM system for UTUC.