Reclassifying pT3 renal pelvic urothelial carcinoma with renal parenchyma invasion to pT2 improves correlation with overall survival

The American Joint Cancer Committee pT categorization in renal pelvic carcinoma defines pT3 as invasion of renal parenchyma, invasion of peripelvic fat, or both. However, survival heterogeneity within the pT3 category has been demonstrated. This investigation sought to compare survival between pT categories of renal pelvic urothelial carcinoma and identify modifications to improve correlation with survival. Pathology reports from nephroureterectomies performed at our institution from 2010 to 2019 were analyzed to identify primary renal pelvic urothelial carcinoma (n = 146). Tumors were stratified based on pT, pN, and invasion of renal parenchyma vs invasion of peripelvic fat with or without renal parenchyma invasion. Kaplan-Meier survival curves and Cox regression multivariate analysis were used to compare overall survival between groups. Similar survival curves were observed for pT2 and pT3 tumors. Multivariate analysis confirmed overlapping hazard ratios (HRs) for pT2 (HR = 2.64, 95% confidence interval [CI] = 0.69, 10.06) and pT3 (HR = 4.42, 95% CI = 2.08, 9.37). pT3 tumors with peripelvic fat invasion, regardless of renal parenchyma involvement, had a 3.3-fold worse overall survival than pT3 tumors with only renal parenchyma involvement. Additionally, pT3 tumors with only renal parenchyma invasion had similar survival compared to pT2, while pT3 tumors with peripelvic fat invasion had worse overall survival (p = 0.00091). Reclassifying renal parenchyma invasion as pT2 yielded greater survival curve separation and greater difference in HRs. For renal pelvic urothelial carcinoma, modifying the pT3 category to only include tumors with peripelvic fat invasion and expanding the pT2 category to include renal parenchyma invasion may improve pT correlation with overall survival.