Proposal of a new subcategory of the pT3 classification: Effects of tumor location and subclassification of renal pelvic pT3 to predict the prognosis of pelvic carcinoma more accurately than the current TNM classification.

Abstract

455 Background: Whether pT3 urothelial carcinoma of the renal pelvis (UCRP) and urothelial carcinoma of the ureter (UCU) show the same prognosis or not remains controversial.This study aims to reveal whether the prognosis of pT3 UCRP shows similar to those of pT3 UCU. Methods: We retrospectively evaluated 954 patients who underwent nephroureterectomy between 1983 and 2017 at our institutions.None of the patients received neoadjuvant therapy.All HE slides for each patient were reviewed by a single genitourinary pathologist (TT).pT3 UCRP was subdivided pT3a (urothelial carcinomas that extend only to the renal medulla) and pT3b (urothelial carcinomas that extend to the renal cortex and/or peripelvic adipose tissue) according to the criteria previously we proposed.Fine and Gray model was developed to predict the reccurence-free survival (RFS) and cancer-specific survival (CSS). Results: Overall, 954 patients were eligible for this study, 493 of whom were pT3 with only renal pelvis and 461 of whom were pT3 with only ureter. A total of 202 cases were pT3 UCRP and 146 were pT3 UCU. The pT3 subclassification of UCRP resulted in 79 pT3a and 120 pT3b cases.No significant difference was found in the 5-yr RFS and 5-yr CSS between pT3a UCRP and pT2 UCRP and pT2 UCU. (RFS; pT3a UCRP vs pT2 UCRP: HR = 1.19 p = 0.74; pT3a UCRP vs pT2 UCU HR = 0.88, p = 0.72, CSS;pT3a UCRP vs. pT2 UCRP: HR = 0.69; p = 0.56; pT3a UCRP vs. pT2 UCU: HR = 0.66, p = 0.31) The RFS rate was significantly higher in the pT3a UCRP than that of pT3b, (pT3a vs pT3b: HR = 2.59, p = 0.0038) and so was the CSS rate. (pT3a vs. pT3b: HR = 3.1 p = 0.001) In fine and gray model analysis for RFS, pT stage, lymph node metastasis, WHO/ISUP grade, lymphovascular invasion were independently associated with tumor recurrence, whereas pT stage, lymph node metastasis, operation method, histologic type, lymphovascular invasion, gross type, adjuvant chemotherapy were independently associated with cancer mortality. Conclusions: Subclassifying pT3 UCRP into pT3a and pT3b was useful in determining the prognosis of different patients.The pT3b UCRP showed similar outcome compared to those of UCU.