Impact of histologic variants on the oncological outcomes of patients with upper urinary tract cancers treated with radical surgery: a multi-institutional retrospective study

Background No definitive evidence exists regarding the clinical significance of histologic variants (HV) in upper urinary tract cancer. We investigated the impact of HV on prognosis in patients with upper urinary tract cancer following radical surgery. Patients and methods We retrospectively analyzed 451 patients with upper urinary tract cancer who underwent radical nephroureterectomy at six affiliated hospitals from 1990 to 2015. Patients with distant metastatic disease prior to surgery and those who received neoadjuvant chemotherapy were excluded, leaving 441 eligible patients. Patients were classified into two groups: pure urothelial carcinoma (UC) and HV. The clinicopathological variables of each group were examined using Kaplan-Meier plots and proportional Cox hazard ratios (HR) to compare the oncological outcomes between the two groups. Results HV included 37 patients (8%). Compared with the pure UC patients, HV patients had significantly worse recurrence-free survival (RFS) and cancer-specific survival (CSS; RFS p=0.0002, CSS p=0.0001). Multivariate analysis for RFS revealed HV were independent predictors (HR 1.92; p=0.026), but the association did not remain significant for CSS. There was no significant difference in CSS between the adjuvant chemotherapy (AC) group and the non-AC group for all HV patients, except in patients with >= pT3 tumor or positive lymph node status where the AC group had significantly favorable CSS. Conclusions HV in upper urinary tract cancer are independent predictors for RFS, but not for CSS. AC improved CSS for HV patients with >= pT3 tumor or positive lymph node status.