All High-Grade Ta Tumors Should be Classified as High Risk: Bacillus Calmette-Guerin Response in High-Grade Ta Tumors

Purpose: There is variation amongst guidelines with respect to risk stratification of Ta tumors, specifically high-grade (HG) Ta tumors. We sought to investigate the response of all Ta tumors to bacillus Calmette-Guerin (BCG) and compare response rates based on European Association of Urology (EAU) classification as intermediate-(IR) or high-risk (HR). Materials and Methods: An institutional review of all patients who received adequate BCG from 2000-2018 was conducted. EAU 2021 prognostic risk groups were used to stratify patients including by the newly proposed adverse risk factors. Results: When patient with Ta tumors were stratified into IR and HR, 37 (16%) had IR low-grade (LG) Ta, 92 (40%) had IR HG Ta and 101 (44%) had HR HG Ta tumors. BCG unresponsiveness developed in 13% of HR HG Ta tumors and 14% of IR HG Ta tumors compared to 0.0% of IR LG Ta tumors (p=0.003). While no patients with IR LG Ta tumors progressed, progression rates were similar in HR HG Ta and IR HG Ta tumors (>= T2: 5.9% and 6.5%; >= T1: 13% and 13%, respectively). Rates of recurrence, BCG unresponsiveness and progression were similar, irrespective of number of EAU risk factors present (p=0.9, p=0.8 and p=0.9, respectively). Conclusions: All HG Ta tumors, regardless of EAU risk stratification, have inferior response to BCG and increased rates of progression compared to IR LG Ta tumors. EAU clinical risk factors did not improve prediction of oncologic outcomes among HG Ta patients who received adequate BCG. These data support consideration of all HG tumors as high risk.