Pathologic response in patients receiving neoadjuvant chemotherapy for muscle-invasive bladder cancer: Is therapeutic effect owing to chemotherapy or TURBT?

PURPOSE: We estimated the proportion of patients who received neoadjuvant chemotherapy for muscle-invasive bladder cancer whose tumors were downstaged by transurethral resection.

MATERIALS AND METHODS: We identified patients with cT2 N0 urothelial carcinoma who underwent cystectomy at our institution from 2005 to 2014-overall, 139 underwent transurethral resection without chemotherapy, and 146 underwent transurethral resection with chemotherapy. Pathologic response was defined as<pT2 N0. We used a Poisson regression model to determine relative risk (RR) of pathologic response in nonneoadjuvant vs. neoadjuvant patients, adjusting for demographic and clinical covariates. This RR was used to estimate the response attributable to transurethral resection.

RESULTS: Neoadjuvant patients were younger than nonneoadjuvant patients (64.4 vs. 71.4 years, P<0.01), with higher median body mass index (28.4 vs. 26.6kg/m2 , P<0.01), lower prevalence of Charlson score≥3 (13.7% vs. 30.2%, P<0.01), and lower prevalence of prior non-muscle-invasive cancer (7.5% vs. 20.9%, P<0.01). More neoadjuvant patients achieved response compared with nonneoadjuvant patients (62.3% vs. 20.1%, RR = 3.10, P<0.01). Adjustment resulted in a RR of pathologic response in neoadjuvant vs. nonneoadjuvant patients of 2.60 (95% CI: 1.81-3.74, P<0.01). This adjusted RR indicates that among patients who receive neoadjuvant chemotherapy and undergo transurethral resection, 38% (95% CI: 27%-55%) of pathologic response can be attributed to transurethral resection.

CONCLUSIONS: We estimate that in a cohort of patients who receive chemotherapy and undergo transurethral resection before cystectomy, 38% of pathologic response can be attributed to transurethral resection. Understanding who responds to chemotherapy and who responds to transurethral resection is needed to measure the effectiveness of both interventions.