Effect of chemotherapy and/or TURBT on pathologic response in patients receiving neoadjuvant chemotherapy for muscle-invasive bladder cancer.

Abstract

395 Background: Neoadjuvant chemotherapy (NAC) for muscle−invasive bladder cancer (MIBC) has been associated with a survival benefit in patients who achieve pathologic response. However, a smaller but significant group of patients who receive transurethral resection of bladder tumor (TURBT) without NAC will also be down−staged. We estimated the prevalence of pathologic response to TURBT in patients who receive NAC. Methods: Of 737 serial patients who received radical cystectomy (RC) at Johns Hopkins Medical Center from 2005–2014, 328 with cT2 urothelial carcinoma were identified. 172 patients received NAC and TURBT, while 156 received only TURBT prior to RC. Demographic, clinical, and pathologic information was compared between groups using Wilcoxon−Mann−Whitney for continuous and chi−squared for categorical variables. Pathologic response was defined as < pT2 at RC. A Poisson regression model with robust error variance was used to determine relative risk (RR) of pathologic response in NAC vs. non−NAC patients, adjusting for age, body mass index (BMI), race, gender, Charlson score, smoking status, days from MIBC diagnosis to surgery, and history of prior non−MIBC (NMIBC). Results: Pathologic response was higher in NAC patients compared to non−NAC patients (62% vs. 21%, RR = 3.00). NAC patients were significantly younger than non−NAC patients (64.8 vs. 71.2 years, p < 0.01), with higher BMI (28.1 vs. 26.7 kg/m2, p < 0.01), lower frequency of Charlson score ≥ 3 (13.4% vs. 26.7%, p < 0.01), and lower frequency of prior NMIBC (9.4% vs. 22.4%, p < 0.01). Adjustment resulted in a RR of pathologic response in NAC vs. non−NAC patients of 2.50 (95% CI: 1.69−3.69, p < 0.01). Assuming no interaction between NAC and TURBT, this adjusted model suggests that in a cohort of patients who receive NAC, 40% (95% CI: 27–59%) of pathologic response can be attributed to TURBT. Conclusions: An adjusted model suggests that in a cohort of patients who receive NAC and TURBT prior to RC, 40% of pathologic response can be attributed to TURBT. An understanding of which patients are true responders to chemotherapy and which receive a therapeutic TURBT is needed to select optimal candidates for NAC.