Presence of variant histology (VarHst) in transurethral resection of bladder tumor (TURBT) biopsies and its prognostic significance on pathologic complete response (pCR) rates to neoadjuvant chemotherapy (neo-CTx).

Abstract

295 Background: Randomized phase III clinical trial data (S8710) supports an overall survival (OS) advantage with neo-CTx for muscle-invasive urothelial carcinoma (miUC) patients (pts) prior to cystectomy. Recent S8710 subset analyses have demonstrated an OS for pts with both pure UC and VarHst. pCR to neo-CTx has been suggested as a surrogate endpoint for OS. The relationship between VarHist in TURBT specimens and pCR rates is uncertain. Methods: A retrospective review of the Indiana University Simon Cancer Center urology and medical oncology clinical databases was performed spanning the years 1991 – 2012. Subjects with miUC, pathology reports available for both TURBT and cystectomy procedures, and confirmed receipt of neo-CTx with regimen details were included in this analysis. Pts with clinically positive lymph nodes (LN+) were included provided they underwent cystectomy with curative intent and distant metastases were not present. Associations between pCR and pt baseline age, gender, race, clinical stage (T2N0 vs. T3/T4/N+), chemotherapy regimen received (cisplatin combination therapy (CisCTx) vs. non-cisplatin based), and presence of VarHst on TURBT sample were tested by multinomial logistic regression analysis with statistical significance set at p<0.05. Results: 72 miUC pts satisfying the inclusion criteria were identified. Cohort demographics included: age (median) – 59 yrs, 76% male, 93% Caucasian, 63% T2N0, 32% LN+, 81% CisCTx neo-CTx regimen, 42% VarHst on TURBT, pCR for entire cohort 18%. The presence of VarHst on TURBT sample was not associated with decreased rates of pCR (6/30 vs. 7/42) p=0.610. A trend toward significance with age over 59 was also observed. Conclusions: The presence of VarHst in TURBT specimen is not associated with decreased rates of pCR at cystectomy in miUC pts treated with neo-CTx. Further characterization of the amount of VarHst and reproducibility of its recognition in TURBT samples is warranted to determine its ultimate clinical value.