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)

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.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<0.05.72 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.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.