Evaluating cell cycle progression score as a prognostic marker for non-muscle invasive bladder cancer (NMIBC).

Abstract

476 Background: Accurate grading and staging from transurethral resection of bladder tumors (TURBT) is vital for appropriate clinical management. Non-muscle-invasive bladder cancer (NMIBC) can recur progress with higher grade and or stage progression to MIBC, requiring radical intervention with poorer prognosis. Further, grade and stage may change in 20-50% of TURBTs following re-review by expert GU pathologists Objective measures of stage and grade might offer additional and/or improved risk stratification; therefore we evaluated a molecular RNA signature as a prognostic marker for NMIBC. Methods: Patients were diagnosed with NMIBC at the University of Minnesota (UM)or Spectrum Health System(SHS) from 2005-2012. A Cell Cycle Progression (CCP) score was determined from the average expression of 36 CCP genes for patients with available FFPE diagnostic TURBT. The combined cohort consisted of 293 patients (UM n = 152, SHS n = 141). Study outcome was time from NMIBC diagnosis to progression to MIBC. Median follow-up for patients who did not experience an event was 4.4 years for UM and 6.9 for SHS. Association with outcomes was evaluated by Cox proportional hazards survival analysis and likelihood ratio tests. All analyses were stratified by cohort. Results: CCP score was associated with progression to MIBC in univariable analysis [hazard ratio 1.42 (95% CI 1.19, 1.68), p = 4.3x10-5]. Tumor grade and stage were also highly prognostic. CCP score was strongly associated with stage (T1 vs Ta, p < 10-6) and grade (high vs low, p < 10-14) in both cohorts. As a result, CCP score did not provide independent prognostic information in multivariable analysis after adjusting for stage and grade (p = 0.32). There was a significant interaction between stage and CCP score (p = 0.0017), justifying an exploratory analysis of CCP score in Ta disease. In this subset, CCP score trended toward (p = 0.056) after adjusting for grade. Conclusions: In NMIBC, CCP score was highly correlated with tumor stage and grade and could serve as a quantitative measure of clinical parameters. The score may also provide prognostic information regarding risk of progression to MIBC, particularly in patients with Ta disease, but requires additional validation.