Immunohistochemical assessment of basal and luminal markers in non-muscle invasive urothelial carcinoma of bladder

The Cancer Genome Atlas project introduced genomic taxonomy of basal and luminal molecular subtypes in muscle invasive bladder cancer. Fewer studies have addressed the molecular classification in non-muscle invasive bladder cancer (NMIBC). Our aim is to assess the applicability of the proposed phenotypic classification for NMIBC. Three TMAs were constructed from 193 TURBT specimens of 60 bladder cancer patients treated at one of the authors' institutions (1998-2008). Follow-up data on recurrence, grade, or stage progression was obtained. Immunohistochemistry was performed using an automated Ventana System for markers indicative of luminal (GATA3, CK20, ER, Uroplakin II, and HER2/neu) and basal (CK5/6 and CD44) phenotype. Marker expression was evaluated by 3 urologic pathologists. Using unadjusted logistic regression, we found significant association between tumor recurrence at next biopsy and CD44 expression (OR = 2.51, P = 0.03), tumor recurrence at any subsequent biopsy and ER expression (OR = 0.24, P = 0.04), and tumor grade progression at any subsequent biopsy and HER2/neu expression (OR = 0.24, P = 0.04). After adjusting for pathologic stage, we found a significant association between CK5/6 expression and tumor stage progression at either next or any subsequent biopsy (OR = 0.94, P = 0.006; and OR = 0.97, P = 0.02, respectively). Our findings suggest that individual immunohistochemical markers may be of value as prognostic factors in NMIBC.