Clinical Significance of Substaging and HER2 Expression in Papillary Nonmuscle Invasive Urothelial Cancers of the Urinary Bladder

The study aimed to verify the prognostic utility, therapeutic application and clinical benefits of tumor substaging and HER2 status in papillary non-muscle invasive bladder cancer (NMIBC). Select NMIBC transurethral resection specimens from 141 patients were used to construct tissue microarrays for assessing the substaging, HER2 protein expression by immunohistochemistry (HER2-IHC) and gene amplification by dual-color silver in situ hybridization (HER2-SISH). Substages were identified by the differing depth of tumor invasion (pTa / pT1a / pT1b / pT1c). HER2 protein expression was semiquantitatively analyzed and grouped into negative (score 0, 1+) and positive (score 2+, 3+). Other clinicopathological variables were also investigated. For NMIBC, HER2-IHC and HER2-SISH showed positive results in 6/141 (4.3%) and 4/141 (2.8%) respectively, which correlated well with tumor substaging. In multivariate analysis, substaging, HER2-IHC, and HER2-SISH were found to be independent predictors of progression-free survival (P < 0.001, P < 0.001, P = 0.031). HER2-IHC was the sole independent predictor of recurrent free survival in NMIBC (P = 0.017). It is suggested that tumor substaging and HER2 status are independent predictive markers for tumor progression or recurrence, and thus could be included in diagnostic and therapeutic management for NMIBC.