Expression of S100A16 Is Associated with Biological Aggressiveness and Poor Prognosis in Patients with Bladder Cancer Who Underwent Radical Cystectomy

S100 calcium binding protein A16 (S100A16) is expressed in various cancers; however, there are few reports on S100A16 in bladder cancer (BC). We retrospectively investigated clinical data including clinicopathological features in 121 patients with BC who underwent radical cystectomy (RC). Immunohistochemical staining was performed to evaluate S100A16 expression in archived specimens. Cases with >5% expression and more than moderate staining intensity on cancer cells were considered positive. S100A16 expression was observed in 54 patients (44.6%). Univariate analysis showed that S100A16 expression was significantly associated with age, pT stage, recurrence, and cancer-specific death. Kaplan–Meier analyses showed that patients with S100A16 expression had shorter overall survival (OS), cancer-specific survival (CSS), and recurrence-free survival (RFS) than those without S100A16 expression. In multivariate analysis, pT stage was an independent prognostic factor for OS and lymph node metastasis for CSS and RFS. S100A16 expression may be a biomarker of a biologically aggressive phenotype and poor prognosis in patients with BC who underwent RC. The PI3k/Akt signaling pathway is probably associated with S100A16 and may be a therapeutic target.