The mutational landscape of adenoid cystic carcinoma (ACC) is currently being revealed, but further studies are needed to identify biomarkers as therapeutic targets or prognostic factors of ACC. In this study, we investigated the expression of epithelial cell adhesion molecule (EpCAM) in ACCs. We retrospectively collected 83 cases of surgically resected ACCs. Using tissue microarray, we conducted immunohistochemical staining using the anti-EpCAM antibody. EpCAM expression was analysed by

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... ty score and the total immunostaining score. The positivity was 97.6% (81/83 cases), regardless of the intensity score. A higher histological grade (p = 0.006) and specific tumour location (non-salivary gland origin, p = 0.02) showed a correlation with higher EpCAM intensity. Higher EpCAM expression by total immunostaining score was associated with histological grade (p = 0.004), distant metastasis (p = 0.004) and poorer prognosis (overall survival p = 0.015 and progressionfree survival p = 0.033). We suggest EpCAM as a candidate prognostic marker and a putative therapeutic target in ACC. Also, ACCs arising from salivary gland and non-salivary gland sites, respectively, might display different pathophysiologies in which EpCAM could play a role.