LAUSR

Background Tumour microenvironments can differ according to intratumoural locations. We investigated the immune status at different locations in primary tumours and its clinical significance in oesophageal squamous cell carcinoma (ESCC). Methods The number of CD8 + tumour-infiltrating immune cells (TIICs) and PD-1 + TIICs, and PD-L1 expression on tumour cells (PD-L1 TC ) were immunohistochemically examined in the surface (Surf), centre (Cent) and invasive front (Inv) of tumours surgically resected from 192 patients with ESCC. Results The PD-L1 + rate was lower in Inv than in Cent (12.0% vs. 18.2%, P  = 0.012), although the numbers of CD8 + TIICs and PD-1 + TIICs were comparable among intratumoural locations. High numbers of CD8 + and PD-1 + TIICs and positive PD-L1 TC were related to better overall survival (OS) only in Surf and Cent (CD8: P  = 0.012 in Surf, 0.018 in Cent, and 0.165 in Inv; PD-1: P  = 0.028 in Surf, 0.021 in Cent, and 0.208 in Inv; and PD-L1: 0.044 in Surf, 0.026 in Cent, and 0.718 in Inv). Positive PD-L1 TC in Surf and/or Cent but not in Inv demonstrated a strong tendency toward better OS ( P  = 0.053). Conclusions Immune microenvironments according to the intratumoural location have different effects on the survival of patients with ESCC.