The present study demonstrates a significant association between dMMR tumours and an increased PD-L1 expression on TC and/or TIC which is consistent with a study on gastric cancer by Kawazoe et al. (n = 487), wherein PD-L1 positivity (≥ 1%) on both TC and TIC was more frequently observed in dMMR tumours (35). This evidence concerns the gene CD274 and neoplasm.