CD274 and cancer: In this study, we investigated the mutational status of ARID1A in CRCs using next generation sequencing (NGS) to reveal other co‐occurring cancer‐related mutations, the number of other mutations, and evaluate the relationship between PD‐L1 and ARID1A expression by immunohistochemistry (IHC) to test whether ARID1A‐mutant CRCs are more likely to express PD‐L1.