Of note, there were no significant associations of any macrophage subsets with mismatch repair deficiency (dMMR), but CD163+ macrophage infiltration was positively associated with expression of programmed death ligand 1 (PD-L1) on tumor cells (p = 0.035), and MARCO+ density was positively associated with PD-L1 expression on both tumor cells (p = 0.009) and immune cells (p = 0.025). Here, MARCO is linked to mismatch repair cancer syndrome 1.