CD8A and neoplasm: Several studies have identified CD8+ CTLs density in the tumor and in the invasive margin for assessing recurrence risk of CRC.2 CD8+ CTL infiltration can be as an independent predictor of favorable survival outcomes in patients with CRC.3 Moreover, hot tumors with the high degree of CD8+ CTL infiltration displaying high response rates to the immune checkpoint blockers.4 These findings imply that CD8+ CTLs are key defender of CRC.