As the immune cells were associated with the response of drug treatment [19], we observed that infiltrating levels of macrophage M2 and resting natural killer (NK) cells were increased in nonresponders of CRT, and T cells that had anticancer activities such as activated memory CD4 and T helper 2 (Th2) cells were significantly reduced in ESCC tissues of the nonresponders. Here, CD4 is linked to esophageal squamous cell carcinoma.