PDCD1 and neoplasm: Choo et al. analyzed tissues from 350 patients with stage I–IV GC and found a strong correlation between PD-1+CD8+ tumor-infiltrating lymphocytes (TILs) and the expression of Ki-67 and Granzyme B. Their findings highlight the association between the presence of PD-1+CD8+ TIL and improved prognosis [23].