The proportion of CD8+ PD-1High cells within CD8+ PD-1+ T cells was higher in peri-tumor cores than in tumor cores (P = 0.011), and the proportion of CD8+ PD-1Low cells within the CD8+ PD-1+ T cells was higher in tumor cores than in peri-tumor cores (P = 0.011) (Fig. 2b). Here, PDCD1 is linked to neoplasm.