A shorter mean distance between PD-L1+ tumor cells and PD-1+ T cells, as well as a higher percentage of PD-L1+ tumor cells within a 20 μm radius from PD-1+ CTL were found in HPV-positive primary tumors and lymph node metastases, as compared to HPV-negative lesions (Fig. 6F). Here, PDCD1 is linked to neoplasm.