PDCD1 and neoplasm: The median of tumour centre and invasive margin CD3+ and CD8+ densities had a strong positive correlation with immune cell PD-1 expression in the tumour centre (rs = 0.631; p < 0.001) and in the invasive margin (rs = 0.697; p < 0.001), and immune cell PD-L1 expression (rs = 0.405; p < 0.001).