PDCD1 and neoplasm: Univariate analysis of the clinicopathological features of high and low PD-1 immune infiltrates and PD-L1 tumor cell expression revealed that tumors with high levels of PD-1 immune infiltrates were significantly more likely to lack lymphovascular invasion (P = 0.034; Additional file 1: Table S1), which is a key feature reflecting tumor aggressiveness [74, 75].