Fig. 2

a The extent of PD-L1 expression in the first and second quartiles (Q1, Q2) of serum sPD-L1 was lower than that in the third and fourth quartiles (Q3, Q4). b The association between PD-L1-postive tumor cells and serum levels of sPD-L1 (r = 0.299, P = 0.031). c The percentage of PD-L1-postive immune cells did not correlate with serum levels of sPD-L1. d, e Comparison of overall survival based on the percentage of PD-L1-positive tumor cells (< 1% versus ≥1%) and the percentage of PD-L1-positive immune cells (< 3% versus ≥3%)