SPDL1 and lung cancer: Other studies reported that the average sPD-L1 concentration in the sera of lung cancer patients (stage IV) was 248 pg/mL [22], which is in good agreement with the present findings (mean 240 pg/mL), whereas the average sPD-L1 concentration in the sera of healthy controls was 50–150 pg/mL [21], a lower value than our result (mean 256.6 pg/mL).