SPDL1 and squamous cell carcinoma: 1. NSCLC patients showed increased levels of sPD-L1 compared to controls (p < 0.001);2. Lung adenocarcinoma patients had higher sPD-L1 levels than patients with squamous cell carcinoma (p < 0.01);3. No association was observed between the different genetic variants and plasma concentrations of sPD-L1.