GRP and lung cancer: Eight protein tumor markers (CA125, CA15.3, CEA, CYFRA 21-1, HE4, NSE, ProGRP, and SCCA) were measured using electrochemiluminescent assays, and ctDNA mutations in EGFR, KRAS, and BRAF were determined using droplet digital PCR in the blood of 1096 patients suspected of having lung cancer.