The results elucidated that AUC of serum CYFRA21-1, SCC, and CEA conjugating with EBUS-TBNA to distinguish SCLC, lung adenocarcinoma, and LSCC was elevated versus alone detection of each index, manifesting that combined test was valuable to identify pathological types of LC. The gene discussed is CEACAM5; the disease is small cell lung carcinoma.