First of all, in the situation that the diagnostic criteria of SMPLC are still not perfect, EGFR mutation can be a good supplement to histological, imaging and morphological evidence of tumor, so as to better distinguish multiple primary lesions from metastatic lesions and provide patients with a more accurate staging; Secondly, EGFR mutation can provide evidence of targeted therapy for patients; Finally, compared with patients with squamous cell carcinoma, patients with lung adenocarcinoma are more likely to be detected with EGFR mutations. The gene discussed is EGFR; the disease is squamous cell carcinoma.