EGFR and squamous cell lung carcinoma: In clinical characteristics analysis, result showed that central lung squamous cell carcinoma was more likely to metastasis with lymph node than peripheral lung squamous cell carcinoma (46.2%, 67/145 vs 28.9%, 26/90; P=0.019), while there were no significant differences in gender, age, tumor size, distant metastasis, tumor node metastasis (TNM) stage, and EGFR mutation.