In our study, we comprehensively used both Kaplan-Meier plotter and PrognoScan to first conclude that decreased mRNA expression of TCF21 is an unfavorable prognostic factor in lung adenocarcinoma patients without gender difference and that TCF21 expression showed no prognostic value in patients with lung squamous cell carcinoma. The gene discussed is TCF21; the disease is squamous cell lung carcinoma.