To investigate the relationships between the expression of programmed death 1 (PD-1) and the epidermal growth factor receptor (EGFR) gene mutations in non-small cell lung cancer (NSCLC). The study also attempted to investigate the clinicopathological features and prognosis in NSCLC patients.The expression of PD-1 protein in 88 cases of NSCLC tumor tissues and adjacent tissues was detected by immunohistochemistry. The mutations of EGFR in NSCLC were detected by Polymerase Chain Reaction-Amplification Refractory Mutation System(PCR-ARMS) method. The expression of PD-1 and patients' clinical characteristics and prognosis were analyzed.PD-1 was positive in 63.6%(56/88) NSCLC tumor tissues, which was significantly higher than that in adjacent normal tissues (21.6%, 19/88) (<0.05). EGFR gene mutations were found in 43 cases (48.9%), in which 30 cases (69.8%)were PD-1 positive expression. 45 cases had the wild types of EGFR gene, in which 26 cases (57.8%) were PD-1 positive. There were 24 cases of 19Del EGFR mutations, including 20 cases (83.3%) of PD-1 positive expression. 19 patients had 21L858 EGFR mutations, including 10 cases (52.6%) of PD-1 positive expression. The expression of PD-1 in NSCLC was related to patients' smoking status, lymph node metastasis and EGFR gene mutations (<0.05). The median progression-free survival time of patients with PD-1 positive and negative expression was 7.03 and 18.66 months, respectively (=0.007). In patients with wild-type EGFR gene, the median progression-free survival time of PD-1 positive and negative expression was 25.21 and 38.24 months, respectively. The difference was statistically significant (=0.024). The median progression-free survival time in 43 cases of EGFR mutant patients with PD-1 positive and negative expression was 21.23 and 31.44 months. The difference was not statistically significant (=0.128).PD-1 expresses in both EGFR mutant and wild-type NSCLC, and its expression levelis different with various EGFR mutations. The expression of PD-1 in NSCLC is related to the prognosis of patients, and the prognosis of patients with positive PD-1 expression was poor. Objective: Methods: Results: Conclusions: P P P P P
