Abstract: Objective   To investigate the relationship between epidermal growth factor receptor (EGFR) mutations and different clinical backgrounds in patients with nonsmall cell lung cancer (NSCLC). Methods  EGFR mutations in the tumor tissues of 257 NSCLC patients were analyzed by TaqManARMS (TaqManamplification refractory mutation system). The mutation of EGFR was explored in correlation with the clinicopathological features， TNM stage， gender， age and habits of patients. Results   99(38.5%) EGFR mutations， which were mainly located in exon 19 with the pattern of deletion mutation and exon 21 with the point mutation， were identified among 257 NSCLC patients. The mutation rate was higher in patients with adenocarcinoma and adenosquamous carcinoma than that in patients with  squamous cell carcinomas and other subtypes(all P<0.01). Mutation rate in female was higher than that in male(P<0.01). However， no evident association was found between EGFR mutation and age(P>0.05). EGFR gene mutations occurred more frequently in nonsmokers compared with smokers (P<0.01).  EGFR mutation was not associated with smoking years， but significantly correlated with daily smoking (P<0.01). There was no significant difference between EGFR gene mutation and clinical TNM stage of NSCLC(Ⅰ，Ⅱ， Ⅲ  and  Ⅳ).  EGFR mutation rates in patients with different pathological characteristics， to some extent， were different. Mutation was significantly different between low differentiation and middle or high differentiation (P<0.01). Conclusion  EGFR gene mutation in NSCLC was significantly correlated with gender， histological type， tumor differentiation， smoking and daily smoking amount but not with age， lymph node metastasis， TNM stages and smoking years.

Key words: carcinoma, nonsmall cell lung；receptor, epidermal growth factor； mutation