ABSTRACT
<p><b>OBJECTIVE</b>To investigate epidermal growth factor receptor (EGFR) gene mutations in exons 19 and 21 of patients with non-small cell lung cancer (NSCLC) and to analyze the relationship of EGFR mutations with clinicopathological features and prognosis.</p><p><b>METHODS</b>The EGFR gene exons 19 and 21 of paraffin-embedded tumor tissue were amplified by PCR, followed by direct sequencing in 282 surgically-removed specimens of NSCLC. The relationship of EGFR gene mutations in NSCLC with clinicopathological features and prognosis were analyzed.</p><p><b>RESULTS</b>EGFR mutations were detected in 120 of 282 (42.6%) patients with NSCLC. There were 61 cases of the mutations in exon 19 and 66 cases of the mutations in exon 21, including 7 cases of the mutations both in exons 19 and 21. Mutations were more frequently observed in women (55.2%, 53/96) than in men (36.0%, 67/186), in 51 to 60-years-old (51.3%, 39/76) than ≤50-years-old (30.4%, 21/69) and >60-years-old (43.8%, 60/137), in non-smokers (54.3%, 69/127) than smokers (32.9%, 51/155), there was negative correlation of EGFR mutations with smoking status (P=0.000, rs=-0.216). EGFR mutations were more frequently observed in adenocarcinomas (47.8%, 64/134), bronchiolo-alveolar carcinomas (73.0%, 27/37), adenosquamous carcinomas (7/9) than squamous cell carcinomas (23.6%, 17/72) and other types (16.7%, 5/30). The EGFR mutation rate in the well differentiated, the middle differentiated, the poorly differentiated and the undifferentiated was 55.7% (68/122), 50.8% (30/59), 22.7% (17/75), 19.2% (5/26) respectively, the incidences of EGFR mutations decreased with the degrading of differentiation, there was positive correlation of EGFR mutations with differentiation of lung cancer (P=0.000, rs=0.296). The patients with EGFR mutations had better prognosis than those with wild-type EGFR (P=0.027). There was no association of EGFR mutations with clinical TNM stage.</p><p><b>CONCLUSIONS</b>EGFR mutations occur frequently in females, non-smokers and adenocarcinomas, bronchioloalveolar carcinomas, and adenosquamous carcinomas. The patients with EGFR mutations have better prognosis. The results may offer a practical approach to select the patients who may benefit from anti-EGFR target therapy.</p>