Mutations in exons 18-21 of EGFR TK domain were detected in 19 (23%) of the 81 NSCLCs in which there were 12 adenocarcinomas, three bronchioloaveolar carcinomas, two squamous cell carcinomas, one adenosquamous carcinoma, and one other type of NSCLC. This evidence concerns the gene EGFR and adenocarcinoma.