EGFR and lung carcinoma: Adenocarcinomas are now regarded as the most common lung carcinoma subtype, constituting approximately 40% of all non-small cell lung cancers (NSCLC) [24] and molecular analysis of EGFR exons 18, 19, 20, 21 is recommended in all adenocarcinoma or lung tumors with an adenocarcinoma component [10].