In 5 of the 6 studies reporting EGFR mutation status according to the histological subtype, there was a higher frequency of EGFR mutation in adenocarcinomas compared with other subtypes: (13 vs 0% [9], 40.6 vs 31.3% [13], 25 vs 0% [15], 32.46 vs 10.25% [16] and 36.25 vs 15,38% [17]). This evidence concerns the gene EGFR and adenocarcinoma.