EGFR and adenocarcinoma: Early studies found that the mutation frequency of EGFR was lower than other adenocarcinomas (undetectable to ~28% in IMA vs. 47%–78% in non-IMA patients) (14, 15), while the frequency of KRAS mutations was higherin IMA than other adenocarcinomas (14%–86% in IMA vs. 1.5%–17% in non-IMA patients) (16, 17).