Hence, the relatively low number of studied patients, but sufficient to show that: (a) the coexistence of two different sequences of KRAS point mutations at codon 12 is not a rare phenomenon in NSCLCs; (b) some NSCLCs reveal inhomogeneous distribution of KRAS mutation over the tumor tissue; and (c) there is a high accordance between KRAS mutation status in EBC–DNA and NSCLC tissue. This evidence concerns the gene KRAS and non-small cell lung carcinoma.