EGFR and neoplasm: A retrospective study in China showed that the rate of uncommon mutations [i.e., mutations other than 19Del and L858R (15)] was high, with 12% of 1,837 Chinese patients with NSCLC EGFR mutations having non-classical mutations such as exon 20 insertion (30%), G719X mutation (21%), L858R complex mutation (17%; complex mutation defined as more than one EGFR mutation within a tumor sample) and T790M complex mutation (14%) (16).