Based on this case, D761Y is widely defined to be a secondary drug-resistant mutation of EGFR-TKI.[11] However, in the following year, Tokumo et al wrote a letter to the editor of clinical cancer research, to raise doubts about the case report of Balak et al, which was unable to evaluate the D761Y mutation in the pretreatment specimen because of no remaining DNA. This evidence concerns the gene EGFR and cancer.