However, according to the theory of “EGFR addition”, which refers to the dependency of cancer cells on EGFR mutation to maintain their malignant phenotypes[15], lung cancer patients harboring mutations in the tyrosine kinase domain of their EGFR genes should survive much longer, in response to the EGFR-TKI therapy, than the actual result. The gene discussed is EGFR; the disease is lung cancer.