We hypothesize that patients with elevated serum Mg levels who are treated with EGFR-TKI may have longer PFS and OS based on the following: EGFR mutations lead to increased Mg absorption; that is, elevated Mg levels indicate that EGFR mutations account for a higher proportion of tumor development, thereby increasing the sensitivity of EGFR-TKI treatment. The gene discussed is EGFR; the disease is neoplasm.