The potential for bias exists from: (1) misclassification due to data entry and reporting errors in the EMR and use of database algorithms (e.g., line of therapy, adherence to oral EGFR-TKIs), (2) missing or incomplete data (e.g., ECOG performance status, comorbidities, tumor response to therapy), and (3) unmeasured or unknown confounding bias despite the use of multivariable regression to control for measured prognostic factors. Here, EGFR is linked to neoplasm.