Best Response According to RECIST During First-line EGFR-TKI Treatment Predicts Survival in EGFR Mutation-positive Non-Small-cell Lung Cancer Patients

Those with a response to first-line gefitinib or afatinib had more favorable PFS and OS compared with those with stable disease. A sufficient observation period was required for the response to occur and predict outcomes. Greater maximal tumor shrinkage in the responders was not predictive of survival.