Volumetric Tumor Response and Progression in EGFR-mutant NSCLC Patients Treated with Erlotinib or Gefitinib

The 8-week tumor volume decrease was validated as a marker for longer survival in the independent cohort of EGFR-mutant NSCLC patients treated with first-line erlotinib or gefitinib. The volumetric tumor growth rate after the nadir in this cohort was similar to that of the previous cohort, indicating the reproducibility of the observation among different patient cohorts.