Original StudyAnalysis of Epidermal Growth Factor Receptor Mutations in Serum Among Japanese Patients Treated With First-Line Erlotinib for Advanced Non-Small-Cell Lung Cancer

BackgroundObtaining tumor samples for epidermal growth factor receptor (EGFR) mutation analysis during treatment can be difficult; therefore, serum samples may be a convenient alternative. We analyzed serum EGFR mutations in the Japanese phase 2 JO22903 study in chemotherapy-naive non-small-cell lung cancer patients with tumor EGFR mutations.Materials and MethodsSerum samples were analyzed by Scorpion-ARMS to detect EGFR mutations before and after erlotinib administration. Agreement between serum and tumor EGFR mutations and time course changes of EGFR mutations were evaluated.ResultsA total of 95 of 103 patients consented to examination of serum samples; baseline serum EGFR mutations (exon 19 deletions or L858R) were detected in 25 patients (26.3%). The agreement rate between tumor and serum samples was 96.2%. Among 65 serum samples taken at 190 days after treatment initiation, EGFR mutations were detected in 5 patients (7.7%). Of the serum samples taken at progression (n = 71), EGFR mutations were detected in 16 patients (22.5%). Patients with baseline serum EGFR mutations had a median progression-free survival of 9.7 months; those without baseline serum mutations had a median progression-free survival of 15.2 months.ConclusionThe sensitivity of these analyses was not enough to draw firm conclusions; however, the results suggest that serum EGFR mutations correlate with disease activity.