P1-056 - Cytokeratin 19 Fragment (CYFRA21-1) Predicts the Efficacy of the Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor (EGFR-TKI) in Non-Small-Cell Lung Cancer (NSCLC) Harboring EGFR Mutation

Abstract

ABSTRACT Background EGFR mutation is independently associated with a favorable response in NSCLC patients receiving EGFR-TKIs, regardless of gender or smoking history. However, recent reports have indicated that squamous cell carcinoma patients harboring EGFR mutations show a worse response to EGFR-TKIs than adenocarcinoma patients. We hypothesized that serum CYFRA21-1 is a predictive marker in EGFR-mutated patients treated with EGFR-TKIs. Methods We retrospectively screened 160 NSCLC patients harboring EGFR mutations (exon 19 deletions, L858R in exon 21, or other minor mutations) who received either gefitinib or erlotinib between 1992 and 2011. Patients were screened for histology, sex, age, smoking status, efficacy of EGFR-TKI and tumor markers (CEA/CYFRA21-1) at initial diagnosis. Results Out of 160 eligible patients treated with EGFR-TKIs, 77 patients with a high CYFRA21-1 level (>2 ng/ml) showed statistically shorter progression-free survival (PFS) than 83 patients with a normal CYFRA21-1 level (median PFS 7.5 versus 14.0 months, P = 0.006). No significant difference in PFS was observed between the high CEA group (>5 ng/ml) and the normal CEA group (median PFS 8.6 versus 11.2 months, P = 0.2423). Multivariate analysis revealed that a high CYFRA21-1 level is independently associated with PFS (HR 1.35; P = 0.002) as well as squamous cell carcinoma (HR 1.40; P = 0.020) and performance status 2–4 (HR 2.63; P = 0.003). No statistically significant difference in overall survival (OS) was observed between the high CYFRA21-1 group and the normal group (median OS 24.8 versus 39.1 months, P = 0.104). Conclusions High CYFRA level patients have significantly shorter PFS, which may indicate that this subgroup has a larger squamous component and thus less response to EGFR-TKIs. The serum CYFRA21-1 level is a predictive marker of EGFR-TKIs efficacy and EGFR-mutated patients can be divided into two subgroups according to the CYFRA21-1 level at initial diagnosis.