Predicting significance of EGFR mutation existing in tissues and plasma concuurrently or alone to EGFR–tyrosine kinase inhibitors (EGFR-TKIs) for advanced non-small cell lung cancer.

e19091 Background: To investigate predicting significance of EGFR mutations existing in tissues couples with plasma or either sample alone to EGFR–tyrosine kinase inhibitors (EGFR-TKIs) treatment for advanced non–small-cell lung cancer (A-NSCLC). Methods: Two hundred-eighty-seven A-NSCLC patients met following criteria were included into this study: 1) had received EGFR-TKIs as first- or second-line therapy; 2) had sufficient tissue and plasma samples for EGFR mutation analysis. All patients were divided into four subgroups which were wild-type EGFR in both of specimens (B-/T-), mutated in both of specimens (B+/T+), mutated only in one specimen (B+/T- and B-/T+). EGFR mutation was screened by denaturing high performance liquid chromatograph (DHPLC) and confirmed by ARMS. Objective response rate (ORR) and progression-free survival (PFS) were compared among four subgroups. Results: Of all 287 patients, 101 patients carried EGFR mutation both in tissue and plasma, 103 patients carried mutation only in tissue (65 cases) or plasma (38 cases). Median PFS was 9.2 months (95% CI, 6.3 to 12.1) and 2.0 months (95% CI, 1.3 to 2.7) in B+/T+ and B-/T- group, respectively. For single mutated group, mPFS were 7.87 month for B-/T+ group (95% CI, 5.1 to 10.6) and 11.87 months for B+/T- group (95% CI, 3.3 to 20.5) (P=0.001). For ORR, 53.0% for B+/T+ group, 15.8% for B-/T- group, 40.0% for B-/T+ group and 28.9% for B+/T- group (P=0.000). EGFR-TKIs therapeutic line could not change trend which B+/T- or B+/T+ group had better PFS than B-/T+ group. Conclusions: Detection of EGFR mutation in tissue and plasma may have different significance in predicting response of EGFR-TKIs.