Abstract
BACKGROUND: Plasma epidermal growth factor receptor (EGFR) mutation tests are less invasive than tissue EGFR mutation tests. We determined which of two kits is more efficient: cobas EGFR Mutation test v2 (cobasv2; Roche Molecular Systems, Pleasanton, CA, USA) or PANAMutyper-R-EGFR (Mutyper; Panagene, Daejeon, Korea). We also evaluated whether pleural effusion supernatant (PE-SUP) samples are assayable, similar to plasma samples, using these two kits. METHODS: We analyzed 156 plasma and PE-SUP samples (31 paired samples) from 116 individuals. We compared the kits in terms of accuracy, assessed genotype concordance (weighted κ with 95% confidence intervals), and calculated Spearman's rho between semi-quantitatively measured EGFR-mutant levels (SQIs) measured by each kit. We also compared sensitivity using 47 EGFR-mutant harboring samples divided into more-dilute and less-dilute samples (dilution ratio: ≥ or <1:1,000). RESULTS: cobasv2 tended to have higher accuracy than Mutyper (73% vs 69%, P=0.53), and PE-SUP samples had significantly higher accuracy than plasma samples (97% vs 55-71%) for both kits. Genotype concordance was 98% (κ=0.92, 0.88-0.96). SQIs showed strong positive correlations (P<0.0001). In less-dilute samples, accuracy and sensitivity did not differ significantly between kits. In more-dilute samples, cobasv2 tended to have higher sensitivity than Mutyper (43% vs 20%, P=0.07). CONCLUSIONS: The kits have similar performance in terms of EGFR mutation detection and semi-quantification in plasma and PE-SUP samples. cobasv2 tends to outperform Mutyper in detecting less-abundant EGFR-mutants. PE-SUP samples are assayable using either kit.