Immunohistochemistry (IHC) and fluorescent in situ hybridization (FISH) are reliable ways to identify overexpression of c-Met protein or amplification of the c-Met gene, but each technique requires a high-quality tissue sample, which may not be available. The aim of this study is to investigate whether plasma soluble c-Met level can be used to predict tissue c-Met status in patients with advanced non-small cell lung cancer (NSCLC).
In 198 patients with advanced NSCLC, we determined c-Met expression by IHC analysis on tumors. The expression was scored according to MetMAb scoring criteria. Plasma concentration of soluble c-Met protein was measured with a human soluble c-Met quantitative enzyme-linked immunosorbent assay (ELISA) kit, and the predictive values were determined based on the receiver-operating characteristic (ROC) curves analysis.
Of the total 198 patients, 103 (52%) patients were tissue c-Met negative, 95(48%) were tissue c-Met positive. The average plasma c-Met concentration was 682.8 Â± 155.2 ng/mL in the tissue c-Met-negative group, significantly lower than 886.5 Â± 307.4 ng/mL in tissue c-Met- positive group (P < 0.001). ROC curve analysis showed 66.9% specificity and 64.2% sensitivity for predicting tissue c-Met positivity at 755ng/mL of plasma c-Met. AUC for plasma c-Met was 0.724 (95% confidence interval; 0.654–0.794, P < 0.001).
We suggest 755 ng/mL in the plasma as a cutoff for predicting tissue c-Met status with moderate specificity and sensitivity. This information may be useful when the tumour tissue is not available.
Clinical trial identification
All authors have declared no conflicts of interest.