MATERIALS AND METHODS: Two EGFR mutation tests, a tissue-based assay (cobas® v1) and a tissue- and blood-based assay (cobas® v2) were used to analyze matched biopsy and blood samples (897 paired samples) from three Asian studies of first-line erlotinib with similar intent-to-treat populations. ENSURE was a phase III comparison of erlotinib and gemcitabine/platinum, FASTACT-2 was a phase III study of gemcitabine/platinum plus erlotinib or placebo, and ASPIRATION was a single-arm phase II study of erlotinib. Agreement statistics were evaluated, based on sensitivity and specificity between the two assays in subgroups of patients with increasing tumor burden.
RESULTS: Patients with discordant EGFR (tissue+/plasma-) mutation status achieved longer progression-free and overall survival than those with concordant (tissue+/plasma+) mutation status. Tumor burden was significantly greater in patients with concordant versus discordant mutations. Pooled analyses of data from the three studies showed a sensitivity of 72.1% (95% confidence interval [CI] 67.8-76.1) and a specificity of 97.9% (95% CI 96.0-99.0) for blood-based testing; sensitivity was greatest in patients with larger baseline tumors.
CONCLUSIONS: Blood-based EGFR mutation testing demonstrated high specificity and good sensitivity, and offers a convenient and easily accessible diagnostic method to complement tissue-based tests. Patients with a discordant mutation status in plasma and tissue, had improved survival outcomes compared with those with a concordant mutation status, which may be due to their lower tumor burden. These data help to inform the clinical utility of this blood-based assay for the detection of EGFR mutations.
CASE REPORT: Both procedures were conducted with advanced airway under total intravenous anaesthesia. 2.6 mm GS was used in combination with a 2.2 mm rEBUS probe, using a therapeutic bronchoscope. Case 1 describes a SPN in the apical segment of the right upper lobe that was inconclusive by forceps biopsy due to GS displacement and inadequate biopsy depth. A steerable GS combined with the novel cryoprobe subsequently overcame this issue. Case 2 describes a SPN in the apical segment of the left upper lobe in which the standard cryoprobe failed to advance through the GS due to steep angulation. It also highlights with shorter activation time, the novel cryoprobe enable biopsied tissue to be retrieved through the GS while the bronchoscope-GS remains wedgend in the airway segment. There were no bleeding or pneumothorax complications in both cases, and histopathological examination confirmed adenocarcinoma of the lung.
CONCLUSION: The 1.1 mm flexible cryoprobe in combination with GS and therapeutic bronchoscope offers an option to acquire adequate tissue in difficult-to-reach regions in the lung such as the apical segment of upper lobes. Further prospective series to evaluate its performance and safety in SPN biopsy is highly anticipated.