In this retrospective cohort study, the clinical characteristics and bronchoscopic findings of patients with ALK fusion-positive lung cancers were compared to patients with EGFR-mutant lung cancers.
Among the 440 patients with adenocarcinoma of lung screened for this study, 46 (10.4%) harboured the EML4-ALK fusion, 90 (20.4%) harboured an activating EGFR mutation, and all had adenocarcinoma. In univariate analysis, ALK-positive patients were significantly younger than EGFR-positive patients (p聽=聽0.004) and were more commonly male (p聽=聽0.021). An initial status of stage IV metastatic cancer was more frequently noted in EML4-ALK-positive patients (p聽=聽0.012), with initial brain metastasis frequently observed (p聽=聽0.007). Compared with EGFR-positive patients, EML4-ALK-positive patients were significantly more likely to have positive bronchoscopic findings, which suggested a more centralized origin (p聽=聽0.001). EML4-ALK patients also had significantly more positive bronchoscopic findings and were more commonly male in multivariate analysis.
The EML4-ALK fusion defines a new molecular subset of NSCLC that has distinct clinical and bronchoscopic findings suggesting more proximal origin when compared to tumours harbouring EGFR mutations.