Background: The discovery of the chromosomal fusion product of anaplastic lymphoma kinase (ALK) with echinoderm microtubule-associated protein-like 4 (EML4) (EML4-ALK) has changed the treatment paradigm of lung cancer. In this study, we analysed the clinical characteristics, including bronchoscopic findings, of patients with EML4-ALK-positive adenocarcinoma and compared them with those of EGFR mutation-positive patients.
Materials and methods: 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.
Results: 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 = 0.004) and were more commonly male (p = 0.021). An initial status of stage IV metastatic cancer was more frequently noted in EML4-ALK-positive patients (p = 0.012), with initial brain metastasis frequently observed (p = 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 = 0.001). EML4-ALK patients also had significantly more positive bronchoscopic findings and were more commonly male in multivariate analysis.
Conclusions: 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.
Keywords: Bronchoscopy; EGFR; EML4-ALK; Lung adenocarcinoma.
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