Clinicopathologic characteristics and outcomes of patients with anaplastic lymphoma kinase-positive advanced pulmonary adenocarcinoma: Suggestion for an effective screening strategy for these tumors

Introduction: The purpose of this study was to analyze the clinicopathologic characteristics and outcomes of patients with anaplastic lymphoma kinase (ALK)-positive advanced pulmonary adenocarcinoma and to devise an effective screening strategy to identify such patients. Methods: We screened advanced pulmonary adenocarcinoma patients to identify ALK-positive cases. The presence of ALK rearrangements was confirmed by fluorescence in situ hybridization. Results: Of the 221 screened patients, 45 demonstrated ALK rearrangements, and these individuals were younger than the ALK-negative patients (p < 0.001). The proportion of never smokers and light smokers was found not to differ according to the ALK status (p = 0.537). Epidermal growth factor receptor (EGFR) mutations and ALK rearrangements were found to be mutually exclusive. Thyroid-transcription factor-1 (TTF-1) expression was observed in all ALK-positive tumors for which immunohistochemistry data were available. The objective response rate and progression-free survival to first-line platinum-based chemotherapy showed no significant differences between ALK-positive and ALK-negative patients. On the other hand, no patient with ALK-positive tumors achieved objective tumor responses to EGFR tyrosine kinase inhibitors (TKIs). ALK rearrangements were not found among individuals who had EGFR mutations, an objective response to a previous EGFR TKI treatment or TTF-1-negative tumors. Conclusion: The clinical outcomes of platinum-based chemotherapy were found not to differ according to the ALK status. Both smokers and never/light smokers should be candidates for ALK screening. We suggest that the exclusion of patients with activating EGFR mutations, an objective response to previous EGFR TKIs, or TTF-1-negative tumors from ALK screening could be an effective enrichment strategy for ALK-positive cases.