Abstract
OBJECTIVE: Anaplastic lymphoma kinase (ALK) rearrangement is an important oncogenic driver in some non-small cell lung cancers (NSCLC). Treatment with ALK tyrosine kinase inhibitors improves survival. The availability of diagnostic immunohistochemistry (IHC) has led to a paradigm shift in ALK testing. This study examined the prevalence of ALK rearrangement in Jordanian patients with NSCLC and compared the results of IHC and fluorescence in situ hybridization (FISH) for detecting ALK rearrangement. METHODS: This retrospective study on 449 patients with NSCLC treated at the King Hussein Cancer Center in Jordan tested biopsy samples for ALK rearrangement using FISH and/or IHC (D5F3) between 2018 and 2020. RESULTS: Eighteen patients (4%) had ALK-positive NSCLC. The calculated sensitivity and specificity of ALK immunostaining compared with FISH were 87.5% and 96%, respectively. ALK-positive patients were significantly younger than their ALK-negative counterparts, and women were three times more likely to carry ALK rearrangement than men. ALK rearrangement was significantly associated with smoking history, with most ALK-positive patients being non-smokers, former smokers, or light smokers. CONCLUSIONS: IHC is a reasonable alternative to FISH for ALK testing with advantages in terms of robustness, turnaround times, and cost-effectiveness.