Confirmation of lung adenocarcinoma as the primary cancer with detection of EML4-ALK rearrangement using next-generation sequencing: a case study.

We report a female patient, who presented as a carcinoma of unknown primary site with multiple tumors in breast, lung, stomach, and ovary, was confirmed to be lung adenocarcinoma as primary cancer through detecting EML4-ALK rearrangement by the next generation sequencing (NGS). The patient was treated with crizotinib and resulted in significant regression of the primary and metastatic tumors, but resistance to crizotinib was developed 5 months after the treatment. Targeted therapy was, therefore, switched to alectinib, one of the second-generation of anaplastic lymphoma kinase (ALK) inhibitors, with excellent therapeutic response till November 16th, 2021. This study suggested that NGS be recommended to detect ALK rearrangement in the patients with carcinoma of unknown primary site, and that resistance to targeted therapy with ALK inhibitors should be considered for personalized precision medicine.