The diagnostic and follow-up role of radiological examination in advanced lung adenocarcinoma with anaplastic lymphoma kinase gene rearrangement

This study aimed to determine the imaging characteristics of patients with advanced lung adenocarcinoma who harbor anaplastic lymphoma kinase gene mutation (ALK+) and to explore the follow-up value of radiological examination of these patients. Forty patients with stage IV lung adenocarcinoma were enrolled, including 20 ALK+ patients (study group) and 20 patients with no ALK mutation (ALK-) (control group). In the study group, 20 patients were treated with crizotinib or chemotherapy randomly. All patients underwent serial enhanced neck-thoracic computed tomography (CT), abdominal-pelvic CT, and enhanced brain magnetic resonance imaging (MRI) during treatment. Compared to ALK- patients, ALK+ patients were significantly more likely to have advanced N stage disease, a larger short diameter of metastasizing lymph nodes (ND), and a higher ratio of ND/TD (long diameter of the primary tumor) (P = 0.002, 0.044 and 0.002, respectively). A cut-off value of ND/TD ≥ 0.84 was useful for identifying ALK+ patients, with a specificity of 100% and a sensitivity of 50%. Brain metastasis, as detected by brain MRI, was the most common cause of progression in patients treated with crizotinib. Thus, the ND/TD ratio may be of value in selecting candidates for ALK mutation screening, and enhanced MRI of the brain is necessary during crizotinib treatment of ALK+ patients.