Anaplastic lymphoma kinase gene rearrangements in patients with advanced-stage non-small-cell lung cancer: CT characteristics and response to chemotherapy

Few articles have been published on the imaging findings of anaplastic lymphoma kinase (ALK)-positive non-small-cell lung cancer (NSCLC). To investigate the radiological findings of ALK-positive NSCLC in the advanced stage, CT scans were examined. In addition, the response to chemotherapy was evaluated. Of the 36 patients with ALK-rearranged NSCLC, a mass and a nodule were identified in 17 (47.2%) and 16 (44.4%), respectively, indicating that more than 40% had a small-sized tumor. Overall, 31 (86.1%) patients had lymphadenopathy, seven (19.4%) had extranodal lymph node invasion, and three (8.3%) had lymphangitis. A pleural effusion was seen in 15 patients (41.7%). All but one patient had no ground-glass opacity (GGO) lesions, indicating that most ALK-positive tumors showed a solid growth pattern without GGO on CT. Twenty were evaluable for response to chemotherapy; 10 (50.0%) had a partial response (PR), nine (45.0%) had stable disease (SD), and one (5.0%) had progressive disease (PD) with first-line chemotherapy. With second-line chemotherapy, five (26.3%) had PR, 11 (57.9%) had SD, and three (15.8%) had PD. The five patients with PR were all treated by using crizotinib. Time to progression was 8.2 months with first-line chemotherapy, and 6.0 months with second-line chemotherapy. Advanced-stage ALK-positive tumors have a relatively aggressive phenotype, which cannot be inferred from the size of the tumor alone. ALK-positive patients have a good response to first-line cytotoxic drugs and to crizotinib as second-line therapy, but a relatively poor response to cytotoxic drugs as second-line therapy.