BACKGROUND: Patients with cancer are at increased risk for venous thromboembolism (VTE), and 8% to 15% of patients with advanced non-small-cell lung cancer (NSCLC) experience a VTE event during the course of their disease. The incidence of VTE in molecularly defined NSCLC subgroups is still unclear. In this study, we investigated the incidence and the clinical correlates of VTE in patients with ROS1-rearranged NSCLC enrolled in the METROS trial (NCT02499614).PATIENTS AND METHODS: The METROS trial is a prospective phase II study designed to assess efficacy, safety, and tolerability of crizotinib in patients with pre-treated metastatic NSCLC ROS1 rearrangement (cohort A) or with MET amplification or MET exon 14 mutation (cohort B). Patients with ROS1-rearranged NSCLC enrolled within cohort A and the expansion cohort of the trial were included in the primary analysis.RESULTS: Among 48 patients with ROS1-rearranged NSCLC enrolled in the METROS study, 20 (41.6%) of 48 had at least 1 VTE event. Among them, 7 (35%) of 20 patients had ≥ 2 VTE events. VTE events consisted of pulmonary embolism (46.4%), deep vein thrombosis (39.2%), renal vein thrombosis (7.1%), internal jugular thrombosis (3.5%), and peripheral inserted central catheter-related thrombosis (3.5%). VTE events occurred at disease progression in 35.7% of cases, at diagnosis in 32.1% of cases, and during chemotherapy or crizotinib in 17.8% and 14.2%, respectively.CONCLUSION: The incidence of VTE is 3- to 5-fold higher in patients harboring ROS1-rearrangment than previously observed for the general population with NSCLC. Larger studies are warranted to confirm our findings and determine whether the molecular profile of NSCLC should be incorporated into a risk-stratification tool and decision-making algorithm for VTE diagnosis and prophylaxis.