ROS1 and squamous cell carcinoma: Over 30 ROS1 fusion partner genes have been identified in NSCLC, most commonly CD74, EZR, SCD4, and SLC34A2.1,4,15 Broad molecular testing, including for ROS1 fusions, is recommended by multiple guidelines including the National Comprehensive Cancer Network (NCCN) and European Society for Medical Oncology (ESMO) guidelines for patients with advanced lung adenocarcinoma, large cell, and NSCLC not otherwise specified, and should also be considered for those with advanced squamous cell carcinoma.16,17