RET and non-small cell lung carcinoma: Previous studies have suggested that ALK+ NSCLC may be associated with a higher frequency of brain metastases at initial diagnosis and cumulatively [34], and that RET+ NSCLC may be associated with a significant cumulative incidence of brain metastases during patients’ disease course (at a level intermediate between that observed in ALK+ NSCLC and ROS1+ NSCLC) [35].