ALK and lung cancer: In the absence of biopsy, the blood samples of patients with lung cancer are the only source of information for analyzing clinically relevant genetic changes, including epidermal growth factor receptor (EGFR), Kirsten rat sarcoma viral oncogene (KRAS), v-raf murine sarcoma viral oncogene homolog B1 (BRAF), c-ros oncogene 1 (ROS1), and anaplastic lymphoma kinase (ALK) (Allan-Blitz et al., 2018).