Despite scientific evidence, use of liquid biopsy (LB) in diagnosis and monitoring of lung cancer (LC) is limited since it requires major changes in diagnostic and care pathways. Analyzing tumor markers (TMs), circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA) in blood (LB) can inform about the nature of the tumor, the most appropriate therapy, therapy response and resistance. Lungmarker2 is a multicenter, prospective, implementation and diagnostic cohort study. This study aims to implement up-front ctDNA analysis ('plasma first approach') into routine diagnostic work-up of all advanced stage LC patients in the Southeast of the Netherlands (the participating hospitals in the OncoZON region). Thereby, additional information about the molecular make-up of the tumor becomes available, the number of tissue Next-Generation Sequencing (NGS) analyses will decrease and time to therapeutic decision making is shortened. Next, using ctDNA, TM and other information, multi-parametric decision support models are built and validated that may support diagnosis, predict the outcome of the next imaging procedure and progression-free survival during follow-up. The final goal is to develop a super-resolution microscopy test that can detect PD-L1 expression on CTCs.