 Aims and perspectives The overall purpose of this study is to increase our knowledge concerning molecular mechanisms - especially the development of resistance - in EGFR M NSCLC. Increased molecular knowledge is crucial in the development towards a more personalized cancer care. It provides us with better methods in selecting which treatment is the optimal choice for each individual patient. The investigators expect our results to validate the use of EGFR M detection and quantification via blood samples in a clinically relevant setting complementing CT scans in treatment evaluation. The investigators expect to be able to identify disease progression earlier than it would be possible using CT scans alone and thereby discovering more cases of oligoprogressive disease eligible for local treatment thus - hopefully - increasing the progression free survival. 