 We expect our results to validate the use of EGFR M detection and quantification via blood samples in a clinically relevant setting. The investigators expect earlier identification of disease progression to allow more cases of local treatment thus - hopefully - increasing the progression free survival. Continued blood monitoring in subsequent lines of treatment and treatment intermissions will add to our knowledge of the nature of EGFR M NSCLC. The sampling of biological material allows us to further investigate the biology of resistance. 