L-[3-18F]-α-methyltyrosine (18F-FMT) is an amino-acid tracer for positron emission tomography (PET). The investigators evaluated the value of 18F-FMT PET for the assessment of therapy response in patients with lung cancer as compared with that of 2-[18F]-fluoro-2-deoxy-D-glucose (18F-FDG) PET.