The standard treatment for an early stage I lung cancer is surgery. However, surgery can be associated with complications and long-term impairment of the quality of life of patients. Stereotactic radiotherapy (SRT) is a outpatient technique which allows for local control rates that are comparable to those achieved using surgery. In this study, patients with stage IA non-small cell lung cancer will be randomized to either surgery or SRT in order to study the local and regional tumor control, quality of life and treatment costs at 2- and 5-years.