Lung cancer has the highest death rate among cancer types and anorexia is reported by a high percentage of patients, but the prevalence values may vary according to form of diagnosis. Anorexia is associated with reduced food intake, weight loss and a negative effect in quality of life and worse outcome. There is no gold standard for anorexia diagnosis. The anorexia cachexia scale (AC/S) from FAACT instrument has been proposed as a tool for diagnoses anorexia but a validated cut-off value for NSCLC patients is required. This study validates a cut-off value of AC/S for anorexia diagnosis in NSCLC patients.