Subjects Subjects with lung cancer detected by a computed tomography (CT)-scan and referred to a positron emission tomography (PET)/CT-scan are included. The diagnosis of lung cancer is confirmed by means of an pathological biopsy or by a medical doctor specialized in oncology with respect to radiological or clinical data. The control group consists of subjects who were referred to the department Nuclear Medicine for an examination of the heart. This control group represents the average population, consists of healthy subjects and patients with non-cancer diseases and did not undergo a PET/CT-scan. Exclusion criteria are as follows: (1) not fasted for at least 6 hours, (2) poorly controlled diabetes (fasting plasma glucose concentration ≥ 200 mg/dl) in cancer patients, (3) medication intake at the day of blood sampling and (4) treatment or history of cancer in the preceding 5 years.