1. Laboratory of Hygiene, Social & Preventive Medicine and Medical Statistics, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
2. Division of Medical Oncology, Department of Medicine, University of Washington, Seattle, WA 98195, USA
3. Department of Internal Medicine, Medical School, Aristotle University of Thessaloniki, Papageorgiou General Hospital Thessaloniki, 56403 Thessaloniki, Greece