1. a Oncology Clinical Trials Office, Waterland Hospital, Purmerend, The Netherlands
2. c Department of Clinical Oncology, Leiden University Medical Centre, Leiden, The Netherlands;
3. d Department of Oral Medicine and Diagnostic Sciences, College of Dentistry and Department of Otolaryngology and Head and Neck Surgery and Cancer Center, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, USA;
4. e Section of Preventive Dentistry, Academic Centre for Dentistry, University of Amsterdam and VU University Amsterdam, Amsterdam, The Netherlands;
5. f Department of Oral Pathology, School of Dentistry, Faculty of Health Sciences, University of Adelaide, Adelaide, Australia;
6. b Department of Internal Medicine, Waterland Hospital, Purmerend, The Netherlands;
7. g Dermatology Service, Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York, USA