1. University Depamnent of Surgety, University Hospital of South Manchester and Christie Hospital, Manchester, UK
2. Department of General Surgery, Wythenshawe Hospital, Manchester, UK
3. Imperial Cancer Research Fund, Clinical Oncology Unit, London, UK
4. Salivary Gland Service, Department of Oral and Maxillofacial Surgery, United Medical and Dental Schools, Guy's Hospital, London, UK