Recruitment, response rates and characteristics of 5511 people enrolled in a prospective clinical cohort study: head and neck 5000

*School of Oral and Dental Sciences, National Institute for Health Research (NIHR) Biomedical Research Unit in Nutrition, Diet and Lifestyle, UniversityHospitals Bristol NHSFoundation Trust, School ofOral andDental Sciences, University of Bristol, Surgical Research Team, University Hospitals Bristol NHS Foundation Trust, School of Social and Community Medicine, University of Bristol, Bristol, UK National Cancer Research Institute Consumer Liaison Group (NCRI CLG), Independent Cancer Patients Voice (ICPV), London, UK **MRC Integrative Epidemiology Unit and Avon Longitudinal Study of Parents and Children, School of Social and CommunityMedicine, School of Clinical Sciences, University of Bristol, Bristol, Cochrane Oral Health Group, School of Dentistry, University of Manchester, Manchester, Royal Marsden Hospital and the Institute for Cancer Research, London, Leeds Institute for Cancer and Pathology, University of Leeds, Leeds, ***Evidence-Based Practice Research Centre (EPRC), Faculty of Health and Social Care, Edge Hill University, Ormskirk, Lancashire, UK