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

Head and neck cancer is an important cause of ill health with rapidly changing aetiology and approaches to treatment. 1, 2 Survival appears to have improved but the reasons for this are unclear. 3 There is no large population-based comprehensive longitudinal biomedical resource of people with head and neck cancer. Several registries exist, such as the US National Cancer Institute surveillance epidemiology and end results programme, but these lack individual consent and biological samples. 4 Large retrospective aetiological case-control studies with consent, clinical and socio-demographic information and biological samples, such as the International Head and Neck Cancer Epidemiology Consortium, have limited follow-up data, focus on past rather than current exposures and recruited people at different stages of treatment. 5 Existing prospective studies have fewer than 1000 participants and are often based on follow-up of randomised trials (a potentially unrepresentative group). 6 The importance of adequately-powered, population-based, comprehensive, longitudinal biomedical resources in healthy populations is accepted. The value of similar biomedical resources for clinical conditions is increasingly appreciated. We report here on recruitment, response rates and characteristics of 5511 people enrolled in a prospective clinical cohort study: head and neck 5000.