title: The Danish Head and Neck Cancer database.
abstract: The Danish Head and Neck Cancer database is a nationwide clinical quality database that contains prospective data collected since the early 1960s. The overall aim of this study was to describe the outcome of the national strategy for multidisciplinary treatment of head and neck cancer in Denmark and to create a basis for clinical trials.
  
  
  METHODS
  The study population consisted of all Danish patients referred for treatment of squamous cell carcinoma of the larynx, pharynx, oral cavity, or neck nodes from unknown primary or any histopathological type (except lymphoma) of cancer in the nasal sinuses, salivary glands, or thyroid gland (corresponding to the International Classification of Diseases, tenth revision, classifications C.01-C.11, C.30-C.32, C.73, and C.80).
  
  
  METHODS
  The main variables used in the study were symptoms and the duration of the symptoms; etiological factors; pretreatment and diagnostic evaluation, including tumor-node-metastasis classification, imaging, histopathology, and laboratory tests; primary treatment with semidetailed information of radiotherapy, surgery, and medical treatment; follow-up registration of tumor status and side effects; registration of relapse and treatment thereof; and registration of death and cause of death.
  
  
  RESULTS
  Data from >33,000 patients have been recorded during a period of >45 years. In this period, the outcome of treatment improved substantially, partly due to better treatment as a result of a series of continuous clinical trials and subsequent implementation in national guidelines. The database has furthermore been used to describe the effect of reduced waiting time, changed epidemiology, and influence of comorbidity and socioeconomic parameters.
  
  
  CONCLUSIONS
  Half a century of registration of head and neck cancer treatment and outcome has created the basis for understanding and has substantially contributed to improve the treatment of head and neck cancer at both national and international levels.
authors.affiliation: Department of Experimental Clinical Oncology, Aarhus University Hospital, Aarhus.
authors.forename: Jens
authors.initials: J
authors.lastname: Overgaard
authors.affiliation: Department of Experimental Clinical Oncology, Aarhus University Hospital, Aarhus.
authors.forename: Aleksandar
authors.initials: A
authors.lastname: Jovanovic
authors.affiliation: Department of ORL - Head and Neck Surgery; Department of Oncology, Odense University Hospital, Odense, Denmark.
authors.forename: Christian
authors.initials: C
authors.lastname: Godballe
authors.affiliation: Department of Oncology, Odense University Hospital, Odense, Denmark.
authors.forename: Jesper
authors.initials: J
authors.lastname: Grau Eriksen
keywords: head and neck cancer; national population cohort; radiotherapy; squamous cell carcinoma