title: Identifying patients with undetected gastro-oesophageal cancer in primary care: External validation of QCancer® (Gastro-Oesophageal).
abstract: OBJECTIVE
  To evaluate the performance of QCancer® (Gastro-Oesophageal) for predicting the risk of undiagnosed gastro-oesophageal cancer in an independent UK cohort of patients from general practice records.
  
  
  METHODS
  Open cohort study to validate QCancer® (Gastro-Oesophageal) prediction model. Three hundred sixty-five practices from the United Kingdom contributing to The Health Improvement Network database. 2.1 million patients registered with a general practice surgery between 01 January 2000 and 30 June 2008, aged 30-84years (3.7 million person years) with 1766 gastro-oesophageal cancer cases. The outcome, gastro-oesophageal cancer was defined as incident diagnosis of gastro-oesophageal cancer during the 2years after study entry.
  
  
  RESULTS
  The results from this independent and external validation of QCancer® (Gastro-Oesophageal) demonstrated good performance data on a large cohort of general practice patients. QCancer® (Gastro-Oesophageal) had very good discrimination with c-statistics of 0.93 and 0.94 for women and men respectively. QCancer® (Gastro-Oesophageal) was well calibrated across all tenths of risk and over all age ranges with predicted risks closely matching observed risks. QCancer® (Gastro-Oesophageal) explained 74.4% and 75.6% of the variation in men and women respectively.
  
  
  CONCLUSIONS
  QCancer® (Gastro-Oesophageal) is a useful tool to identify undiagnosed gastro-oesophageal cancer in primary care in the United Kingdom.
authors.affiliation: Centre for Statistics in Medicine, Wolfson College Annexe, University of Oxford, Linton Road, Oxford, UK. gary.collins@csm.ox.ac.uk
authors.forename: Gary S
authors.initials: GS
authors.lastname: Collins
authors.forename: Douglas G
authors.initials: DG
authors.lastname: Altman
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D057210:Delayed Diagnosis / Q000706:statistics & numerical data; D003951:Diagnostic Errors / Q000706:statistics & numerical data*; D055088:Early Detection of Cancer / Q000379:methods* / Q000592:standards; D004938:Esophageal Neoplasms / Q000175:diagnosis* / Q000453:epidemiology; D058006:General Practice / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D011237:Predictive Value of Tests; D011320:Primary Health Care / Q000706:statistics & numerical data*; D011379:Prognosis; D012306:Risk; D013274:Stomach Neoplasms / Q000175:diagnosis* / Q000453:epidemiology; D006113:United Kingdom / Q000453:epidemiology