title: The CAPER studies: five case-control studies aimed at identifying and quantifying the risk of cancer in symptomatic primary care patients.
abstract: BACKGROUND
  This paper reviews the background to five primary care case-control studies, collectively known as the CAPER studies (Cancer Prediction in Exeter). These studies, on colorectal, lung, prostate and brain tumours, sought to identify the particular features of cancer as reported to primary care. They also sought to quantify the risk of cancer for symptoms and primary care investigations, both individually and paired together.
  
  
  METHODS
  Two studies were on colorectal cancer: the former with 349 cases used hand searching and coding of entries, while the latter obtained 6442 cases from a national electronic database. The lung and prostate studies had 247 and 217 cases, respectively, and used manual methods. The brain study also used a national electronic database, which provided 3505 cases.
  
  
  RESULTS
  Generally, the symptoms matched previous series from secondary care, though the risks of cancer, expressed as positive predictive values, were lower. Rectal bleeding in colorectal cancer, and haemoptysis in lung cancer both had positive predictive values of 2.4%. The risk of a brain tumour with headache was one in a thousand.
  
  
  CONCLUSIONS
  The results identify areas where current guidance on urgent referral for investigation of suspected cancer could be improved.
authors: Department of Community Based Medicine, NIHR School for Primary Care Research, University of Bristol, 25-27 Belgrave Road, Bristol, UK. w.hamilton@bristol.ac.uk
authors: W
authors: W
authors: Hamilton
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000175:diagnosis / Q000209:etiology; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000209:etiology; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis / Q000209:etiology; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000175:diagnosis* / Q000209:etiology; D011320:Primary Health Care; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000209:etiology