Clinical features of colorectal cancer before diagnosis: a population-based case-control study
British Journal of Cancer
Cancer Research UK and Nature Publishing Group
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Most colorectal cancers are diagnosed after the onset of symptoms. However, the risk of colorectal cancer posed by particular symptoms is largely unknown, especially in unselected populations like primary care. This was a population-based case-control study in all 21 general practices in Exeter, Devon, UK, aiming to identify and quantify the prediagnostic features of colorectal cancer. In total, 349 patients with colorectal cancer, aged 40 years or more, and 1744 controls, matched by age, sex and general practice, were studied. The full medical record for 2 years before diagnosis was coded using the International Classification of Primary Care-2. We calculated odds ratios for variables independently associated with cancer, using multivariable conditional logistic regressions, and then calculated the positive predictive values of these variables, both individually and in combination. In total, 10 features were associated with colorectal cancer before diagnosis. The positive predictive values (95% confidence interval) of these were rectal bleeding 2.4% (1.9, 3.2); weight loss 1.2% (0.91, 1.6); abdominal pain 1.1% (0.86, 1.3); diarrhoea 0.94% (0.73, 1.1); constipation 0.42% (0.34, 0.52); abnormal rectal examination 4.0% (2.4, 7.4); abdominal tenderness 1.1% (0.77, 1.5); haemoglobin <10.0 g dl(-1) 2.3% (1.6, 3.1); positive faecal occult bloods 7.1% (5.1, 10); blood glucose >10 mmol l(-1) 0.78% (0.51, 1.1): all P < 0.001. Earlier diagnosis of colorectal cancer may be possible using the predictive values for single or multiple symptoms, physical signs or test results.
Project funding from the Department of Health. The funding source had no role in study design, data collection, analysis or writing of the report. All authors had full access to all data, and take final responsibility for publication. WH was funded through his research practice (Barnfield Hill, Exeter) and RCGP/BUPA and NHS Fellowships. The views expressed in the publication are those of the authors and not necessarily those of the Department of Health. We wish to thank all 21 general practices in Exeter, the Dendrite personnel, and the Patients and Practitioners Service Authority, without which this project would not have been successful.
This is the final version of the article. Available from the publisher via the DOI in this record.
Vol. 93, pp. 399 - 405
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