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Logo of brjgenpracRCGP homepageJ R Coll Gen Pract at PubMed CentralBJGP at RCGPBJGP at RCGP
Br J Gen Pract. 2006 October 1; 56(531): 763–767.
PMCID: PMC1920716

Predicting colorectal cancer risk in patients with rectal bleeding

Roma Robertson, MSc, Research Fellow, Christine Campbell, PhD, Research Fellow, David P Weller, MRCGP, PhD, Professor in General Practice, and Rob Elton, PhD, Consultant Statistician
Community Health Sciences, General Practice Section, University of Edinburgh
David Mant, FRCGP, FRCP, Professor of General Practice
Department of General Practice, University of Oxford
John Primrose, FRCS, MD, Professor of Surgery
Department of Surgery, University of Southampton, Southampton General Hospital
Karen Nugent, MA, MS, FRCS, Senior Lecturer in Surgery
Department of Surgery, University of Southampton, Southampton General Hospital
Una Macleod, PhD, MRCGP, Senior Lecturer
General Practice and Primary Care, Community Based Sciences, University of Glasgow
Rita Sharma, MMBS, MSc, Clinical Lecturer



Rectal bleeding is an important symptom of colorectal cancer but has low predictive value in primary care.


To determine which characteristics of rectal bleeding, along with other factors, are predictive of colorectal cancer.

Design of study

Observation study of patients with rectal bleeding referred to an open-access diagnostic clinic.


Primary care, southern England.


Symptom data were collected, using a self-completed questionnaire. Logistic regression techniques were used to determine predictors of colorectal cancer.


There were 604 patients in the study and 22 (3.6%, 95% confidence interval [CI] = 2.0% to 5.2%) were diagnosed with colorectal cancer. Significant predictors of colorectal cancer were found to be age (<50 years: odds ratio [OR] = 1; 50–69 years: OR = 5.1, 95% CI = 1.4 to 18.6; ≥70 years: OR = 8.2, 95% CI = 2.1 to 31.8) and blood mixed with the stool (Likelihood ratio [LR] 1.5; adjusted OR = 3.8; 95% CI = 1.4 to 10.5). Presence of haemorrhoids associated with bright red bleeding not mixed with stool reduced the likelihood of cancer (OR = 0.4, 95% CI = 0.1 to 1.2) but did not eliminate it — a cancer was present in 2% of patients with these symptoms.


Patient-reported type of rectal bleeding as an isolated symptom has insufficient diagnostic value to be useful in general practice. By studying referred patients, we may even have overestimated its value. At best, it could be useful as a component of a composite symptom score to guide referral decisions.

Keywords: colorectal neoplasms, early diagnosis, general practice, sigmoidoscopy, signs, symptoms

Articles from The British Journal of General Practice are provided here courtesy of Royal College of General Practitioners