title: Predicting colorectal cancer risk in patients with rectal bleeding.
abstract: BACKGROUND
  Rectal bleeding is an important symptom of colorectal cancer but has low predictive value in primary care.
  
  
  OBJECTIVE
  To determine which characteristics of rectal bleeding, along with other factors, are predictive of colorectal cancer.
  
  
  METHODS
  Observation study of patients with rectal bleeding referred to an open-access diagnostic clinic.
  
  
  METHODS
  Primary care, southern England.
  
  
  METHODS
  Symptom data were collected, using a self-completed questionnaire. Logistic regression techniques were used to determine predictors of colorectal cancer.
  
  
  RESULTS
  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; > or = 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Community Health Sciences, General Practice Section, University of Edinburgh, 20 West Richmond Street, Edinburgh EH8 9DX.
authors.forename: Roma
authors.initials: R
authors.lastname: Robertson
authors.forename: Christine
authors.initials: C
authors.lastname: Campbell
authors.forename: David P
authors.initials: DP
authors.lastname: Weller
authors.forename: Rob
authors.initials: R
authors.lastname: Elton
authors.forename: David
authors.initials: D
authors.lastname: Mant
authors.forename: John
authors.initials: J
authors.lastname: Primrose
authors.forename: Karen
authors.initials: K
authors.lastname: Nugent
authors.forename: Una
authors.initials: U
authors.lastname: Macleod
authors.forename: Rita
authors.initials: R
authors.lastname: Sharma
mesh_terms: D000368:Aged; D015179:Colorectal Neoplasms / Q000150:complications* / Q000175:diagnosis; D042241:Early Diagnosis; D005194:Family Practice; D005260:Female; D006471:Gastrointestinal Hemorrhage / Q000209:etiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012002:Rectal Diseases / Q000209:etiology*; D012017:Referral and Consultation; D012307:Risk Factors; D012812:Sigmoidoscopy