Bowel Symptoms in Relation to Colorectal Cancer
It is common in clinical practice to perform a colonoscopy in patients with symptoms, often with the aim of detecting or ruling out colorectal cancer. We present results from a systematic review and large primary clinical study that show that most bowel symptoms are not predictive of colorectal cancer. Considered individually, bowel symptoms that predicted colorectal cancer were rectal bleeding, change in bowel habit, rectal mucus and weight loss of more than 6 kg. Prediction was the strongest in those people who had symptoms weekly and of less than 12 months duration. When all bowel and general symptoms are considered together, only bleeding and rectal mucus remain predictive, and abdominal pain and anaemia become predictive.
A model based on age, gender and medical history was highly predictive. Age is a strong predictor of colorectal cancer, and consideration of symptoms adds little predictive value to that conferred by age alone. Therefore, with bowel symptoms being so common in the community, their role as a gatekeeper for access to colonoscopy needs review, especially in the context of other tests available—the predictive value of immunochemical faecal occult blood tests is also much higher than that of any symptom. Using a model based on age, medical history and symptoms the predicted probability of colorectal cancer can be assessed. In our study, 95% of cancers could have been detected by doing only 60% of the colonoscopies.
KeywordsBowel symptoms Colorectal cancer Predictive value Colonoscopy Age
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