Type of bleeding key in colon Cancer
GPs should not rely on rectal bleeding alone when making referrals for suspected colorectal cancer, researchers warn.
Their study appears to challenge research published in the BMJ recommending referral for all patients over 45 with new-onset rectal bleeding.
The researchers instead advised GPs to investigate the specific type of rectal bleeding as part of an overall risk assessment. But they stressed GPs should also not rule out the possibility of colorectal cancer in patients whose bleeding appeared to be caused by haemorrhoids – after detecting the disease in 2 per cent of these cases.
'Rectal bleeding as an isolated symptom has insufficient diagnostic value to be useful in general practice,' the researchers reported in the British Journal of General Practice.
But among 604 referrals to a sigmoidoscopy service in Southampton, the type of bleeding was significantly related to cancer risk. Patients with colorectal cancer were 2.1-fold more likely than those without the disease to have dark blood, and 1.5 times more likely to have blood mixed with stools.
This likelihood ratio rose to 3.0-fold when the symptoms were combined. Haemorrhoids did not significantly reduce risk.
Professor David Weller, professor of general practice at the University of Edinburgh and one of the study researchers, said: 'There is not that much to be gained from looking at rectal bleeding in isolation. Type of rectal bleeding may be more useful as part of a broader symptom score.
'If GPs see a patient with bright red rectal bleeding and haemorrhoids, that usually allays their concern. But there is growing evidence it doesn't significantly reduce the chance of cancer. GPs should be vigilant.'
But Dr William Hamilton, author of the BMJ paper and senior clinical research fellow in primary health care at the University of Bristol, said: 'My view is increasingly that all patients over 45 with new onset rectal bleeding should be investigated whatever the accompanying symptoms or character.'
NICE guidance Refer over-40s with new-onset rectal bleeding and six-week bowel habit change
BMJ study Refer all over-45s with new-onset rectal bleeding
New BJGP study Consider referral for patients over 45 with rectal bleeding mixed with stool
Do not rule out cancer in patients with haemorrhoids
By Lilian Anekwe