Use of faecal occult blood tests in symptomatic patients

Despite serious reservations expressed during consultation, the National Institute for Health and Care Excellence (NICE) has recently issued referral guidance for suspected colorectal cancer in which faecal occult blood testing (FOBT) is recommended for certain low risk symptomatic patients.1 2 We believe that this will lead to false reassurance and delayed investigations. We should like to point out that:

• 1. The guidance is particularly worrying for people under 60 with iron deficiency anaemia. Current NICE guidance on anaemia states that men and non-menstruating women of any age with unexplained iron deficiency anaemia should be referred urgently3

• 2. The guidelines do not specify which FOBT is recommended—the only one currently available in the UK is the guaiac test, which detects no more than 50% of colorectal cancers4

• 3. Guaiac FOBT based UK screening programmes require up to nine stool samples, and reliable interpretation is possible only in laboratories with dedicated staff and strict quality assurance. This test should be used only in this context and for population screening only

• 4. Anyone seeking advice about symptoms wishes reassurance that there is no serious disease. The guaiac test is not sufficiently sensitive for this purpose and because negative tests provide reassurance diagnosis is likely to be delayed

• 5. This comes at an unfortunate time—evidence is rapidly accumulating that quantitative faecal immunochemical testing (FIT), used at an appropriate cut-off concentration, can be useful for triaging symptomatic patients, including those who warrant urgent referral.5 Currently, however, FIT is available only for research and in very few centres.

Until there is a firm evidence base for the use of FIT at an appropriate cut-off level and FIT analysers become widely available, GPs should not use FOBTs to help investigate symptomatic patients.