Published: 17/02/2005, Volume II5, No. 5943 Page 33

The issue

Colorectal cancer screening using faecal occult blood testing is to be rolled out nationally from April next year.

The supporting evidence is strong: a meta-analysis of the results from four randomised controlled trials published in the 1990s showed that it reduced mortality from colorectal cancer by 16 per cent.

However, the authors concluded that, although the results were positive, more information was needed on community response to screening.

The study

A pilot assessed the feasibility of national screening for colorectal cancer based on faecal occult blood testing.

This took place in the two health authorities in Coventry and Warwickshire and the Scottish Health Boards of Grampian, Tayside and Fife.

A total of 478,250 residents in the pilot areas aged 50-69 were invited to take part in the screening programme.

Over 56.8 per cent were able to provide a satisfactory stool sample for analysis. Of these, 1.8 per cent (5,050) had positive results and were invited for colonoscopy.

In all, 4,116 individuals underwent colonoscopy, with 3,700 having a complete colonoscopy.

This resulted in the detection of 552 cancers, of which over 70 per cent were at Dukes' stage A/B.

In practice

This pilot demonstrates that colorectal cancer screening is outside the confines of a randomised controlled trial.

However, there were significant losses at each stage, with 40 per cent of patients failing to return a satisfactory test and over 10 per cent failing to complete the colonoscopy assessment.

Uptake tended to increase with age and women were more likely to comply than men.

According to a recent review (Lancet 2005;365:153) the ideal screening method for colorectal cancer remains controversial and no test is unequivocally better than another.

New screening modalities such as virtual colonoscopy and molecular stool and blood testing may offer better alternatives to faecal occult blood testing over the next few years.

Overall, it is important to appreciate that screening is only about risk reduction and patients who have undergone any screening should be aware of the possibility of a false negative result.

The public should continue to be encouraged to report significant symptoms such as rectal bleeding, change in bowel habit or abdominal pain to their GP, irrespective of any screening result.

Summerton N. Diagnosing Cancer in Primary Care.

Radcliffe Medical Press: Abingdon 1999.

UK Colorectal Cancer Screening Pilot Group. BMJ 2004; 329: 133-5.

Weitz J, Koch M, Debus J et al. Lancet 2005; 365: 153-165.

Nick Summerton is a GP and PCT medical director.