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Screening and early diagnosis: Colorectal cancer

Dr Alison Round and Professor David Weller discuss the benefits of screening to identify early disease and the implications for GPs' workload

Dr Alison Round and Professor David Weller discuss the benefits of screening to identify early disease and the implications for GPs' workload

The incidence of bowel cancer in the UK is amongst the highest in the world. Nevertheless, survival rates in the UK have improved over the past 25 years, and about half of people with newly diagnosed bowel cancer will still be alive in five years' time. Efforts to tackle this disease have focused on early diagnosis and screening, although recently there have also been significant improvements in treatment.

There is good evidence supporting screening for bowel cancer, and it is likely to be an increasing feature in healthcare over the next several years.

Guaiac-based faecal occult blood testing (FOBT) is so far the only method of screening that has been shown to reduce disease-specific mortality; several trials have demonstrated reductions in colorectal cancer mortality of about 17 per cent in groups of people who are offered screening using FOBT.

A UK pilot of screening using FOBT was established in 2000; it demonstrated that a population-based programme could produce rates of uptake, test performance and pathology detected similar to those achieved in randomised controlled trials.

The pilot has now completed two rounds of screening in England and Scotland, and health ministers in both England and Scotland have committed to a national programme of screening for colorectal cancer.

Screening will follow a similar pattern to that established in the pilot – that is, there will be a number of screening centres (hubs) that will co-ordinate the programme, including invitations and follow-up, with endoscopy and other diagnostic and treatment services provided at more local and regional levels.

At present there is considerable activity in increasing capacity for colonoscopy, pathology and other services associated with colorectal cancer screening. There is also a great deal of work being undertaken to establish adequate information technology and quality assurance systems.

There are several important challenges for primary care with the initiation of this programme; the pilot demonstrated that, while general practices are not directly involved in recruitment to screening, they do have important roles in co-ordination and information provision, leading to modest but real impacts on workload.

Many people who take up an offer of screening are likely to be symptomatic. Bowel symptoms are highly prevalent in the UK population and there can be misconceptions about the use of screening tests such as FOBT; they are not an alternative to seeking medical care for symptoms and, indeed, might provide false reassurance in such circumstances.

Primary care has a role to play in educating patients about the strengths and limitations of this new programme; it will also have a key role in promoting uptake in hard-to-reach groups including those from socio-economically deprived backgrounds, males, those in younger age groups, and certain ethnic groups.

Other potential screening tests

There is interest in refinements to the standard guaiac-based FOBT, particularly the immunochemical test. As yet, it is not known whether these newer tests would perform better in a national programme. There is also growing interest in the use of flexible sigmoidoscopy, particularly as this is a screening modality that could be delivered in primary care. A randomised study of flexible sigmoidoscopy screening will report in the near future.

  • Dr Alison Round is a GP in Tiverton, Devon
  • Professor David Weller is a GP in Edinburgh and Professor of General Practice at Edinburgh University

This article is an extract from Cancer Diagnosis in Primary Care edited by William Hamilton and Tim J. Peters, ISBN 978-0-443-10367-4, published by Churchill Livingstone Elsevier, January 2007, Price £19.99. To order a copy please go to The Elsevier website or phone Elsevier customer services on 01865 474000

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