Cancer Research UK : Bowel Cancer screening and prevention

Bowel Cancer screening and prevention

Colorectal cancer is a good candidate for population-based screening for a number of reasons. Firstly, it is a major public health problem. Secondly, most cases develop slowly over a number of years as benign adenomas transform into malignant adenocarcinomas.

This provides the opportunity for early detection of asymptomatic conditions, either to remove polyps before malignant transformation or to treat neoplasms at an early stage when survival rates are high (Table 8.1).

Table 8.1: Approximate frequency and 5 year relative survival (%) by Dukes' stage

Download this table (14.5KB)

Three randomised controlled trials have shown that faecal occult blood testing (FOBT) every two years has the potential to reduce colorectal mortality in those screened by 15%.1-4

Based on the numbers of people attending screening in these trials, it is estimated that people actually attending screening have a 25% reduction in their risk of colorectal cancer.14

Evidence for colorectal screening was reviewed by the National Screening Committee (NSC) which recommended that two pilot studies be set up to evaluate mass population screening.5, 6

In 2000, the UK Colorectal Cancer Screening Pilot was launched in England and Scotland to evaluate the feasibility, practicality and acceptability of introducing a biennial FOBT screening programme within the NHS for people aged between 50–69. These pilots reported favourably with very similar results to the randomised trial in Nottingham.7

Uptake of the FOBT was 57%, 2% of tests were positive and the rate for detecting cancer was 1.62 per 1000 people screened. In the pilot trials, 48% of the screen-detected cancers were Dukes' stage A and 1% Dukes’ stage D.7

Following government approval, a NHS Bowel Cancer Screening Programme will be phased in over three years in England beginning in 2006.8 (The Scottish Bowel Screening Programme will begin in 2007, inviting people aged 50-74 years.9)

Men and women aged between 60–69 are to be invited to participate every two years by using FOBT kits in their own homes and returning them to laboratories for analysis. People over 70 will be able to request a FOBT kit.

Approximately 2% of tests will be positive and further investigation, usually by colonoscopy, will be offered. Most people with a positive test result will not have cancer and as colonoscopy is not without complications, other investigative techniques are being looked at.

One such method is CT colonography (virtual colonoscopy) which is a non-invasive method of visualising the bowel.10 A randomised multicentre prospective trial (SIGGAR1) is comparing CT colonography to visual colonoscopy and barium enema.11

The use of flexible sigmoidoscopy is also being investigated as a screening tool.12

A recent multicentre randomised trial tested the hypothesis that a single examination with flexible sigmoidoscopy at around the age of 60 could prevent 5,000 cancers in people aged 60-80.13 Final results are expected in 2008 but initial findings are that this screening regimen gives a high yield of neoplasia, and is safe, acceptable and feasible.

Improved methods of early detection and treatment, combined with targeted prevention strategies, will help to reduce the burden of colorectal cancer. Epidemiological research has contributed new information about physical activity, weight control, diet, and other lifestyle choices that can help individuals reduce their risk of the disease.

The NHS Bowel Cancer Screening Programme, when fully implemented, will significantly lower the mortality rates from this cancer. Research into screening techniques is likely to lead to their greater accuracy.

Many new drugs are in clinical development and molecular profiling will help to identify prognostic and predictive factors that will lead to more tailored treatments for this disease.

Further information on bowel cancer screening is available from the NHS Cancer Screening Programme

Cancer screening saves lives. But we know it could save even more.

Sign our pledge to show your support for our Screening Matters campaign calling on the UK governments to commit to getting more people into cancer screening and making sure the best possible programmes are available.

References

Hardcastle, J.D., et al., Randomised controlled trial of faecal-occult-blood screening for colorectal cancer. Lancet, 1996. 348(9040):
Kronborg, O., et al., Randomised study of screening for colorectal cancer with faecal-occult-blood test. Lancet, 1996. 348(9040): p. 1467-71
Mandel, J.S., et al., Reducing mortality from colorectal cancer by screening for fecal occult blood. Minnesota Colon Cancer Control Study. N Engl J Med, 1993. 328(19): p. 1365-71.
Atkin, W., Implementing screening for colorectal cancer. Bmj, 1999. 319(7219): p. 1212-3.
National Screening Committee, A Summary of the Colorectal Cancer Screening Workshops and Background Papers. 1998
Garvican, L., Planning for a possible national colorectal cancer screening programme. J Med Screen, 1998. 5(4): p. 187-94.
Results of the first round of a demonstration pilot of screening for colorectal cancer in the United Kingdom. Bmj, 2004. 329(7458): p. 133.
NHS Screening Programme
NHS Scotland, National Service Division.
(NICE), N.I.C.E., IPG129 Computed tomographic colonoscopy (virtual colonoscopy). 2005.
The NHS Health Technology Assessment Programme. 2006
UK Flexible Sigmoidoscopy Screening Trial Investigators, Single flexible sigmoidoscopy screening to prevent colorectal cancer: baseline findings of a UK multicentre randomised trial. Lancet, 2002. 359(9314): p. 1291-300.
Atkin, W.S., et al., Prevention of colorectal cancer by once-only sigmoidoscopy. Lancet, 1993. 341(8847): p. 736-40.
Hewitson P, Glasziou P, Irwig L, Towler B, Watson E. Screening for colorectal cancer using the faecal occult blood test, HemoccultCochrane Database Syst Rev 2007(1):CD001216.

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