Bowel cancer screening and prevention

Colorectal cancer is a good candidate for population-based screening since it is an important public health problem and there is an effective and safe screening test. Most cases of colorectal cancer develop slowly over a number of years from adenomas, or benign polyps, which can transform into malignant adenocarcinomas. This provides the opportunity for screening to detect and treat benign polyps before malignant transformation occurs. (Note some polyps turn out to be cancerous when they are found). Screening can also detect colorectal cancers at an early stage when survival rates are highest (Table 8.1).

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section updated 22/03/11

Four randomised controlled trials showed that population screening with the faecal occult blood test (FOBT) every two years has the potential to reduce colorectal mortality by between15% and 18% in people aged 45-74.1-4

Those who attend screening have a 25% reduction in their risk of dying from colorectal cancer.4,5

In 2000, the UK Colorectal Cancer Screening Pilots were launched in England and Scotland. These studies evaluated the feasibility, practicality and acceptability of introducing a population screening programme with biennial FOBT within the NHS for people aged between 50-69. These pilot studies reported favourably with very similar results to the randomised trial in Nottingham.2,6-10

Uptake of the FOBT in the pilots was 57%. The rate of colorectal cancer detection was 1.62 per 1,000 people screened. Additionally, 48% of the screen-detected cancers were Dukes' stage A and only 1% Dukes’ stage D.6,7

The NHS Bowel Cancer Screening Programme was phased in over three years in England starting in 2006 for people aged 60-69.8,11 (The Scottish Bowel Screening Programme began in 2007, inviting people aged 50-74 years.9,12) Similar screening programmes started in Wales in 2008, and in Northern Ireland in 2010 for men and women aged 60-69.13,14  The English and Welsh programmes are gradually extending to men and women aged 70-74.

In all programmes men and women of the relevant ages are to be invited to participate every two years by using FOBT kits in their own homes and returning them to laboratories for analysis. In England people aged over the target age group can opt-in to the scheme and request a FOBT kit.

Approximately 2% of tests are positive and further investigation, usually by colonoscopy, is offered. Most people with a positive test result will not have cancer .

section updated 22/03/11

The use of  flexible sigmoidoscopy (flexi-sig) has also been investigated as a screening tool through a recent multicentre randomised trial.15,16  This trial showed that a once-only flexi-sig between the ages of 55 and 64 could reduce colorectal cancer incidence by 33% and mortality from colorectal cancer by 43% in those attending screening.17   The test was also to be found to be safe, acceptable and feasible.15

The NHS in England is introducing flexi-sig screening for men and women when they reach the age of 55. People aged over 55 will be able to request flexi-sig screening up to their 60th birthday. At 60, people will be offered the FOBT as now, whether or not they have had screening with flexi-sig. Pilots for the flexi-sig programme will begin in 2011/12, and it is expected that coverage of 30% of the English population will be achieved by April 2014, 60% by April 2015 and full coverage will be achieved in 2016.18

section updated 09/01/12