There are Public Health programmes which could prevent cancers developing or increase the probability that a cancer may be cured

Early detection is an important factor in reducing the death rate from cancer, whether it is achieved by personal actions or through participation in organised public health programmes. Awareness of different visual body signs or symptoms that could easily be observed by anyone and that are possibly related to cancer is important. It is unequivocally established that cancer survival is better for early, localised disease than for the later stage, advanced forms of the disease. Thus, the earlier in the process that a cancer can be diagnosed and treated then the better this is for the patient. Potential symptoms of cancer should not be ignored, but should serve as a clear warning for the individual to consult his or her doctor for advice. The signs and symptoms described in Table 10 are not specific for cancer. When any one is present, the individual should see a doctor. Much effort has gone into cancer screening and the development of methods for finding cancers at an earlier stage in their development and increasing the prospects of a cure. It is possible to make recommendations based on the available evidence.

:: Men and women from 50 years of age should participate in colorectal screening. This should be within programmes with built-in quality assurance procedures

The identification of a well-determined pre-malignant lesion, the adenomatous polyp, together with the good survival associated with early disease, make colorectal cancer an ideal candidate for screening. In the past quarter century, progress has been made in our ability to screen patients for colorectal cancer or its precursor state, using advances in imaging and diagnostic technology. Faecal occult blood guaiac test cards were first employed in the 1960s, the flexible sigmoidoscope was introduced in the mid-1970s to replace the rigid sigmoidoscope which had been first introduced in 1870, and colonoscopy has been available since 1970.

Four randomised trials have examined annual or biennial screening with Faecal Occult Blood Testing (FOBT) while there are only data available regarding sigmoidoscopy and colonoscopy from observational studies, and little yet from randomised trials. There is evidence from these randomised trials to support the use of FOBT with a reduction in colorectal cancer mortality of about 16% (95% Confidence Interval = 9% to 22%) from a meta-analysis [27% (95% CI =10% to 43%) reduction among those screened]. The proposed screening interval is 2 years, though it has been judged that yearly examinations are cost-effective.

Flexible sigmoidoscopy is an alternative or complementary method of screening. The higher sensitivity of colonoscopy over FOBT suggests that colonoscopy is more effective. A large randomised trial is underway which should have results in 2005 or 2006.

Despite the evidence showing that screening is worthwhile most citizens of developed countries have not been screened for colorectal cancer by any means. While this situation persists the chance is being missed to prevent about one quarter of the 138.000 colorectal cancer deaths which occur each year in the European Union.