The prognosis in colorectal cancer depends on the stage at which the disease is diagnosed. Patients with advanced disease usually die of cancer, but when large intestinal tumours are found at an early asymptomatic phase a cure can be anticipated. Furthermore, the premalignant lesions—adenomatous polyps—grow in the colon for years and perhaps decades before malignant conversion occurs, providing an opportunity for their removal, interrupting the natural history of these neoplasms. It has long been recognised that preventive strategies would be appropriate for this disease, and an extensive literature can be found on the subject

Two general approaches to detecting asymptomatic early staged colorectal cancers have been studied in dept. The first is the use of faecal occult blood tests as colorectal neoplasms add blood to the stool that can be detected prior to the development of symptoms. However, this approach is relatively weak due to deficiencies in both sensitivity and specificity. One can expect a reduction of colorectal cancer mortality of <20% if the test is performed every other year.1-3 False positive tests greatly outnumber true positives, all of which require a full investigation. The test is easy and non-invasive, but compliance is poor. This approach is often used but enthusiasm for this should be limited. The second approach is to perform endoscopic screening on asymptomatic individuals …