 However, gFOBT has significant limitations. It is clear that this form of screening is associated with a substantial interval cancer rate in the region of 50 , indicating a severe deficiency in sensitivity for cancer. Furthermore, as it is now well established that the majority of colorectal cancers arise from pre-existing adenomas, it is important for any colorectal screening programme to detect adenomas in order to reduce the incidence of the disease as well as the associated mortality. Although gFOBT does detect some adenomas, the randomised studies have not demonstrated a reduction in colorectal cancer incidence with the exception of the Minnesota Study that used rehydrated gFOBT resulting in a high positivity rate and a large number of colonoscopies. It should be borne in mind however, that the newer faecal immunochemical tests FIT, which, unlike gFOBT, are specific for human haemoglobin, perform better in terms of both cancer and adenoma detection. 