Screening methods do not reveal all types of cancer. Both screening methods in this pilot project, (flexible sigmoidoscopy done once, or testing for hidden blood in the stool every other year), are expected to discover 60-70 per cent of tumours in the colon and rectum.
A positive screening test can also often be a false alarm. Eight out of ten who are told that they have hidden blood in their stools do NOT have cancer. However, there is a greater possibility that they have polyps (possible precancerous lesions). These can effectively be removed by colonoscopy, and thereby prevent the development of cancer.
Screening and health check ups may give a feeling, consciously or unconsciously, of being well taken care of and thereby reduce motivation to take responsibility for ones own health e.g. (continue smoking, too little exercise or an unhealthy diet).Screening involves, as a rule, only one disease – in this case colon cancer.
A healthy life style is important for much more regarding health in general, which screening can not replace.