Population screening for colorectal cancer, the goals and means.

The causes of colorectal cancer are complex and in most cases obscure, making primary prevention impossible at present. Secondary prevention by finding and treating early asymptomatic cancers may possibly reduce mortality from this very common cancer. Results from conventional treatment have changed little during recent decades and are unsatisfactory, with more than half of the patients dying from the disease. The incidence has increased during recent years in many countries, making it vital to evaluate possible benefits from screening. This review considers different methods of screening for colorectal cancer and includes an overview of continuing European controlled randomised trials with the faecal occult blood test, Haemoccult-II. No final evaluation is possible, but advantages and drawbacks of different strategies are discussed. Assuming that the goal of reducing mortality is achieved, several other problems remain unsolved: the organisation of screening, the training of doctors in endoscopy, cost benefit and cost effectiveness all of which will have to be solved before a population screening can be recommended. Present screening tools are not ideal and we have to continue the search for better markers of early colorectal cancers and even possible precursors like adenomas.