[Early diagnosis of colorectal cancer: technical problems and acceptability]

There has been little change in the survival rate of colorectal cancer over the last 20 years. Earlier diagnosis probably offers the best hope for improving this survival. At the present time, the only practical method of population screening is by the detection of occult blood in the faeces. Almost all published screening trials are uncontrolled. Although cancer detected by occult blood screening tends to be at a relatively early stage, only controlled trials can answer the critical question of whether screening decreases mortality from bowel cancer. High risk patients (prior adenoma or colorectal cancer, extensive colitis of more than 10 years duration, family history of polyposis) should have colonoscopy at regular intervals.