Screening for symptomless colorectal cancer by testing for occult blood in general practice.

1638 persons over the age of 45 were invited to test their faeces for occult blood, using the 'Haemoccult' method. The acceptance-rate was low (25%) in those over the age of seventy-five and was highest (56%) in those aged fifty-five to sixty. 3.8% of those using the test had at least one positive haemoccult test. Rigid sigmoidoscopy identified 2 persons with carcinoma of the rectum and 1 with adenoma of the rectum. Subsequent colonoscopy and barium enema identified two cases of adenoma of the sigmoid colon and one case of adenoma of the caecum.