CHEMICAL AND IMMUNOLOGICAL TESTING FOR FECAL OCCULT BLOOD IN SCREENING SUBJECTS AT RISK OF FAMILIAL COLORECTAL-CANCER

Background-People with a family history of colorectal cancer have an i ncreased risk of the disease themselves. Many centres are advocating f amily history screening by endoscopy. Aims-The performance of chemical and immunological faecal occult blood tests (Haemoccult and Hemeselec t) in 212 subjects with a family history of colorectal cancer was asse ssed. Results-Both Hemeselect and Haemoccult were positive in the only patient with colorectal cancer. Hemeselect was more sensitive than Ha emoccult for adenomas (40% compared with 20%) (adenomas larger than 1 cm 75% compared with 50%). No additional abnormality was detected by t he addition of Haemoccult or Hemeselect to 60 cm flexible sigmoidoscop y in screening people at lower levels of familial risk. A false positi ve rate of 16% for Hemeselect resulted in a high proportion of additio nal colonoscopies in this group. Conclusions-At present faecal occult blood tests are not sufficiently sensitive or specific to replace endo scopy in screening people at risk of familial colorectal cancer.