Chemical and immunological testing for faecal occult blood in screening subjects at risk of familial colorectal cancer.

BACKGROUND People with a family history of colorectal cancer have an increased risk of the disease themselves. Many centres are advocating family history screening by endoscopy. AIMS The performance of chemical and immunological faecal occult blood tests (Haemoccult and Hemeselect) in 212 subjects with a family history of colorectal cancer was assessed. RESULTS Both Hemeselect and Haemoccult were positive in the only patient with colorectal cancer. Hemeselect was more sensitive than Haemoccult for adenomas (40% compared with 20%) (adenomas larger than 1 cm 75% compared with 50%). No additional abnormality was detected by the addition of Haemoccult or Hemeselect to 60 cm flexible sigmoidoscopy in screening people at lower levels of familial risk. A false positive rate of 16% for Hemeselect resulted in a high proportion of additional colonoscopies in this group. CONCLUSIONS At present faecal occult blood tests are not sufficiently sensitive or specific to replace endoscopy in screening people at risk of familial colorectal cancer.