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.