A brush-sampling fecal immunological test (FIT) is more accurate than a sensitive guaiac fecal occult blood test (GFOBT) for detecting colorectal cancer (CRC) and significant colorectal adenomas, conclude Australian researchers.
The FIT is an advanced form of fecal occult blood test that simplifies the logistics of stool sampling and thus reduces the barriers to population screening. Graeme Young, from Finders University of South Australia in Bedford Park, and colleagues therefore compared a sensitive GFOBT with a brush-sampling FIT.
In a cohort of 2351 individuals meeting the criteria for CRC screening and a symptomatic diagnostic group of 161 people, participants sampled consecutive stools at home using both the FIT and GFOBT sampling devices while following the dietary restrictions necessary for GFOBT.
Positivity rate comparisons for the two techniques were conducted in participants found to have CRC and/or significant adenoma (defined as high-grade dysplasia, villous change of 10 mm or more, serrated histology, or three or more polyps), benign pathology, or no pathology.
Combining screening and diagnostic groups, the results indicate that the FIT gave a true-positive result significantly more often than GFOBT for both CRC, at 87.5% versus 54.2%, and for significant colorectal adenomas, at 42.6% versus 23.0%. The FIT detected 12 of 13 Union Internationale Contre le Cancer stage I cancers, compared with four out of 13 for the GFOBT.
Further analysis of the screening cohort showed that the FIT remained significantly better than the GFOBT at detecting CRC and significant colorectal adenomas, While the false-positive rate was slightly higher for the FIT than the GFOBT for any neoplasia, at 3.4% versus 2.5%, the respective positive predictive values were 41.9% and 40.4%.
The team writes in the journal Cancer: "This brush-sampling FIT is significantly better at detecting advanced colorectal neoplasia than a sensitive GFOBT. Combined with behavioral advantages, such as where screening with FIT lead to a better participation rate, brush-sampling FIT can be predicted to deliver better reductions in CRC mortality and incidence than will GFOBT."