Professor Steve Halligan and colleagues from the United Kingdom examined the use of CT colonography in the English Bowel Cancer Screening Programme (BCSP), and investigated detection rates.
Retrospective analysis of routinely coded BCSP data.
Guaiac fecal occult blood test-positive screenees undergoing CT colonography from 2006 to 2012 as their first-line colonic investigation were included.
Abnormalities found at CT colonography, subsequent polyp, adenoma and cancer detection and positive predictive value were calculated.
Detection rates were compared with those observed in positive test screenees investigated by colonoscopy.
The team reported that 2731 screenees underwent CT colonography.
The team suspected colorectal cancer or polyps in 38% of individuals.
The researchers reported that on confirmatory testing, 5% of screenees had colorectal cancer, and 20% had polyps, of which 17% were adenomatous.
|Advanced neoplasia was detected in 33%|
Overall detection was 24% for colorectal cancer or polyps, and 22% for colorectal cancer or adenoma.
Advanced neoplasia was detected in 19% of screenees.
The researchers found that positive predictive value for colorectal cancer or polyp was 72%.
By comparison, 9% of 72,817 screenees undergoing colonoscopy had cancer, and 51% had polyps.
Advanced neoplasia was detected in 33%.
The team observed that CT colonography detection rates and postive predictive value were higher at centers with experienced radiologists, and at high-volume centers.
The researchers noted that centers using 3-dimensional interpretation detected more neoplasia.
Professor Halligan's team concludes, "In the BCSP, detection rates after positive guaiac fecal occult blood test are lower for CT colonography than colonoscopy, although populations undergoing the two tests are different."
"Centers with more experienced radiologists have higher detection and accuracy."
"Rigorous quality assurance of BCSP radiology is needed."