Immunochemical fecal occult blood tests have shown a greater sensitivity than guaiac test in colorectal cancer screening, but optimal number of samples and cutoff have still to be defined.
Dr Grazzini and colleagues from Italy evaluated the performance of immunochemical-based screening strategies according to different positivity thresholds.
In addition, the research team examines single vs double sampling using 1-day sample with cutoff at 100 ng ml1 as the reference strategy.
A total of 20,596 subjects aged 50 to 69 years were enrolled from Italian population-based screening programs.
|The positivity rate was 8% for the most sensitive strategy|
|British Journal of Cancer|
Positivity rate was 5% for the reference strategy, and 8% and 2% for the most sensitive and the most specific strategy, respectively.
Cancer detection rate of reference strategy was 3, and ranged between 2 and 3 in other strategies.
The research team noted that the reference strategy detected 16 advanced adenomas.
The number needed to scope to find a cancer or an advanced adenoma was lower than 2 for the most specific strategies.
However, the team found that the number needed to scope to find a cancer or an advanced adenoma varied up to 3, according to different thresholds, for the most sensitive strategies.
Different strategies seem to have a greater impact on adenomas rather than on cancer detection rate.
Dr Grazzini and colleagues conclude, “The study provides information when deciding screening protocols and to adapt them to local resources.”