Attendance and diagnostic yield of repeated two sample faecal immunochemical test screening for colorectal cancer
Objective Limited data exist on attendance and additional yield of 2 sample faecal immunochemical testing (FIT) screening during multiple rounds. We therefore conducted a population based colorectal cancer screening trial comparing attendance and yield of repeated 1 sample and 2 sample FIT screenings. Design Two randomly selected groups of average risk subjects aged 50 74 years were invited for two rounds of either 1 sample (n=5007) or 2 sample (n=3197) FIT (OC sensor Micro) screening. The test was considered positive if at least one sample was positive (cut off 50 ng/mL; 10 ug haemoglobin/g) Results The cumulative attendance rate was similar for repeated 1 sample and 2 sample FIT screenings (1 sample FIT: 68.1% 2 sample FIT: 67.1% p=0.368) The positivity rate in the second round was lower for 1 sample FIT (6.2% 95% CI 5.4% to 7.2% than for 2 sample FIT (8.4% 95% CI 7.1% to 9.8% p=0.007) whereas the detection rate of advanced neoplasia (AN, 1 sample FIT: 1.9% 95% CI 1.2% to 2.2% 2 sample FIT: 1.7% 95% CI 1.2% to 2.5% p=0.861) and the positive predictive value (1 sample FIT: 32% 95% CI 24% to 40% 2 sample FIT: 21% 95% CI 15% to 29% p=0.075) did not differ. After two rounds of screening, the cumulative diagnostic yield of AN for 1 sample FIT was 29.3 per 1000 invitees, compared with 34.0 for 2 sample FIT (p=0.241) Conclusions Using 2 sample FIT instead of 1 sample FIT does not result in a higher detection rate of AN in the second round of repeated FIT screening. Furthermore, both strategies lead to a similar yield of AN over two rounds. These findings imply that 1 sample FIT screening is preferred over 2 sample FIT screening.
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