Double faecal immunochemical testing in patients with symptoms suspicious of colorectal cancer

Abstract

Background Faecal immunochemical test (FIT)-directed pathways based on a single test have been implemented for symptomatic patients. However, with a single test, the sensitivity is 87 per cent at 10 µg haemoglobin (Hb) per g faeces. This aims of this study were to define the diagnostic performance of a single FIT, compared with double FIT in symptomatic populations. Methods Two sequential prospective patient cohorts referred with symptoms from primary care were studied. Patients in cohort 1 were sent a single FIT, and those in cohort 2 received two tests in succession before investigation. All patients were investigated, regardless of having a positive or negative test (threshold 10 µg Hb per g). Results In cohort 1, 2260 patients completed one FIT and investigation. The sensitivity of single FIT was 84.1 (95 per cent c.i. 73.3 to 91.8) per cent for colorectal cancer and 67.4 (61.0 to 73.4) per cent for significant bowel pathology. In cohort 2, 3426 patients completed at least one FIT, and 2637 completed both FITs and investigation. The sensitivity of double FIT was 96.6 (90.4 to 99.3) per cent for colorectal cancer and 83.0 (77.4 to 87.8) per cent for significant bowel pathology. The second FIT resulted in a 50.0 per cent reduction in cancers missed by the first FIT, and 30.0 per cent for significant bowel pathology. Correlation between faecal Hb level was only modest (rs = 0.58), and 16.8 per cent of double tests were discordant, 11.4 per cent in patients with colorectal cancer and 18.3 per cent in those with significant bowel pathology. Conclusion FIT in patients with high-risk symptoms twice in succession reduces missed significant colorectal pathology and has an acceptable workload impact.

‘Low’ faecal immunochemical test (FIT) colorectal cancer: a 4‐year comparison of the Nottingham ‘4F’ protocol with FIT10 in symptomatic patients

“…In the absence of strong evidence, repeat FIT for those with initially negative results is inconsistent. Some benefited from repeat FIT in line with emerging data from other groups [21, 22]; a route to diagnosis in 10% of the patients with CRC but with repeat test detection rates <1%. Low FIT appears to detect early stage CRC in this dataset, over half with Stage I or II, despite the impact of false reassurance or diagnostic delays in some.…”

“…Low FIT appears to detect early stage CRC in this dataset, over half with Stage I or II, despite the impact of false reassurance or diagnostic delays in some. We now recommend more strongly a second FIT for those with fHb between 4 and 19.9 μg Hb/g faeces based on our findings and those from other centres [21, 22]. These areas require further study and validation.…”

“…The extremes of fHb have very strong predictive values (Figure 2 reassurance or diagnostic delays in some. We now recommend more strongly a second FIT for those with fHb between 4 and 19.9 μg Hb/g faeces based on our findings and those from other centres [21,22].…”

Do risk scores improve use of faecal immunochemical testing for haemoglobin in symptomatic patients in primary care?

“…One such approach may be to consider the value of repeat FIT. Sensitivity for CRC improves with a two FIT strategy where referral for bowel visualization is made when at least one FIT result is ≥10 μg Hb/g [27,28], although at the expense of a higher positivity. Further existing literature on repeat FIT strategies show two FIT results <10 μg Hb/g as an effective safety net for CRC [29,30].…”

Comment on: Double faecal immunochemical testing in patients with symptoms suspicious of colorectal cancer

“…We write regarding the recent paper by Gerrard et al . 1 , which was recently discussed at ‘CRAMSURG’, an online journal club based in the UK ( www.cramsurg.org ).…”