Faecal immunochemical testing for haemoglobin in detecting bowel polyps in symptomatic patients: multicentre prospective cohort study

Diagnostic accuracy of the faecal immunochemical test and volatile organic compound analysis in detecting colorectal polyps: meta-analysis

BACKGROUND

For the early detection of colorectal cancer, it is important to identify the premalignant lesions to prevent cancer development. Non-invasive testing methods such as the faecal immunochemical test are well established for the screening and triage of patients with suspected colorectal cancer but are not routinely used for polyps. Additionally, the role of volatile organic compounds has been tested for cancer detection. The aim of this review was to determine the diagnostic accuracy of the faecal immunochemical test and volatile organic compounds in detecting colorectal polyps.

METHODS

Original articles with diagnostic test accuracy measures for both the faecal immunochemical test and volatile organic compounds for advanced adenomas were included. Four databases including Medical Literature Analysis and Retrieval System Online (MEDLINE), Cumulative Index to Nursing and Allied Health Literature (CINAHL), Embase, and Web of Science were searched. The quality assessment tool for diagnostic accuracy study was used to assess the risk of bias and applicability. Meta-analysis was performed using RStudio® and the combined faecal immunochemical test-volatile organic compounds sensitivity and specificity were computed.

RESULTS

Twenty-two faecal immunochemical tests and 12 volatile organic compound-related articles were included in the systematic review whilst 18 faecal immunochemical tests and eight volatile organic compound-related studies qualified for the meta-analysis. The estimated pooled sensitivity and specificity of the faecal immunochemical test to diagnose advanced adenoma(s) were 36% (95% c.i. 30 to 41) and 89% (95% c.i. 86 to 91) respectively, with an area under the curve of 0.65, whilst volatile organic compounds pooled sensitivity and specificity was 83% (95% c.i. 70 to 91) and 76% (95% c.i. 60 to 87) respectively, with an area under the curve of 0.84. The combined faecal immunochemical test-volatile organic compounds increased the sensitivity to 89% with a specificity of 67%.

CONCLUSION

Faecal immunochemical testing has a higher specificity but poor sensitivity for detecting advanced adenomas, while volatile organic compound analysis is more sensitive. The combination of both tests enhances the detection rate of advanced adenomas.

Diagnostic Performance of Faecal Immunochemical Testing (FIT) in Patients with Lynch Syndrome Scheduled for Colonoscopic Surveillance

BACKGROUND AND AIMS

Lynch syndrome (LS) carries a substantial lifetime risk of colorectal cancer which is currently mitigated by biennial colonoscopy surveillance. Paramount to the surveillance programme is the removal of adenomas before malignant transformation but there is an associated service burden and morbidity of repeated endoscopy. We investigated if faecal immunochemical testing (FIT) for faecal haemoglobin has the diagnostic performance to replace colonoscopy.

METHODS

In this retrospective cohort study, patients due to undergo planned surveillance for LS between November 2020 and April 2022 were sent two FIT kits prior to colonoscopy. Test diagnostic performance of colorectal cancer (CRC), advanced and non-advanced adenoma detection was calculated for single and double FIT strategies. A faecal-Hb of 10 µg Hb/g was considered positive.

RESULTS

In total, 78 patients, with 45 (57.7%) female, median age 52 years (IQR 41-63), completed at least one FIT and colonoscopy. The median time from FIT to colonoscopy was 47 days. A single FIT was positive in 7/30 cases of adenoma (2/3 advanced, 5/27 non-advanced). A total of 64 (82.1% of FIT1T returners) completed a second FIT. Using the greatest of the two FITs (FIT2TMAX) 8/26 (2/3 advanced, 4/23 non-advanced), patients with adenomas were identified. There were no cases of CRC. The sensitivity for adenoma detection was 23.3% and 23.1%, respectively.

CONCLUSIONS

In patients with LS awaiting colonoscopy, FIT has a low sensitivity for detecting adenomas and advanced adenomas. This is not improved by the addition of a second FIT test.

Diagnostic application of the ColonFlag AI tool in combination with faecal immunochemical test in patients on an urgent lower gastrointestinal cancer pathway

OBJECTIVE

Colorectal cancer (CRC) is the fourth most common cancer in the UK. Patients with symptoms suggestive of CRC should be referred for urgent investigation. However, gastrointestinal symptoms are often non-specific and there is a need for suitable triage tools to enable prioritisation of investigations. In this study, the performance of the faecal immunochemical test (FIT), anaemia and the artificial intelligence algorithm ColonFlag were retrospectively examined and evaluated for their potential clinical benefits in patients who had been referred on an urgent lower gastrointestinal cancer pathway.

DESIGN

All patients aged over 40 years referred in a 12-month period were included. After 6 months, clinical outcomes were determined and the performance of the triage tests was evaluated.

RESULTS

A total of 3822 patients completed investigations and received a diagnosis. 143 had CRC, 126 high-risk adenomas (HRA). ColonFlag would have missed 27 CRC and 29 HRA. Faecal haemoglobin (f-Hb) at a cut-off of 10 µg/g would have missed 10 CRC and 26 HRA; f-Hb in combination with anaemia would have missed 2 CRC and 14 HRA. Using f-Hb in combination with ColonFlag would have missed only 1 CRC and 5 HRA and would have reduced the need for urgent referral by over 400 patients.

CONCLUSION

ColonFlag has potential to assist detection of CRC and HRA, alone where no faecal sample is present and in combination with FIT and to reduce the need for urgent referral.