Detection of advanced colorectal neoplasia and relative colonoscopy workloads using quantitative faecal immunochemical tests: an observational study exploring the effects of simultaneous adjustment of both sample number and test positivity threshold

Abstract

ObjectiveWhen screening for colorectal cancer (CRC) using quantitative faecal immunochemical tests (FIT), test parameters requiring consideration are the faecal haemoglobin concentration (f-Hb) positivity cut-off and the number of stools sampled. This observational study explored variation in f-Hb between samples and the relationship between sensitivity for advanced neoplasia (AN, cancer or advanced adenoma) and colonoscopy workload across a range of independently-adjusted parameter combinations.DesignQuantitative FIT data (OC-Sensor) were accessed from individuals undergoing personalised colonoscopic screening with an offer of 2-sample FIT in the intervening years. We estimated variation in f-Hb between samples in 12 710 completing 2-sample FIT, plus test positivity rates (colonoscopy workload) and sensitivity for AN according to parameter combinations in 4037 instances where FIT was done in the year preceding colonoscopy.ResultsThere was large within-subject variability between samples, with the ratio for the second to the first sample f-Hb ranging up to 18-fold for all cases, and up to 56-fold for AN cases. Sensitivity for AN was greatest at lower f-Hb cut-offs and/or using 2-sample FIT. Colonoscopy workload varied according to how parameters were combined. Using different cut-offs for 1-sample FIT and 2-sample FIT to return similar sensitivity, workload was less with 2-sample FIT when the sensitivity goal exceeded 35%.ConclusionVariation in f-Hb between samples is such that both parameters are crucial determinants of sensitivity and workload; independent adjustment of each should be considered. The 2-sample FIT approach is best for detecting advanced adenomas as well as CRC provided that the colonoscopy workload is feasible.

Prioritisation of colonoscopy services in colorectal cancer screening programmes to minimise impact of COVID-19 pandemic on predicted cancer burden: A comparative modelling study

“…We have shown that modification of the FIT threshold is one possible approach to mitigate the impact of the disruption given colonoscopy constraints, as it would prioritise individuals at higher CRC risk. 10 , 11 As with any risk-based approach to screening, especially within an established, organised population screening programme, careful consideration of the local context is required. In the Netherlands, the FIT threshold has previously been modified within the national programme 25 and this could thus be considered a relatively easy option to ensure the continuity of CRC screening in the case of colonoscopy constraints.…”

“…The COVID-19 and Cancer Global Modelling Consortium (CCGMC; www.ccgmc.org ) was established to support decision making in cancer control both during and after the COVID-19 crisis. This study's objective, conducted as part of the CCGMC, focussed on two example approaches to colonoscopy prioritisation: increasing the FIT threshold for referral to diagnostic colonoscopy, so capacity is directed towards those at higher risk, 10 , 11 and extending the recovery period in which missed individuals are caught up, resulting in extension of the screening interval for a larger proportion of the population. A combination of both approaches would also be possible, allowing for a careful trade-off between managing colonoscopy demand and preventing COVID-19-related excess CRC-related deaths.…”

Reducing the need for colonoscopy with adjusted FIT and FOBT for stool weight and serum Hb levels

“…Research has shown that the accuracy of FIT and FOBT in stool samples can vary from day to day. This variation can be attributed to several factors, including differences in the intensity of bleeding from the neoplasm daily ( 6 ). We have put forth another possible explanation for the observed fluctuation: Daily stool weight can influence the precision of FIT and FOBT.…”

An efficient strategy for evaluating new non-invasive screening tests for colorectal cancer: the guiding principles

“…High diagnostic sensitivity may also result in a higher burden of surveillance colonoscopies. 40 See online supplemental material 6.2 for further discussion on the challenges of predicting incidence reduction from precursor detection.…”