Leading Edge 2022 Issue 2

14 LEADING EDGE - 2022-2 A Fitting Tribute: Judith Strachan is Presented with the 2022 ACB Foundation Award Faecal Immunochemical Testing – Past, Present and Future At the ACB UKMedLab22 Scientific Meeting, held at the Royal College of Pathologists in London in November 2022, Judith Strachan was presented with the prestigious Foundation Award. This accolade recognises her services to Clinical Biochemistry and, in particular, her work with the Scottish Bowel Screening Programme (SBoSP). In her plenary speech, “FIT for the Future (Past and Present too!)”, Judith discussed the changing demands on the laboratory, based on her experience working at NHS Tayside. Judith Strachan is a consultant clinical scientist at NHS Tayside and is also honorary senior lecturer at the University of Dundee. She has worked in the laboratory at NHS Tayside since 1990, and in that time has been instrumental in developing the services offered, to ensure the laboratory meets the ever-changing demands of the NHS. First Steps of Faecal Testing Faecal tests for haemoglobin, calprotectin, and elastase are now commonplace, most of which have specific sample collection devices designed to maximise uptake of the test, minimise pre-analytical variation and facilitate easy processing in the laboratory. However, as recently as the late 2000s, faecal testing was still in its infancy. A UK pilot study was conducted in 2000 to understand the efficacy of guaiac faecal occult blood tests (gFOBT) in population-based bowel cancer screening. Following the success of the study, the Scottish Bowel Screening Programme (SBoSP) was launched in 2007. The gFOBT screening kit included: an invitation letter, the test card, and return envelope. The screening cohort invited people between the age of 50 and 74, with those over 75 able to opt-in. Individuals are sent a test every two years. Reminders are issued if no response is received within six weeks, to encourage maximum participation. Using gFOBT, the programme had an uptake of around 50-55%, and a positivity rate of 2%. This programme continued for nearly ten years, and in this time, faecal testing began to evolve further. Scotland continued to pave the way for the advancements in faecal testing. The faecal immunochemical test (FIT) became the technology of focus for Judith and her colleagues, as it was hypothesised that this test could serve not only population-based screening but the triaging of symptomatic patients, who meet the diagnostic criteria for suspected colorectal cancer referral. FIT & Population-Based Screening In 2017, the SBoSP transformed its screening service by replacing qualitative gFOBT with quantitative FIT. This was no small task: it involved a laboratory refit, installation and work-up of four new analysers, staff training, redesign of the return mailer, revamping of the communications, and a review of the screening algorithm. Then there were the clinical hurdles to overcome; the increase in participation (uptake) was noticeable almost immediately. Increased Uptake Individuals who had never participated in screening previously were more engaged with FIT, and uptake rose from around 53%, to 64% in less than 12-months [Figures 1-4]. Then, there is the positivity to consider: for gFOBT this was around 2%, but FIT saw this rise to over 3%, with some cohorts seeing positivity closer to 5%. The increased sensitivity with FIT means that more people are being sent for colonoscopy than would have been previously when gFOBT was used in the screening programme. That said, FIT has been shown to catch more precancerous growths, and other significant bowel disease, when compared to its predecessor. This now changes the landscape for cancer diagnostics and is where screening and symptomatic could collide if not carefully managed. FIT in the Symptomatic Cohort Colorectal cancer is the third most common cancer in the UK, with over 42,000 cases and 16,000 deaths annually. Around 10% of all GP consultations are the result of gastrointestinal symptoms (Jones et al., Br J Gen Pract 2009), but these symptoms are often vague, unquantifiable, and poor predictors of underlying pathology (Jellema et al., BMJ 2010). FIT offered a way to help guide referral from primary care, whilst providing important information to gastroenterologists about the possible severity of the pathology, therefore facilitating more appropriate triaging. It is largely thanks to Judith and her colleagues that as of 2022, almost all of health boards in Scotland use FIT as part of their referral pathway for patients with suspected colorectal cancer and other significant bowel disease. Samples are sent to one of five laboratories in Scotland, all using the HM-JACKarc, system for analysis and GPs usually receive the FIT results via electronic test reporting systems.