Faecal immunochemical test: challenges and opportunities for cancer diagnosis in primary care

[摘要] Colorectal cancer (CRC) disproportionately causes the second highest number of UK cancer deaths (16 600 annually) as it has the fourth highest incidence.1 The UK has the lowest 1- and 5-year bowel cancer survival rates among the International Cancer Benchmarking Partnership countries,2 the majority of patients being diagnosed at late stage (III and IV). The incidence in those aged ≤50 years is increasing (particularly in 20–29-year-olds where incidence increased by 7.9% a year from 2004 to 2016).3Early-stage (I and II) bowel cancer confers 92% 5-year survival,1 and optimising faecal immunochemical test (FIT)-based bowel screening is vital to improve bowel cancer outcomes. An observational study found FIT-based screening programmes reduced participant bowel cancer mortality by 41%, dwarfing the 16% reduction demonstrated by guaiac faecal occult blood screening.4 Many GP practices are supporting bowel screening by systematically and/or opportunistically giving non-responders encouragement to participate.Endoscopy capacity has not kept pace with demand. The advent of bowel screening, the National Institute for Health and Care Excellence’s (NICE) lowering of referral thresholds (to attain early-stage diagnosis),5 and infection control restrictions/workforce levels due to the pandemic have all contributed to a crisis in endoscopy capacity. This could worsen as bowel screening uptake improves and eligibility is extended to those aged 50 years at a FIT positivity threshold of 80 µHb/g over the next few years.FIT ENDORSEMENT AND COVID-19 When NICE endorsed FIT,6 it was predicted that FIT could safely hone demand on colonoscopy services, identifying high-risk patients and providing them with earlier diagnosis while reassuring those at very low risk. Rollout of DG306 in the UK has been patchy and evaluation clouded by COVID-19 pathway changes.COVID-19 resulted in widespread adoption of FIT as a secondary care prioritisation tool, allocating precious endoscopy slots primarily to FIT-positive patients. This resulted in a large-scale natural experiment with very positive results. Modelling of FIT-based triage during COVID-19 concluded that it reduced mortality (attributable to presentation/diagnostic delay) by 89%.7Increasingly, we are seeing FIT being used as a rule-in test/downgrade tool for high-risk patients. In the absence of evidence-based national guidance, this can be concerning for GPs. Furthermore, despite FIT’s usefulness as a triage tool, FIT-based triage can result in delay and inefficient colorectal pathways — decisions are being deferred in the hope of receiving a FIT result; a positive FIT result, received after investigations have started, can lead to additional tests being deemed necessary.In short, despite FIT’s considerable potential to revolutionise early diagnosis of colorectal cancer, its absence at time of vetting is a source of frustration for triaging consultants, and the exclusion of NG12 criteria patients from urgent investigation because FIT is negative or absent is a source of frustration for GPs.

[学科分类] 卫生学