ABSTRACT
Introduction Faecal immunochemical test (FIT) has been introduced as an effective screening test for colorectal cancer in the general population and colonoscopy is the gold standard test for confirmation of colon cancer. Due to the emergence of the SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) pandemic, endoscopy services were severely reduced to emergency only in order to minimise COVID-19 infection spread throughout the world. Subsequently, FIT has been used as a triage tool to refer urgently (2 week wait cancer pathway) along with other alarm symptoms, e.g. anaemia, weight loss and change in bowel habit;to endoscopy services in the UK. The aim of this study was to determine the diagnostic efficacy of FIT in colorectal disease within a London based district general hospital. Secondary aims including assessing whether FIT has any diagnostic efficacy in inflammatory bowel disease (IBD). Methods From March to December 2020 all cases referred to the 2 week wait cancer pathway were analysed. The FIT score as well as well as presenting alarm symptoms were recorded prior to further investigation. The post colonoscopy outcome was also recorded to assess which patients were diagnosed with Colo-rectal cancer. Results There were 386 cases referred under 2 weeks wait cancer pathway. Of them 137 had positive FIT (>10 microgram/gram). Only 12 of those had colorectal cancer diagnosed on colonoscopy (8.8%). Median age of 68.5 (the range 44- 90 years), 58 % female and 42% were male respectively. The sensitivity of FIT in colorectal cancer diagnosis was 90% with a specificity of 48%, positive predictive value (PPV) was 6% and negative predictive value (NPV) 99%, However, out of 137 FIT positivity, there were 14 cases diagnosed inflammatory bowel disease (IBD, 13 Ulcerative colitis and 1 Crohn's disease). The sensitivity of FIT in diagnosing IBD was 93%, and specificity was 49% The PPV is 8% and NPV 99%. The Median age 56 (range 25-82 years), 57% were male and 43% were female. Those with a positive FIT and new IBD diagnosis appeared to be a younger, male dominant group. Conclusion FIT is a useful Colo-rectal cancer screening tool within the general population though its diagnostic yield is low. Its use has dramatically increased throughout the pandemic allowing a release of pressure off 2 week wait services with fewer referrals in FIT negative patients. Using FIT as a rule out method should be approached with caution as it is clear some Colo-rectal malignancies can present as FIT negative. FIT may also have a potential in assisting the diagnosis of IBD, in particular ulcerative colitis, within a younger group of the population though remains inferior to faecal calprotectin. Judicious use of the FIT in specific age groups is recommended in order to minimise both patient and practitioner anxiety and unnecessary referral.