Evaluation of 13,466 Fecal Immunochemical Tests in Patients Attending Primary Care for High- and Low-Risk Gastrointestinal Symptoms of Colorectal Cancer

AIM/OBJECTIVE: Quantitative fecal immunochemical tests (FIT) were recommended by NICE for patients in primary care presenting with low-risk symptoms of colorectal cancer (CRC). FIT is more accurate in the detection of CRC than symptom criteria. Despite this, CRC still occurs with a negative FIT and the importance of safety netting for patients with severe or persistent symptoms is paramount. We aimed to evaluate the utilization and accuracy of FIT for CRC in low and high-risk symptom groups presenting to primary care, the effectiveness of safety netting in primary care, referral practices with FIT utilization for symptomatic patients and the clinical features of FIT negative patients with CRC. MATERIALS AND METHODS: Medical records and databases of all patients undertaking a FIT sample in the Herts Valleys CCG between June 2019 and November 2021 were reviewed. 13,466 consecutive FIT samples were requested for 12,231 patients between June 2019 and November 2021. RESULTS: Analysis of diagnostic accuracy was undertaken for the first 5341 patients with a minimum of 12 months follow up. Sensitivity for CRC, in FIT ≥ 4 µg Hb/g, ≥ 10 µg Hb/g and ≥ 100 µg Hb/g was 93% (95% CI 85–98%), 91% (95% CI 82–96%) and 72% (95% CI 60–81%) with a number needed to investigate of 36, 19 and 6, respectively. CONCLUSION: A FIT ≥ 10 µg Hb/g in conjunction with ongoing GP clinical concern within 8 weeks had a sensitivity for CRC of 97% (95% CI 90–100%), a PPV of 3.6% (95% CI 3.4–3.7%) and a number needed to investigate to detect one CRC of 28.