Use of Fecal Immunochemical Testing for Risk Stratification of Patients With Symptoms of Colorectal Cancer Referred for Diagnostic Colonoscopy

Cancer Referred for Diagnostic Colonoscopy F ecal immunochemical testing (FIT) is widely used in colorectal cancer (CRC) screening among asymptomatic individuals across many countries with varying cutoff values to select patients for colonoscopy. 1However, the implementation of FIT in symptomatic primary care patients is less prevalent among countries, most likely due to concerns about missed cancer diagnoses in these patients. 2The United Kingdom has now implemented FIT with a threshold of 10 mg hemoglobin (Hb)/g to risk-stratify symptomatic patients for their urgent cancer pathway (UCP). 3In Denmark, there is deliberation about implementing FIT in the same manner, however, the countries differ in several relevant aspects (Supplementary Figure 1).As of now, in the Danish UCP, all patients presenting with symptoms suspicious of CRC are mandated by law to receive a colonoscopy within 14 days, which causes serious strain on the endoscopy units. 4In Denmark, the consequence of this strain is perceived financially when colonoscopies need to be outsourced to private hospitals at the expense of the public hospitals in order to meet the 14-day deadline.The aim of this study was to investigate whether FIT can be used to select patients in the UCP in need of an urgent colonoscopy to reduce the number of colonoscopies performed without decreasing the CRC detection rate.This prospective observational study included patients from 4 university hospitals in the Capital Region of Denmark who were referred to UCP with symptoms of CRC from January 2019 to November 2021.Details on symptoms and outcomes can be found in the Supplementary Material.FIT was determined before bowel cleansing preparation prior to colonoscopy.RStudio software, version 4.3.0 5 was used for statistical analysis.Areas under the curve of the receiver operating characteristics were calculated for FIT.The following 3 cutoff values were chosen: >7 mg Hb/g, 10 mg Hb/g, and 20 mg Hb/g, representing the following scenarios, respectively: lowest measurable FIT outcome, FIT threshold recently introduced for symptomatic patients in the United Kingdom, and current FIT threshold used in the Danish population-based CRC screening.Among 1718 participants, 118 were excluded on the basis of missing FIT results (n 92) or missing diagnostic follow-up (n 26).A total of 1600 individuals with complete data were included for the final analysis.CRC was found in 79 (5%) of the 1600 participants by means of colonoscopy, pathology, or imaging.FIT as a continuous numerical test had an area under the curve of 0.88 (95% CI, 0.84-0.92)for CRC detection.Increasing the FIT cutoff resulted in lower sensitivity and higher specificity (Table 1).Using an FIT cutoff of 10 mg Hb/g