Fecal Immunochemical Test (FIT) in Triage of Bleed-positive (Crab+) and Bleed-negative Colorectal Adenoma (Crab-) Patients in Colorectal Neoplasia Screening

Abstract

Background/aim: Fecal immunochemical tests (FITs) are sensitive and specific for detecting colorectal cancer (CRC), but their diagnostic accuracy (DA) in bleed-positive (CRAb+) and bleed-negative colorectal adenomas (CRAb-) has been rarely tested.

Patients and methods: A total of n=506 patients were included in the study, each collecting 3 consecutive stool samples for analysis. The stool samples were analyzed by the ColonView FIT (CV) and Hemoccult SENSA tests. A total of 484/5,090 (9.5%) patients returned all 3 samples and were subjected to final analysis. Hierarchical summary receiver operating characteristic (HSROC) analysis with different cut-offs for hemoglobin/haptoglobin (Hb and Hb/Hp) complex was performed to assess the DA of CV.

Results: In the HSROC analysis, the AUC values were as follows: i) bleed-positive adenoma patients by visual analysis mode (VA), AUC=0.566, ii) bleed-positive adenoma patients by automatic analysis mode (AA), AUC=0.546, iii) bleed-negative adenoma patients by VA, AUC=0.534 and iv) bleed-negative adenoma patients by AA, AUC=0.589: In roccomp analysis, there were significant differences in AUC values between iii) and iv) p=0.045.

Conclusion: When stratified by the 'blood in stool' (as b+ or b- endpoint), the DA of the CV test is quite similar for CRAb+ and CRAb-. However, of the two modes (VA/AA) of the CV test, the AA reading gives a slightly higher DA both CRAb+ and CRAb-.

Keywords: Adenoma; FIT; blood in stool; fecal immunochemical test; screening.