Diagnostic accuracy of faecal biomarkers in detecting colorectal cancer and adenoma in symptomatic patients.

BACKGROUND: The diagnosis of colorectal cancer (CRC) can be difficult as symptoms are variable with poor specificity. Thus, there is a quest for simple, non-invasive testing that can help streamline those with significant colonic pathology.

AIM: To assess using faecal immunochemical test for haemoglobin (FIT) or faecal calprotectin (FCP) to detect CRC and adenoma in symptomatic patients referred from primary care.

METHODS: A total of 799 referred for urgent lower gastrointestinal investigations were prospectively recruited. Of these, 430 completed colonic investigations and returned stool samples, and were included in the final statistical analysis. Faecal immunochemical test for haemoglobin was performed on HM-JACKarc analyser (Kyowa Medex, Tokyo, Japan), and FCP by the EliA Calprotectin immunoassay (Thermo Fisher Scientific, Waltham, United States).

RESULTS: The negative predictive value (NPV) using FIT alone or both markers (FIT and FCP) in combination was similar at 99% for CRC, with a sensitivity and specificity of 84% and 93%, respectively. FIT measurements were significantly higher in left-sided colonic lesions compared with the right side; 713 vs. 94; P = 0.0203). For adenoma, the NPV using FIT alone, or both markers (FIT and FCP) in combination, was similar at 94% with a sensitivity and specificity of 69% and 56%, respectively.

CONCLUSIONS: Undetectable faecal immunochemical test for haemoglobin is sufficiently sensitive to exclude colorectal cancer, with higher values in left-sided lesions. FCP in combination does not appear to provide additional diagnostic information. Further studies to determine the health economic benefits of implementing faecal immunochemical test for haemoglobin in primary care are required.