• James Turvill, Samantha Mellen, Laura Jeffery, Sarah Bevan, Ada Keding, and Daniel Turnock.
• a Department of Gastroenterology , York Teaching Hospital NHS Foundation Trust , York , UK.
• Scand. J. Gastroenterol. 2018 Dec 1; 53 (12): 1526-1534.

BackgroundThe role of faecal biomarkers in patients at 'high risk' of colorectal cancer (CRC) is not yet defined. Pre-analytical factors, such as heterogeneity of biomarker distribution within faeces, may influence their optimisation in clinical practice. We undertook to determine whether repeat or combined biomarker testing improves diagnostic accuracy for CRC or clinically significant disease.MethodsPatients referred with suspected CRC provided two separate faecal samples each for faecal immunochemical testing (FIT) and faecal calprotectin (FC) prior to investigation. Diagnostic accuracy of FIT and FC were evaluated based on final diagnoses.ResultsFive hundred fifteen patients completed a full colorectal evaluation. The optimal cut-off for CRC using a single FIT was ≥12 µgHb/g faeces (84.6% sensitivity, 88.5% specificity). For two FIT, the cut-off was ≥43 µgHb/g faeces if either and ≥2 µgHb/g faeces if both were positive. There was no advantage in their diagnostic accuracy compared with a single FIT. FC had a lower diagnostic accuracy for CRC than FIT, which was not improved by repeat FC. No benefit was identified with FIT-FC combined. For CRC, significant adenomatous polyps and organic enteric disease combined, FIT and FC performed similarly to each other but were poorer predictors (AUC 0.677 and 0.660). There was no uplift in diagnostic accuracy when the tests were repeated or combined.ConclusionThis study supports using a single FIT at a cut-off close to that recommended by NICE DG30 to improve diagnostic accuracy for 'two-week wait' patients referred with suspected CRC.

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