Comparison of faecal calprotectin using two collection and extraction strategies for the BÜHLMANN CALEX® Cap - possible implications for clinical cut-offs?

BACKGROUND: Faecal calprotectin has been identified as a useful biochemical marker in the differentiation of inflammatory bowel disease and irritable bowel syndrome. Typically, patients send faecal specimens in a pot for manual extraction by the laboratory. During the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS CoV-2) pandemic, the routine laboratory service was temporarily suspended due to the potential increased risk to staff. In this study we investigated the possibility of patients collecting samples directly into the faecal extraction tubes. METHOD: Patients submitted paired faecal samples for calprotectin analysis using a standard faecal container (current practice) and followed instructions for faecal collection using the BÜHLMANN CALEX® Cap device. Samples were returned to the laboratory immediately after collection. Laboratory staff manually extracted the calprotectin from the faecal samples using the CALEX® Cap prior to analysis of both extracts on the Cobas c702. RESULTS: 91 paired faecal samples were included in the study. Clinical correlation was found to be 70% with numerical correlation showing a positive bias for the patient-collected CALEX® Cap sample when compared to the laboratory-extracted faecal sample around the clinical decision points 100-250 µg calprotectin/g faeces. CONCLUSION: The study shows that collection of a faecal sample using the CALEX® Cap works well and is a good alternative to using standard containers. The correlation gives rise to the possibility that faecal calprotectin is not stable when collected into standard collection containers. Prior to further roll-out of this process, questions surrounding the current cut-offs would need to be addressed.

Microbiome Analysis of More Than 2,000 NHS Bowel Cancer Screening Programme Samples Shows the Potential to Improve Screening Accuracy.

PURPOSE: There is potential for fecal microbiome profiling to improve colorectal cancer screening. This has been demonstrated by research studies, but it has not been quantified at scale using samples collected and processed routinely by a national screening program. EXPERIMENTAL DESIGN: Between 2016 and 2019, the largest of the NHS Bowel Cancer Screening Programme hubs prospectively collected processed guaiac fecal occult blood test (gFOBT) samples with subsequent colonoscopy outcomes: blood-negative [n = 491 (22%)]; colorectal cancer [n = 430 (19%)]; adenoma [n = 665 (30%)]; colonoscopy-normal [n = 300 (13%)]; nonneoplastic [n = 366 (16%)]. Samples were transported and stored at room temperature. DNA underwent 16S rRNA gene V4 amplicon sequencing. Taxonomic profiling was performed to provide features for classification via random forests (RF). RESULTS: Samples provided 16S amplicon-based microbial profiles, which confirmed previously described colorectal cancer-microbiome associations. Microbiome-based RF models showed potential as a first-tier screen, distinguishing colorectal cancer or neoplasm (colorectal cancer or adenoma) from blood-negative with AUC 0.86 (0.82-0.89) and AUC 0.78 (0.74-0.82), respectively. Microbiome-based models also showed potential as a second-tier screen, distinguishing from among gFOBT blood-positive samples, colorectal cancer or neoplasm from colonoscopy-normal with AUC 0.79 (0.74-0.83) and AUC 0.73 (0.68-0.77), respectively. Models remained robust when restricted to 15 taxa, and performed similarly during external validation with metagenomic datasets. CONCLUSIONS: Microbiome features can be assessed using gFOBT samples collected and processed routinely by a national colorectal cancer screening program to improve accuracy as a first- or second-tier screen. The models required as few as 15 taxa, raising the potential of an inexpensive qPCR test. This could reduce the number of colonoscopies in countries that use fecal occult blood test screening.