Comparative analysis of gene mutations present in rectal mucus sampled using the OricolTM and DNA retrieved from the Paired Formalin-Fixed Tumour Blocks. Early Data from the OricolTM EGI-02 Study (2022)

Type of publication:
Conference abstract

*Lacy-Colson J.

Colorectal Disease. Conference: Association of Coloproctology of Great Britain and Ireland Annual Meeting. Edinburgh United Kingdom. 24(Supplement 2) (pp 15), 2022. Date of Publication: September 2022.

Background: The Colorectal 2-week wait (2WW) pathway is overwhelmed. qFiT has been added to the pathway, however cancer detection rate remains low ~5%. Using a novel rectal mucus sampling device (OricolTM) we hypothesized that shed genetic material could be retrieved from rectal mucus using OricolTM, potentially forming an accurate triage tool for colonoscopy or other investigation (Oricol EGI-02 Study). Method(s): The OricolTM device was used in symptomatic patients recruited from 4 NHS Trusts. DNA from FFPE-histology blocks was compared to the pre-operative OricolTM rectal mucus specimen. Using targeted next generation sequencing (NGS) incorporating error suppression technology, including unique molecular indexes (UMI's) and dual indexes (UDI's) for removal of PCR/sequencing errors/index hopping events, we assessed the single nucleotide polymorphisms (SNPs) present in 50 known CRC genes across both samples. Current recruitment to the Oricol-EGI- 02 Study is 586/600. 35 paired samples and 35 Oricol samples from normal 2WW colonoscopies were evaluated. Result(s): There were no statistical differences between tumour associated SNP burden in the FFPE-blocks and the rectal mucus sample from CRC patients. Tumour associated SNP burden in the paired cancer samples was significantly higher compared to the normal group (p < 0.001). Identical SNPs were identified in both tumour and paired Oricol samples. Conclusion(s): This result confirms the hypothesis that shedding of DNA from colorectal cancers (caecum to rectum) can be detected in rectal mucus using OricolTM. Sampling rectal mucus could be used to accurately detect CRC in unprepared patients, dramatically reducing the number of normal colonoscopies which currently overwhelm the 2WW pathway.

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