B13
DNA quantification of exfoliated colonocytes as a novel screening tool for colorectal neoplasia and inflammation
Adeel Bajwa1, Jacquie Peck1, Olagunju Ogunbiyi2, Romi Navaratnam3, Paul Boulos1, Austin Obichere1
1University College London Hospitals, London, UK, 2Royal Free Hopsital, London, UK, 3North Middlesex Hospital, london, UK
Background
Exfoliated colonocytes remain viable in the mucocellular layer lining the large bowel. The aim of this study was to evaluate a novel technique involving colonoycte retrieval from the rectal mucosa as a method of detecting colorectal cancer (CRC) and inflammatory bowel disease (IBD).
Method
A prospective double-blinded study. 236 consecutive patients referred with symptoms suggestive of CRC have so far been recruited. Exfoliated cells were collected from the rectal mucosa using an inflatable elastic membrane deployed with a proctoscope, during outpatient assessment. Samples were preserved in fixative before DNA isolation and quantification (Pico-Green assay). DNA scores were calculated blindly and compared with the outcome after subjects had completed endoscopic and radiological investigations. Samples that were heavily contacted with stool were excluded from analysis.
Results
57 of 236 were excluded due to; heavy faecal contamination (n=43); declined further investigations (n=6); unfit (n=3); inappropriate referral (n=5). 131 patients had lower GI endoscopy (colonoscopy=127, flexible sigmoidoscopy= 4); 45 patients underwent CT colonography and 3 had a barium enema. The diagnosis in all 179 patients were as follows; CRC (n=11), intermediate/high risk adenomatous polyps (AP)(n=8), IBD (n=6) and no significant abnormality detected (n=150). When a DNA score >1.63µg/mL was taken as a positive result, the combined sensitivity for detecting CRC, AP and IBD were 92% and 72.1% respectively.
Conclusion
In symptomatic patients, this technique has been shown to be highly sensitive with greater specificity for CRC than reported for faecal occult blood testing, and may hold promise as a more effective screening tool.
