Episode 193 - Colon Surveillance in Inflammatory Bowel Disease (IBD) with Dr Ali Eqbal
Patients with ulcerative colitis (UC) and Crohn's disease (CD) involving the colon are at an elevated risk of developing colorectal cancer (CRC), secondary to long-term chronic mucosal inflammation. The level of risk depends primarily on disease duration, the extent of colonic involvement, and the presence and grade of precancerous cell changes (dysplasia) present.
While most IBD patients never develop CRC, the risk, compared to the general population, is significantly higher. For ulcerative colitis, the cumulative risk is generally estimated as 1% to 2% at 10 years from diagnosis, 3% to 8% at 20 years since diagnosis, and 7% to 18% at 30 years' duration. The risk also depends on the severity and extent of the colitis.
For patients with Crohn's colitis, a level of CRC risk similar to those with UC is noted when comparable extents of large intestine inflammation are involved.
During colonoscopic surveillance of patients with IBD, dysplasia is looked for histologically, reflecting abnormal, precancerous cellular changes, and is categorised into low-grade (LGD) and high-grade (HGD) forms.
Patients with LGD are approximately 3.5 times more likely to develop advanced neoplasia compared to those without dysplasia, in the absence of intervention.
HGD is very dangerous. Approximately 40% of IBD patients with initial HGD findings on endoscopy will progress to colorectal cancer over a 15-year period if untreated.
Risk magnifiers include disease duration of 8 years or longer, colitis activity, and extent of disease involvement, including colitis that extends beyond the rectum into the left side of the colon or involves the entire colon (pancolitis).
Additionally, the presence of primary sclerosing cholangitis (PSC) complicating ulcerative colitis increases the CRC risk 4 to 5 times. (Between 70% and 80% of all patients who have PSC have ulcerative colitis, whilst 3% to 8% of all UC patients will develop it. By comparison, only 1% to 3.5% of Crohn's patients develop PSC.)
Due to these risks, guidelines recommend starting surveillance colonoscopies 8 to 10 years after symptom onset. The gold standard technique for dysplasia detection at endoscopy involves the engagement of high-definition chromoendoscopy, followed by targeted biopsies of visible lesions rather than relying solely on random biopsies.
Routine surveillance every 2 years helps identify dysplasia early, enabling proactive management and preventing progression to cancer.
Electronic filter techniques (virtual chromoendoscopy/NBI), combined with high-definition endoscopy, offer an alternative to chromoendoscopy and are superior to extensive random biopsies (previous recommendations requested 4 biopsies every 10 cm throughout the colon, aiming at detecting and locating flat, "invisible" dysplasia).
If PSC is diagnosed, annual colonic surveillance is recommended.
To discuss this subject in further detail, we are joined by Dr Ali Eqbal. Ali has expertise in advanced colonic interventional endoscopy and inflammatory bowel disease. He completed a two-year advanced endoscopy fellowship at King's College Hospital, London, where he developed expertise in the diagnosis and management of complex colonic polyps using techniques including endoscopic submucosal dissection (ESD) and endoscopic mucosal resection (EMR). He also undertook a clinical research fellowship in complex IBD at the Austin Hospital in Melbourne. He is widely respected and recognised for his advanced technical skills and commitment to minimally invasive treatment options. He has published and presented both nationally and internationally.
Please welcome Ali to the podcast.
References
Primary Sclerosing Cholangitis as an Independent Risk Factor for Colorectal Cancer in the Context of Inflammatory Bowel Disease: A Review of the Literature (PMC). Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC4112886/