Editorial: missed opportunities to detect colorectal cancer in inflammatory bowel disease—getting to the root

Abstract

Colorectal cancers (CRC) arising after a colonoscopy in which no cancer was found, so-called post-colonoscopy CRC (PCCRC), account for approximately 4% of all CRCs.1 Logically, patients at higher risk due to inflammatory bowel disease (IBD) require heightened attention to avoid PCCRC. Thus, various guidelines recommend an intensive colonoscopic surveillance protocol, and uniformly endorse yearly procedures in patients with IBD at highest risk.2 PCCRCs can arise as a consequence of missed cancers, missed or incompletely resected benign lesions, administrative issues (e.g., inadequate call-back systems) or patient-related factors (e.g., non-adherence). For each surveillance colonoscopy, the metrics for a high-quality exam should be achieved. With so many colonoscopies (theoretically) being performed for early detection of neoplasia in IBD, one might expect to find lower PCCRC rates, and a temporal decline in IBD-CRC incidence. Gordon et al found neither to be the case.3 They performed a root-cause analysis of CRC diagnoses among patients with IBD followed in a secondary care network between 1998 and 2019, utilising the PCCRC cause-identification framework developed by the World Endoscopy Organization.4 Among 78 patients with IBD-CRC, 42 met eligibility criteria for surveillance. Unfortunately, most patients had received either suboptimal or no surveillance. CRC was diagnosed on an overdue surveillance exam in 10%, and fully outside of surveillance in 64%. Two-thirds of the latter group were being managed by primary care; one-third had not received surveillance despite on-going secondary care follow-up. The remaining 26% of patients had received optimal surveillance, yet only 12% of CRCs were detected at a timely colonoscopy, whereas 14% were PCCRCs (found before the next recommended colonoscopy). The overall survival was similar between patients with IBDassociated vs sporadic CRC, but that analysis also included patients with IBD-CRC who were ineligible for surveillance. Over the past 20 years, there was no temporal decline in the incidence of either IBD-CRC corrected for IBD prevalence, or sporadic CRC corrected for their population. Surveillance in patients with IBD has unique issues. Colitisassociated CRC is often preceded by flat precursor lesions that are difficult to detect endoscopically.5 Invisible dysplasia (detected on random biopsies) is associated with higher risk of subsequent advanced neoplasia.6 PCCRCs in IBD are frequently preceded by a surveillance procedure with inadequate quality metrics, potentially leading to missed lesions.7 Background mucosal inflammation can obscure dysplastic lesions. Thus, surveillance should be performed with chromoendoscopy, or at least high-definition white light, to optimise dysplasia detection.8 Even when detected, complete resection of dysplasia may not be achieved in non-polypoid lesions and lesions >1 cm, further increasing the risk of developing CRC.6 Poor implementation of surveillance programmes is not a new observation and not specific to the UK.9 The study by Gordon et al reminds us about the importance of executing a robust, programmatic approach to IBD colonoscopic surveillance. Especially in this era where COVID-19 often greatly impacts the volume of endoscopic procedures being performed, patients with IBD at high risk must be prioritised to avoid the excess PCCRC seen all too often.