Rates and characteristics of postcolonoscopy colorectal cancer in the Swedish IBD population: what are the differences from a non-IBD population?

OBJECTIVE: The rate of postcolonoscopy colorectal cancer (PCCRC) is considered a key quality indicator of colonoscopy; little is known about PCCRC in IBD. DESIGN: A population-based cohort study of colonoscopies in Sweden from 2001 to 2010 was conducted. Individuals with a colorectal cancer (CRC) detected within 36 months after a colonoscopy were identified and stratified on UC, Crohn's disease (CD) or non-IBD. The CRCs were classified as detected CRCs (dCRC) (0-6 months) or as PCCRCs (6-36 months). PCCRC rates were calculated by the number of false negative/(the number of true positive+the number of false negative) colonoscopies. Poisson regression analysis was employed to examine the association between PCCRC and IBD (CD and UC) diagnosis, age, gender, location, time period and comorbidities. RESULTS: We identified 348 232 colonoscopies in 270 918 individuals. Of these, 27 123 were performed on 14 597 individuals with CD, and 51 572 were performed on 26 513 individuals with UC. There were 13 317 CRCs in the non-IBD group, 133 in the CD group and 281 in the UC group. The PCCRC rate in the CD group was 28.3% and 41.0% in the UC group. The RR for a PCCRC was 3.82 (95% CI 2.94 to 4.96) in CD and 5.89 (95% CI 5.10 to 6.80) in UC, compared with non-IBD. The highest risk was observed among rectal cancer location in CD and in younger individuals with UC. CONCLUSION: The high rates of PCCRC in young patients with UC and for rectal cancer location in CD might affect future performance of IBD surveillance.

Post-endoscopy colorectal cancer after colectomy in inflammatory bowel disease patients: a population-based register study.

OBJECTIVES: Long-standing inflammatory bowel disease (IBD) colitis is an indication for endoscopic surveillance. Postcolonoscopy colorectal cancer (PCCRC), cancer detected after a negative colonoscopy, is a quality indicator for colonoscopy. In analogy with PCCRC, we aimed to assess postendoscopy CRC (PECRC) in individuals with IBD who had undergone colectomy. METHODS: This register study included Swedish adults with an IBD diagnosis who had undergone colectomy and later were examined by either colonoscopy or sigmoidoscopy during 2001-2012. The final study population had a CRC diagnosis within 36 months of the index examination. Poisson regression was used to assess the relative risks (RR) of PECRC. RESULTS: A total of 33 individuals, 12 with an ileorectal anastomosis and 21 with a rectal remnant, had a CRC diagnosis within 36 months of the index endoscopy. Eleven cancers were detected as CRCs, and 22 (67%) were PECRCs. Compared with individuals aged >70 years, individuals aged <30 years had an RR of 3.1 (P = 0.054) and individuals aged 30-50 years had a RR of 2.6 (P = 0.030). A longer interval between colectomy and index endoscopy (>10 vs. <10 years) was associated with a lower risk of PCCRC (RR = 0.5; P = 0.007). There was no significant difference between the risk for Crohn's disease vs. ulcerative colitis, or between ileorectal anastomosis and rectal remnant risks. CONCLUSIONS: Continuous surveillance of IBD patients after colectomy is important. In the postcolectomy context, PECRC may be used as a quality indicator.

Post-colonoscopy rectal cancer in Swedish patients with Crohn's disease 2001-2015: a population-based case review study.

OBJECTIVE: Post-colonoscopy colorectal cancer (PCCRC) is a key quality indicator of colonoscopy, and PCCRC rates are high in the IBD population. Rectal cancer, an important risk factor for PCCRC among patients with Crohn's disease (CD), has not previously been examined. METHODS: Swedish adult patients with CD who underwent a colonoscopy within 36 months before a rectal cancer diagnosis between 2001 and 2015 were identified through the National Patient and Cancer registers. Their medical records were reviewed and a root-cause analysis and a sub-categorization according to the World Endoscopic Organization (WEO) were performed. RESULTS: Of 24 patients with CD and PCCRC in the rectum, 79% were men and the median age was 50 (IQR 45-59) years. The median disease duration was 21.5 (IQR 19-30) years. The cancer was located in the distal 5 cm of the rectum in 63% of the cases. Retroversion in the rectum was reported in only one case. The most common plausible explanation for PCCRC was 'possible missed lesion, prior examination adequate' (63%); when adding retroversion in the rectum, instead 77% of examinations were considered negative but deemed as inadequate. The most common PCCRC sub-category was non-interval type C (54%) and B (37%). Among those with type C, 38% should have been included in surveillance according to present guidelines. CONCLUSION: Better adherence to surveillance guidelines and more meticulous follow-up is warranted. The importance of performing rectal palpation and retroversion in the rectum is underscored and we suggest that this is included in the WEO algorithm.