, shows a Danish population-based cohort study.
These findings suggest that more intensive long-term surveillance is needed for colectomized patients with IBD, wrote researchers who were led by Tine Jess, MD, DMSc, of the Center for Molecular Prediction of Inflammatory Bowel Disease, Aalborg University, Copenhagen.
“Our nationwide population-based cohort study covering 4 decades shows that despite a relatively low absolute number of RC cases following colectomy for IBD, the risk of RC is markedly increased 10 years after the surgery. This calls for better long-term surveillance of colectomized IBD patients,” the authors wrote in Gastro Hep Advances.
Previous studies have suggested that patients with IBD have an increased risk of rectal cancer after colectomy, but these data “cannot stand alone,” and “need to be confirmed in other unselected patient cohorts,” investigators wrote.
The new study was based on an analysis of data from more than 9 million individuals in the Danish Civil Registration System between 1978 and 2018. The analyses were restricted to risk of rectal cancer in the population with diverted rectum.
The final dataset included 4,931 patients with IBD who had subtotal colectomy and diverted rectum, 49,251 matched patients with IBD who did not undergo colectomy, and 246,550 matched individuals without IBD to serve as a background population. Within these groups, rectal cancer occurred at a rate of 0.9%, 0.4%, and 0.4%, respectively, hinting at an increased risk of rectal cancer after colectomy among patients with IBD.
This signal was clarified by comparing rates of rectal cancer 10 years before and after colectomy. Rates 10 years before colectomy were not significantly different between groups.
Comparing colectomized IBD patients with the noncolectomized IBD patients at the 10-year postcolectomy mark revealed an eightfold increased risk of rectal cancer (hazard ratio, 7.56; 95% confidence interval, 5.21-10.86). Risk was slightly lower for patients with Crohn’s disease (HR, 5.10; 95% CI, 2.41-10.81) than for those with ulcerative colitis (HR, 9.42; 95% CI, 6.18-14.36).
A comparison at the same time point for colectomized IBD patients versus the background population showed an even higher relative risk for rectal cancer, up 10-fold (HR, 10.01; 95% CI, 7.20-13.94).
Despite variations in surgical methods, researchers concluded that the long-term risk of rectal cancer post colectomy increased among patients with IBD.
The findings should inform surveillance guidelines, they wrote.
“To reduce the risk of CRC in IBD, endoscopic surveillance guidelines have been developed both nationally and internationally. However, guidelines do not include clear recommendations for patients with a residual rectum, ileo-rectal anastomosis, or ileal pouch-anal anastomosis. The Danish guidelines, the Danish Society of Gastroenterology and Hepatology, mention a potential increased risk of rectal cancer post colectomy ... The European Crohn’s and Colitis Organization guideline consensus paper ‘European Evidence-based Consensus: Inflammatory Bowel Disease and Malignancies’ mentions that ‘the risk of rectal cancer is relatively high in IBD patients after subtotal colectomy’ [but] without further recommendation,” study authors wrote.
The study was supported by Laege Carl Emil Friis, Hustru Olga Doris Friis, and the Danish National Research Foundation. The investigators disclosed no conflicts of interest.
