Crohn Disease Tied To Higher Colorectal Cancer Risk, Study Confirms

People with Crohn disease have an elevated risk of developing colorectal cancer, a Scandinavian population-based study confirms.

However, the risk was only increased in those diagnosed with the inflammatory bowel disease at earlier ages, researchers report in The Lancet Gastroenterology and Hepatology.

"Several previous studies have reported an increased risk of colorectal cancer in patients with Crohn disease, but these studies are older and have often shown uncertain risk estimates and as a consequence there are different approaches to surveillance for colorectal cancer in Crohn disease in different countries," Dr. Ola Olen of Karolinska Institutet, in Stockholm, told Reuters Health by email.

Dr. Olen and colleagues examined data from Denmark and Sweden spanning 1969 to 2017 and identified more than 47,000 patients and more than 460,000 matched controls from the general population.

There were 499 cases of incident CRC (0.82 per 1,000 person-years) in patients with Crohn disease compared with 4,084 cases in controls (0.64 per 1,000 person-years), yielding an adjusted hazard ratio of 1.40 (95% confidence interval, 1.27 to 1.53). Corresponding figures for CRC deaths were 296 and 1,968 (aHR, 1.74; 95% confidence interval, 1.54 to 1.96).

Thus, said Dr. Olen, "We can confirm that Crohn disease patients have an increased risk of being diagnosed with colorectal cancer and to die from colorectal cancer."

Importantly, he added, "among Crohn disease patients who are potentially eligible for colorectal-cancer surveillance we found that age of Crohn disease diagnosis is a currently overlooked factor. While we found a marked increased risk among patients diagnosed with Crohn's disease before age 40, we found no increased risk in the older age groups."

Another important finding, said Dr. Olen, "is that although colorectal cancer risk seems to have decreased over the last decades, there was still an increased risk of colorectal cancer in Crohn disease during the last 5 years of follow-up (2013-2017). During these last 5 years colorectal-cancer surveillance was recommended in certain subgroups of Crohn disease. We conclude that surveillance programs seem to be beneficial but they could likely still be improved."

Dr. Jason Ken Hou of Baylor College of Medicine, in Houston, Texas, who wrote an accompanying editorial, told Reuters Health by email, "Despite dramatic improvements in medical therapy for Crohn disease in the past two decades, mortality has not improved."

"Further research is needed to understand if more recent changes in medical approaches and colorectal-cancer screening will reduce cancer-related mortality in patients with Crohn disease," he added.

—David Douglas

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