Family cancer burden may matter more than age in IBD

Clinical takeaway: Document both the number of first-degree relatives with colorectal cancer (CRC) and their age at diagnosis in patients with inflammatory bowel disease (IBD); two or more affected relatives may warrant an individualized surveillance discussion, although guidelines have not yet changed.

Current international guidance emphasizes having a first-degree relative diagnosed before age 50, but evidence in contemporary IBD populations has been limited. These findings suggest the overall family cancer burden may be a more informative risk marker.

The Swedish registry study included 124,387 patients with IBD and 1,213,641 matched general-population comparators followed for a median of 11 years from 1996 through 2023. Investigators recorded 1,882 CRC events in the IBD group and 14,177 among comparators, corresponding to incidence rates of 1.17 and 0.88 cases per 1,000 person-years, respectively.

Among patients with IBD, CRC incidence was 1.15 cases per 1,000 person-years without a family history and 3.84 with at least two affected first-degree relatives. After adjustment, having two or more affected relatives was associated with a 159% increase in CRC incidence and 2.69 additional cases per 1,000 person-years.

By contrast, having a first-degree relative diagnosed before age 50 was associated with a smaller, less precise 47% increase and 0.42 additional cases per 1,000 person-years. Absolute CRC rates within family-history categories were broadly similar for people with and without IBD; the exception was participants without a family history, among whom incidence was 41% higher with IBD.

The findings suggest that future risk-stratified surveillance approaches may benefit from considering the number of relatives affected by CRC, not just the age at diagnosis of a single relative. As senior author Ola Olén noted, “This raises the question of whether the number of affected relatives should carry greater weight when assessing cancer risk.”

Source: Everhov ÅH, et al. (2026 Sep 3) Gastroenterology. Impact of Family History on Colorectal Cancer Risk in Inflammatory Bowel Disease and in Matched General Population Comparators