People with inflammatory bowel disease (IBD) who have several close family members diagnosed with bowel cancer appear to face a notably higher risk of developing the disease themselves, according to a large Swedish study. The findings suggest that current screening guidance, which focuses mainly on whether one relative was diagnosed young, may not fully capture how family history affects risk for people with Crohn’s disease or ulcerative colitis.
Background
People living with Crohn’s disease or ulcerative colitis already have a higher chance of developing bowel cancer, sometimes called colorectal cancer, than the general population. Family history is a well-recognised factor in this risk, but researchers have had limited data on exactly how having close relatives with the disease, such as parents, siblings or children, changes the picture for people who already have IBD.
What the study found
Researchers from Karolinska Institutet in Sweden used national health records to study more than 124,000 people with IBD between 1996 and 2023, comparing them with over 1.2 million people from the wider population. Everyone was followed for around eleven years on average, during which 1,882 people with IBD went on to develop bowel cancer.
The team reported that people with IBD who had two or more close relatives previously diagnosed with bowel cancer were around two and a half times more likely to develop the disease themselves, compared with those with IBD who had no such family history. By comparison, having just one close relative diagnosed with bowel cancer before the age of fifty was linked to a smaller increase in risk, of just under fifty per cent.
The researchers also noted that people with a close relative with bowel cancer had a broadly similar overall level of risk whether or not they had IBD, suggesting that family history itself carries a strong signal regardless of bowel disease status.
Why this matters
According to the study authors, current international guidance for people with IBD tends to focus on whether a parent, sibling or child was diagnosed with bowel cancer at a young age. This research suggests that the total number of affected relatives, not just their age at diagnosis, may be an important factor worth considering when thinking about future cancer screening for people with IBD. The researchers said this raises the question of whether screening recommendations should give more weight to family cancer burden overall.
What to keep in mind
This was an observational study using health registry data, meaning it can show a link between family history and bowel cancer risk but cannot prove that one directly causes the other. The researchers did not report on lifestyle, environmental or genetic testing factors that might also play a role. Any change to screening guidelines would need further research and review by clinical guideline bodies before being put into practice.
Practical takeaways
- Family history, including the number of close relatives affected, may be relevant to bowel cancer risk in people with IBD.
- This research does not mean anyone should change their current screening or monitoring plan without discussing it with their care team.
- People with IBD who have concerns about family history of bowel cancer may wish to raise this with their gastroenterologist.
- Further research is needed before guidelines are updated to reflect these findings.
Reference
Karolinska Institutet. Family cancer burden predicts risk in patients with inflammatory bowel disease. Published in Gastroenterology, 2026. Full citation details, including volume, page numbers and DOI, were not provided in the available source material; readers are advised to consult the Gastroenterology journal directly for the complete published article.
This article is a journalistic summary for informational purposes only. It does not constitute clinical advice or a recommendation to alter treatment decisions.