Inflammatory bowel disease tied to increased risk of small bowel cancer
There appears to be an increased relative risk of small bowel adenocarcinomas in Crohn’s disease (CD) and of small bowel neuroendocrine tumours in both CD and ulcerative colitis (UC), a study suggests.
Researchers followed 20,917 patients with CD (median age at diagnosis 45 years; 57 percent female) and 42,872 patients with UC (54 percent female)—who were aged ≥16 years and living in Denmark during 1978 to 2010—for 241,600 and 417,600 person-years, respectively. Forty cases of inflammatory bowel disease (IBD)-associated small bowel cancer (SBC) were identified during follow-up via linkage between national registers and subsequent scrutiny of medical records and pathology descriptions.
Among patients with CD, 23 had small bowel adenocarcinoma and nine had neuroendocrine tumours, with corresponding standardized incidence ratios (SIRs) of 14.38 (95 percent CI, 8.78 to 22.20) and 6.83 (3.13 to 12.97).
Among patients with UC, 23 had neuroendocrine tumours (SIR, 2.63; 0.96 to 5.72). One patient had a duodenal adenocarcinoma and another had sarcoma, with the corresponding SIRs not significantly different from what was expected.
In terms of clinical characteristics, majority of patients with SBC had moderate-to-severe CD with small bowel and upper gastrointestinal involvement. Surgical specimens of small bowel adenocarcinomas revealed a transparent transition from inflammation to dysplasia and cancer, while none of the tumours showed evidence of microsatellite instability.
Researchers noted that adenocarcinomas of the small bowel occur in IBD-affected areas and follow a classical inflammation-dysplasia-cancer sequence, similar to IBD-related colorectal cancer (CRC), but this is not the case for NETs.
“The molecular features of IBD-related small bowel adenocarcinomas are not identical to those of IBD-related CRC and, hence, merit further investigation,” researchers added.