Incidence of intestinal & extra-intestinal cancers among individuals with Crohn's disease in northern India.

Background & objectives Crohn's disease (CD) is associated with a higher risk of malignancy, which is attributed to disease behaviour and the usage of immunosuppressants. The burden of malignancy in CD is scarcely reported from Asia. We report real-world data on CD-related malignancy from a northern Indian cohort. Methods This retrospective analysis included individuals with CD who were followed up at the All India Institute of Medical Sciences, New Delhi, from 2005 to 2021. The standardized incidence ratio (SIR) was used to calculate the relative risk of malignancy in CD affected individuals compared to the general population. Results In this study, 952 study participants were included, with a mean age at diagnosis of 36.9±15.11 yr; 61.1 per cent were male. The median follow-up duration was 34 months [IQR (interquartile range): 19-73]. Most study participants received steroids (76.7%), immunomodulators (68.7%), or anti-TNF therapy (10.8%). The overall incidence of malignancy was 1.05 per cent, indicating a 10.45 times higher risk in CD [SIR: 10.45; 95% Confidence interval (CI):4.98-17.96]. Eight out of 826, 1 of 106 and 1 of 25 study participants developed malignancy in the first, second and third decades, respectively. The cumulative risk of malignancy was 2.7, 5.5, and 13.4 per cent in the first, second, and third decades, respectively. Regarding bowel malignancies, one study participant each developed ileocaecal adenocarcinoma, anorectal adenocarcinoma, malignant rectal fibrous histiocytoma, and gastric adenocarcinoma. Extraintestinal malignancies included single cases each of follicular neoplasia of the thyroid, neuroendocrine tumour of the pancreatic tail, breast cancer, hepatocellular cancer, oral cancer, and prostate cancer. No cases of lymphoma or skin malignancy were reported. Interpretation & conclusions At 30 yr, the cumulative risk of malignancy among Indian CD-affected individuals was 13.4 per cent, with a SIR of 10.45 (95% CI: 4.98- 17.96). The risk increased with increasing age at disease onset and duration.