S1898 Human Immunodeficiency Virus Co-Infection and Cancer Risk in Inflammatory Bowel Disease: Results From a Large National Database

Introduction: Recent data suggest that inflammatory bowel disease (IBD) in people living with HIV (PLWH) often follows a less aggressive course and is managed with fewer advanced therapies. Both HIV infection and IBD independently increase cancer risk, yet it is unclear whether the combined burden further amplifies that risk. Methods: We queried the U.S. TriNetX collaborative network (comprising >100 million patient records). Using International Classification of Diseases 10 codes, we identified Adults (≥18 y) with ≥3 IBD encounters who received an IBD therapy. We compared IBD in PLWH compared to IBD alone. A propensity score matching (PSM) was performed for age, sex, race, and key comorbidities. Outcomes included risks of colorectal or anal cancer, colorectal cancer alone, anal cancer, anal cancer or dysplasia, colectomy, and risk of skin cancers. Hazard ratios (HR) with corresponding 95% confidence intervals were estimated; P value < 0.05 suggested statistical significance. Results: After PSM, 1,329 patients were included in each group. The median follow-up duration was 1,425 days in the IBD-HIV cohort, compared to 1,610 days in the controls. HIV co-infection was not associated with higher hazards of combined colorectal or anal cancer (HR 1.30, 95% CI 0.84–2.03, P = 0.22) or colorectal cancer alone (HR 1.10, 0.68–1.78, P = 0.41). In contrast, anal cancer (HR 4.80, 1.82–12.61, P = < 0.001) and anal cancer or dysplasia risks (HR 11.54, 6.53–20.39, P = 0.007) were markedly increased. Colectomy occurred less often with HIV (HR 0.52, 0.32–0.85, P = 0.008). Cutaneous melanoma/skin cancer risk did not differ (HR 1.43, 0.92–2.23, P = 0.63). Conclusion: In this large, matched cohort, HIV did not increase colorectal cancer risk in IBD but was strongly associated with anal cancer and anal dysplasia while appearing protective against colectomy. These findings argue for better screening strategies in PLWH with IBD while maintaining standard colorectal dysplasia screening. Prospective studies are needed to clarify the mechanisms underlying these observations and to verify whether the relatively milder IBD course activity in PLWH persists long term. Limitations of this study include the retrospective nature, reliance on International Classification of Diseases codes, and potential for residual confounding. Thus, further research is warranted to validate these findings. Disclosure: Supervised AI assisted with table generation but not data analysis.