COMPARATIVE RISK OF LYMPHOMA IN PRIMARY SCLEROSING CHOLANGITIS PATIENTS WITH AND WITHOUT ULCERATIVE COLITIS: A PROPENSITY SCORE-MATCHED STUDY

Abstract BACKGROUND Primary sclerosing cholangitis (PSC) is associated with an elevated risk of malignancy, including lymphoma. Ulcerative colitis (UC), frequently comorbid with PSC, has also been linked to cancer risk through chronic intestinal inflammation and immunosuppressive therapy. Whether UC confers additional lymphoma risk in patients with PSC remains unclear. METHODS Patients with PSC, with and without UC, were identified in the TriNetX database using ICD-10 codes. Propensity score matching (1:1) was performed to adjust for confounders. The primary outcome was 5-year cumulative incidence of lymphoma (any type). Secondary outcomes included lymphoma subtypes, all-cause mortality, and hospitalization. Risk estimates were calculated using Kaplan–Meier methods and Cox proportional hazards models. RESULTS After matching, 4,212 PSC+UC patients were compared with 4,212 PSC-only patients. Over 5 years, the cumulative incidence of any lymphoma was 2.3% vs 1.9% (RR 1.19; 95% CI 0.89–1.59; p=NS). Non-Hodgkin lymphoma occurred in 1.4% vs 0.9% (RR 1.45; 95% CI 0.97–2.20), reflecting a nonsignificant trend toward increased risk with UC. Hodgkin lymphoma (0.2% vs 0.2%), T-cell lymphoma (0.2% vs 0.2%), and B-cell lymphoma (0.3% vs 0.5%) rates were comparable, and no gastrointestinal lymphomas were identified. Hospitalization was more frequent in PSC+UC (45.1% vs 38.2%; RR 1.18; 95% CI 1.12–1.24), while all-cause mortality was similar (10.0% vs 9.5%; RR 1.06; 95% CI 0.93–1.21). CONCLUSION In this large, multi-center cohort, concomitant UC was not associated with a statistically significant increase in overall lymphoma risk among PSC patients, although a trend toward higher non-Hodgkin lymphoma incidence was observed. Longer follow-up is warranted to better define lymphoma risk in this high-risk population.