Risk of Primary Gastrointestinal Lymphoma in Patients With Inflammatory Conditions Exposed to Tumor Necrosis Factor Alpha Inhibitors and Immunomodulators: A Case-Control Study.

INTRODUCTION: The aim of this case-control study was to determine if exposure to tumor necrosis factor alpha inhibitors (TNFIs) or immunomodulators (thiopurines or methotrexate) was associated with development of primary gastrointestinal lymphoma (PGIL) in patients with chronic inflammatory conditions.

METHODS: Patients with PGIL and controls evaluated at a tertiary care center over 20 years were matched 1:3 using a medical record informatics search engine based on their chronic inflammatory condition (Crohn's disease [CD], ulcerative colitis [UC], rheumatoid arthritis, ankylosing spondylitis, and psoriatic arthritis) and duration of follow-up. Patients who started on TNFI within 3 months of PGIL diagnosis were excluded. We extracted demographics, medical history, and medications used. Univariate models using conditional logistic regression were used due to the small number of matched pairs.

RESULTS: Twenty PGIL cases matched with 60 controls were followed for a mean 9.9 ± 6.9 and 9.7 ± 8.6 years, respectively. Mean age at time of PGIL diagnosis was 47.5 ± 22.0 (standard deviation) years and the majority (75%) were males. The most common inflammatory diagnosis was inflammatory bowel disease (80% of cases; 45% with UC and 35% with CD). Development of PGIL was not associated with TNFI (odds ratio [OR] = 2.6; 95% confidence interval [CI] 0.69-11.01; P  = .18), but with use of TNFI in combination with thiopurines (OR = 8.93; 95% CI 1.43-80.25; P  = .014). Risk of PGIL increased with every additional TNFI (2.277 (1.002-5.713); P  = .0494). All cases exposed to multiple TNFI were also exposed to thiopurines. Use of thiopurines (alone or in combination) was the greatest risk factor (OR = 6.32; 95% CI 1.55-37.05; P  = 0.006) to develop PGIL.

CONCLUSIONS: TNFI therapy was not associated with increased risk for PGIL unless used in combination with thiopurines and with every switch to a different TNFI.