A Cochrane review and network meta-analysis concluded that there is need for more research on adverse effects, including cancer, after treatment with tumor necrosis factor a (TNF-a) antagonists and that national registries and large databases would provide relevant sources of data to evaluate these effects.
To investigate whether patients with inflammatory bowel disease (IBD) exposed to TNF-a antagonists were at increased risk of developing cancer.
Nationwide register-based cohort study in Denmark, 1999-2012. Participants were 56,146 patients 15 years or older with IBD identified in the National Patient Registry, of whom 4553 (8.1%) were exposed to TNF-a antagonists. Cancer cases were identified in the Danish Cancer Registry.
Rate ratios (RRs) for incident cancer (overall and site-specific) comparing TNF-a antagonist users and nonusers, estimated using Poisson regression adjusted for age, calendar year, disease duration, propensity scores, and use of other IBD medications.
During 489,433 person-years of follow-up (median, 9.3 years [interquartile range, 4.2-14.0]), 81 of 4553 patients exposed to TNF-a antagonists (1.8%) (median follow-up, 3.7 years [interquartile range, 1.8-6.0]) and 3465 of 51,593 unexposed patients (6.7%) developed cancer, yielding a fully adjusted RR of 1.07 (95% CI, 0.85-1.36). There was no significantly increased risk of cancer in analyses according to time since first TNF-a antagonist exposure (less than 1 year: RR, 1.10 [95% CI, 0.67-1.81]; 1 to less than 2 years: RR, 1.22 [95% CI, 0.77-1.93]; 2 to less than 5 years: RR, 0.82 [95% CI, 0.54-1.24]; 5 or more years: RR, 1.33 [95% CI, 0.88-2.03]) and in analyses according to the number of TNF-a antagonist doses received (1 to 3 doses: RR, 1.02 [95% CI, 0.71-1.47]; 4 to 7 doses: RR, 0.89 [95% CI, 0.55-1.42]; 8 or more doses: RR, 1.29 [95% CI, 0.90-1.85]). No site-specific cancers were in significant excess in fully adjusted models.
In this Danish nationwide study, exposure to TNF-a antagonists among patients with IBD was not associated with an increased risk of cancer over a median follow-up of 3.7 years among those exposed. An increased risk associated with longer-term accumulated doses and follow-up cannot be excluded.