Does cancer that occurs during or after anti-tumor necrosis factor therapy have a worse prognosis? A national assessment of overall and site-specific cancer survival in rheumatoid arthritis patients treated with biologic agents

Objective: Tumor necrosis factor (TNF) may affect tumor development and spreading. While data on the incidence of cancer following anti-TNF therapy have been published, the purpose of this study was to examine the clinical presentation and outcome of cancers that develop during or after anti-TNF therapy.

Methods: By linking data from Swedish clinical registries of rheumatoid arthritis (RA) patients, including Anti-Rheumatic Therapy in Sweden (ARTIS), the Swedish Biologics Register, with nationwide data on hospitalizations and outpatient visits for RA, we assembled a cohort of 78,483 RA patients who were alive in 1999 or who entered the cohort thereafter. Of these, 8,562 patients started therapy with a biologic agent (98% started an anti-TNF) during the period from January 1, 1999 to December 31, 2007. Linkage to the Swedish Cancer Register and other registers identified first primary cancers occurring during 1999-2007 as well as post-cancer survival through March 31, 2009. Through this linkage, we identified 314 cancers in patients who were undergoing, or had a history of, treatment with biologic agents and 4,650 cancers in patients who were biologics-naive at the time of cancer diagnosis. The distributions of tumor stage among the biologics-exposed and the biologics-naive patients were compared. The relative risk of death among the biologics-exposed versus the 586 matched biologics-naive cancer cases were assessed by Cox regression analyses. Through chart review in a defined subset, we gathered additional clinical information and validated the diagnoses.

Results: For all cancers combined, the distribution of cancer stages at the time of cancer diagnosis was largely similar between those in the biologics-exposed and the matched biologics-naive groups. Based on the total of 113 deaths among those with cancer in the biologics-exposed group versus the 256 deaths among those with cancer in the biologics-naive group, the relative risk of death following cancer associated with exposure to anti-TNF was 1.1 (95% confidence interval 0.8-1.6).

Conclusion: During routine care, cancers that occur following anti-TNF therapy are not characterized by any markedly altered stage at presentation or by altered post-cancer survival rates.