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

Abstract

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. 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. 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). 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.