RESEARCH - Anti-TNF therapy in RA and risk of malignant lymphomas: relative risks and time trends in the Swedish Biologics Register

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Ann Rheum Dis. 2009 May;68(5):648-53. Epub 2008 May 8.

Anti-tumour necrosis factor therapy in rheumatoid arthritis and risk

of malignant lymphomas: relative risks and time trends in the Swedish

Biologics Register.

Askling J, Baecklund E, Granath F, Geborek P, Fored M, Backlin C,

Bertilsson L, Cöster L, sson LT, Lindblad S, Lysholm J,

Rantapää-Dahlqvist S, Saxne T, van Vollenhoven R, Klareskog L,

Feltelius N.

Department of Medicine, Clinical Epidemiology Unit, Karolinska

Institutet at Karolinska University Hospital, Stockholm, Sweden.

BACKGROUND: Tumour necrosis factor (TNF) antagonists have proved

effective as treatment against rheumatoid arthritis (RA), but the

unresolved issue of whether the use of anti-TNF therapy increases the

already elevated risk of lymphoma in RA remains a concern.

METHODS: Using the Swedish Biologics Register (ARTIS), the Swedish

Cancer Register, pre-existing RA cohorts and cross-linkage with other

national health and census registers, a national RA cohort (n =

67,743) was assembled and patients who started anti-TNF therapy

between 1998 and July 2006 (n = 6604) were identified. A general

population comparator (n = 471,024) was also assembled and the

incidence of lymphomas from 1999 to 31 December 2006 was assessed and

compared in these individuals.

RESULTS: Among the 6604 anti-TNF-treated RA patients, 26 malignant

lymphomas were observed during 26,981 person-years of follow-up, which

corresponded to a relative risk (RR) of 1.35 (95% CI 0.82 to 2.11)

versus anti-TNF-naive RA patients (336 lymphomas during 365,026

person-years) and 2.72 (95% CI 1.82 to 4.08) versus the general

population comparator (1568 lymphomas during 3,355,849 person-years).

RA patients starting anti-TNF therapy in 1998-2001 accounted for the

entire increase in lymphoma risk versus the two comparators. By

contrast, RR did not vary significantly by time since start of first

treatment or with the accumulated duration of treatment, nor with the

type of anti-TNF agent.

CONCLUSION: Overall and as used in routine care against RA, TNF

antagonists are not associated with any major further increase in the

already elevated lymphoma occurrence in RA. Changes in the selection

of patients for treatment may influence the observed risk.

PMID: 18467516

http://www.ncbi.nlm.nih.gov/pubmed/18467516

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