NEWS: TNF blockers do not raise cancer risk

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TNF blockers do not raise cancer risk

Last Updated: 2005-09-27 11:51:34 -0400 (Reuters Health)

NEW YORK (Reuters Health) - Although rheumatoid arthritis (RA) is

associated with an increased risk of hematopoietic malignancies,

tumor necrosis factor (TNF) antagonists used in the treatment of RA

do not appear to raise the risk of lymphoma or solid tumors, Swedish

investigators report.

Much of the data regarding cancer risk in RA patients are relatively

old, Dr. Johan Askling, from Karolinska University Hospital in

Stockholm, and colleagues note in two reports, both published in the

October issue of the ls of The Rheumatic Diseases. There has been

evidence that TNF blockers raise the risk of lymphoma, but to assess

the risk of cancer associated with these drugs, contemporary and

comparable data on the expected incidence in RA are required.

Dr. Askling's group therefore assessed cancer risk in three groups of

RA patients: a prevalence cohort of 53,067 subjects diagnosed with RA

between 1990 and 2003, an incidence cohort of 3703 patients (<1 year

from RA onset), and a TNF antagonist cohort of 4160 patients treated

with etanercept, infliximab, or adalimumab between 1999 and 2003.

Through linkage to the Swedish Cancer Register 1964-2003, the authors

observed the standardized incidence ratio (SIR) for lymphoma was 1.9

in the prevalence cohort and 2.0 in the incident cohort. The

corresponding SIRs for leukemia were 2.1 and 2.2, respectively.

When compared with the lymphoma incidence in the prevalence and

incident RA cohorts, the adjusted relative risk of lymphoma in the

TNF antagonist cohort was 1.1. This " marginally augmented lymphoma

risk...must be judged in the light of a higher disease activity among

patients who are offered TNF antagonist treatment, " the authors note.

" The extent to which the increased leukemia risk is caused by the RA

itself, its treatment, or both, remains unknown, " they add.

In the second paper, Dr. Askling's group analyzed the same patient

cohorts for the incidence of solid tumors.

Overall, the SIR for solid cancer was 1.05 in the prevalence cohort

and 1.1 in the incidence cohort. The risk appeared to be greater in

men, largely because of a decreased risk of breast cancer.

The SIR among patients treated with TNF antagonists was 0.9.

The gastrointestinal cancer risk was marginally reduced in the

prevalent cohort (SIR = 0.85), and slightly increased in the TNF-

antagonist cohort (SIR = 1.2).

" Our results suggest that TNF antagonists as actually used in

practice are not associated with a cancer pattern that differs from

that of other patients with RA, " the authors conclude, " although the

non-decreased colorectal cancer occurrence may be a concern. "

Ann Rheum Dis 2005;64:1414-1426.

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