RESEARCH - Biologic treatment of RA and the risk of malignancy: analyses from a large US observational study

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Volume 56, Issue 9, Pages 2886-2895

Published Online: 29 Aug 2007

Biologic treatment of rheumatoid arthritis and the risk of malignancy:

Analyses from a large US observational study

Frederick Wolfe 1 *, Kaleb Michaud 2

1National Data Bank for Rheumatic Diseases and University of Kansas

School of Medicine, Wichita

2University of Nebraska Medical Center, Omaha

Abstract

Objective

Induction of malignancy is a major concern when rheumatoid arthritis

(RA) is treated with biologic therapy. A meta-analysis of RA biologic

clinical trials found a general increased risk of malignancy, but this

risk was not found in a large observational study. We undertook this

study to assess the risk of malignancy among biologic-treated patients

in a large US observational database.

Methods

We studied incident cases of cancer among 13,001 patients during

49,000 patient-years of observation in the years 1998-2005. Cancer

rates were compared with population rates using the US National Cancer

Institute SEER (Surveillance, Epidemiology, and End-Results) database.

Assessment of the risk of biologic therapy utilized conditional

logistic regression to calculate odds ratios (ORs) as estimates of the

relative risk, further adjusted for 6 confounders: age, sex, education

level, smoking history, RA severity, and prednisone use.

Results

Biologic exposure was 49%. There were 623 incident cases of

nonmelanotic skin cancer and 537 other cancers. The standardized

incidence ratios and 95% confidence intervals (95% CIs) compared with

SEER data were as follows: all cancers 1.0 (1.0-1.1), breast 0.8

(0.6-0.9), colon 0.5 (0.4-0.6), lung 1.2 (1.0-1.4), lymphoma 1.7

(1.3-2.2). Biologics were associated with an increased risk of

nonmelanotic skin cancer (OR 1.5, 95% CI 1.2-1.8) and melanoma (OR

2.3, 95% CI 0.9-5.4). No other malignancy was associated with biologic

use; the OR (overall risk) of any cancer was 1.0 (95% CI 0.8-1.2).

Conclusion

Biologic therapy is associated with increased risk for skin cancers,

but not for solid tumors or lymphoproliferative malignancies. These

associations were consistent across different biologic therapies.

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