A meta-analysis of the incidence of malignancy in adult patients with rheumatoid arthritis

Allison L Smitten , Teresa A Simon , Marc C Hochberg and Samy Suissa

Arthritis Research & Therapy 2008, 10:R45doi:10.1186/ar2404


Published:	23 April 2008

See related editorial by Solomon and Love, http://arthritis-research.com/content/10/3/109

Abstract (provisional)

Introduction

The risk of malignancies in patients with rheumatoid arthritis (RA) has raised some concern, particularly with immunosuppressive approaches to disease management.

Methods

We conducted a systematic review of the literature and meta-analysis characterizing the associated risk of overall malignancy and four site-specific malignancies (lymphoma, lung, colorectal and breast cancer) in patients with RA. A Medline search from 1990-2007 was conducted using specified search terms and predefined inclusion criteria for identification of relevant observational studies that provide estimates of relative risk of malignancy associated with RA. Study-specific estimates of the relative risk, as measured by standardized incidence ratios (SIRs) and estimated in comparison with the general population, were combined using a random effects model.

Results

A total of 21 publications were identified of which 13 reported the SIR for overall malignancy, 14 for lymphoma, 10 for colorectal, 12 for lung, and 9 for breast cancer. Compared with the general population, the overall SIR estimates suggest that RA patients have approximately a 2-fold increase in lymphoma risk (SIR: 2.08; 95% CI: 1.80-2.39) and greater risk of Hodgkin's than non-Hodgkin's lymphoma. The risk of lung cancer was also increased with a SIR of 1.63 (95% CI: 1.43-1.87). In contrast, a decrease in risk was observed for colorectal (SIR: 0.77; 95% CI: 0.65-0.90) and breast cancers (SIR: 0.84; 95% CI: 0.79-0.90). The SIR for overall malignancy was 1.05 (95% CI: 1.01-1.09).

Conclusions

Patients with RA appear to be at higher risk of lymphoma and lung cancer and potentially decreased risk for colorectal and breast cancer compared with the general population.