RESEARCH - Severe RA linked to lymphoma risk

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Severe Rheumatoid Arthritis Linked to Lymphoma Risk

By Jeff Minerd,

Published: February 27, 2006

Reviewed by Jasmer, MD; Assistant Professor of Medicine,

University of California, San Francisco Earn CME/CE credit

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UPPSALA, Sweden, Feb. 27 - Severe and longstanding rheumatoid

arthritis leads to 70 times the risk for developing lymphoma compared

with patients having mild disease, according to researchers here.

Action Points

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The good news is that standard disease-modifying, anti-rheumatic drug

(DMARD) treatment was not associated with increased lymphoma risk, the

researchers said.

Drawing from a national register of nearly 75,000 Swedish RA patients,

the study focused on 378 of them who were diagnosed with malignant

lymphoma between 1964 and 1995. Using 378 individually matched RA

patients who were free of lymphoma, the researchers calculated odds

ratios for lymphoma associated with low, medium, and high RA disease

activity.

Compared with patients with low disease activity, those with medium

disease activity had a more than sevenfold increase in lymphoma risk

(odds ratio=7.7; 95% confidence interval=4.8-12.3), and those with

high disease activity had a 71-fold risk increase (OR=71.3; 95%

CI=24.1-211.4).

Fifty-two percent of RA patients with lymphoma were categorized with

medium disease, and 23% of RA patients were classified as having high

disease activity, based on duration of symptoms and swollen and tender

joint counts.

The researchers also looked for an association between lymphoma risk

and RA treatment, including methotrexate, anti-malarial agents, oral

steroids, non-steroidal anti-inflammatory drugs, and aspirin. But no

link association was found.

Only the drug azathioprine (Imuran, Azasan) was associated with

significantly increased lymphoma risk (OR=4.3; 95% CI=1.6-12.0), but

this drug is not regarded as a traditional DMARD and is rarely used in

current RA treatment, the investigators said.

The chronic inflammation and stimulation of the immune system in RA

likely leads to cancer through as-yet unspecified pathways, the

researchers speculated.

" The association between lymphoma risk and very high and/or

longstanding disease activity indicates that most patients with RA

will never have any clinically relevant increased lymphoma risk, " the

authors said. " In contrast, those who do may have highly increased

risks, but can be readily identified based on their accrued

inflammatory burden. "

They added, " Conventional medical treatment to suppress and alleviate

disease activity is not by itself a risk factor for lymphoma. Rather,

it is possible that aggressive treatment may reduce lymphoma risk by

reducing cumulative inflammation. "

Primary source: Arthritis & Rheumatism

Source reference:

Baecklund E et al. Association of chronic inflammation, not its

treatment, with increased lymphoma risk in rheumatoid arthritis.

Arthritis & Rheumatism. 2006; 54(3):692-701.

http://www.medpagetoday.com/Rheumatology/Arthritis/tb/2749

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