SEATTLE — High systemic inflammatory activity is suspected to be a major risk determinant of lymphomagenesis, and past epidemiological studies have consistently demonstrated a link between rheumatoid arthritis and the incidence of lymphoma.
A study in RMD Open – Rheumatic & Musculoskeletal Diseases suggested that, with advances in therapeutic options for RA management in recent years, the resulting lower level of disease activity could have led to a decline in lymphoma incidence in patients with RA.1
To determine that, a study team led by researchers from the University of Washington and the Iowa City, IA, VA Health Care System examined recent trends in lymphoma incidence in U.S. veterans with RA.
For the study, RA patients were identified in the VA Corporate Data Warehouse. Researchers focused on lymphoma incidence through the end of 2018 from the VA Central Cancer Registry and compared that among patients diagnosed during 2003-2005, 2006-2008, 2009-2011 and 2012-2014.
Results indicated that, among persons diagnosed with RA during 2003-2005, the incidence of lymphoma in the next six years was 2.0 per 1000 person-years. “There was a steady decline in lymphoma incidence during the corresponding 6 years following diagnosis in the subsequent three cohorts, with a rate of 1.5 per 1000 person-years in the 2012-2014 cohort (incidence relative to that in the 2003-2005 cohort=0.79 (95% CI 0.58 to 1.1)),” the authors wrote. “There was no similar decline in lymphoma incidence in VA patients diagnosed with osteoarthritis.”
Researchers said they “observed a decline in lymphoma incidence in recent years among American veterans with RA,” but said further studies are needed to evaluate the specific factors driving the trend.
The study team posited that the declining lymphoma incidence in RA might be related to better disease control by early and intensive treatments in recent years. The authors noted that past studies evaluated trends in the use of DMARDs in RA patients being treated at the VA and determined that use of methotrexate as the first DMARD increased from 39.9% in 1999–2001 to 57.2% in 2008–2009.
Earlier research also indicated that RA patients diagnosed in 2008–2009 had a 74% higher chance of an earlier start on biologics than those diagnosed in 1999–2001 and that the time interval between RA diagnosis and treatment with DMARDs and biological agents decreased from a median of 51 days in 1999–2001 to 28 days in 2006–2007.
More recently, studies have shown that the percentage of veterans with RA receiving DMARD treatment – biologic or non-biologic — increased between 2007 and 2015 (50.4% (95% CI 47.5 to 53.2) to 68.6% (95% CI 65.6 to 71.4)).
“Also, the possible contribution of direct lymphoma suppression—as opposed to indirect suppression via reduced inflammatory biology—with use of anti-CD20 monoclonal antibody such as rituximab could be another possible explanation that requires further exploration,” the authors wrote.
- Singh N, Gao Y, Field E, et al. Trends of lymphoma incidence in US veterans with rheumatoid arthritis, 2002-2017. RMD Open. 2020;6(2):e001241. doi:10.1136/rmdopen-2020-001241