According to a study, two years or more of oral steroid treatment decreases the risk of rheumatoid arthritis (RA) related lymphoma.
Furthermore, these effects were found regardless of when in the course of the disease the steroids were first administered. However, these beneficial effects were not observed if the steroids were taken for less than a two-year period.
"The pros and cons of corticosteroid treatment in rheumatoid arthritis have been a subject of much debate and long term steroid treatment is often limited as a result of concerns about various side effects," Study author Dr Eva Baecklund of Uppsala University Hospital, Sweden, said.
"What our data show is a new aspect of steroid treatment. Patients with severe rheumatoid arthritis are at increased risk for malignant lymphomas (cancer in the immune system), but long term steroid treatment may decrease this risk," Baecklund added.
In individuals treated with steroids for over two years, the risk of rheumatoid arthritis-associated lymphomas was significantly reduced (relative risk 0.4; 0.2-0.7), whilst less than two years of steroids yielded no such reduced risk (relative risk 0.9; 0.5-1.5).
The most pronounced protective steroidal effect was observed in the diffuse large B-cell lymphoma subtype - the type of lymphoma most commonly associated with RA 1,2,3 with an odds ratio of 0.7 (0.4-1.0).
The study involved 378 patients with rheumatoid arthritis-associated lymphoma identified from the Swedish Hospital Register and the Cancer Register compared with 378 individually matched RA controls, i.e. patients with RA but without lymphoma.
Using data on steroid treatment type and duration along with inflammatory load collected from cases and controls, information on lymphoma type (where observed) was also collected. The lymphoma tissues were obtained from the pathology laboratories and were reclassified according to the most recent lymphoma classification, the World Health Organization classification.
Interestingly, researchers also compiled information on the duration of RA at initiation of steroid treatment. In this study there was no correlation observed between protective function and length of RA at onset of steroidal treatment.
The protective effect was identical in those starting steroid treatment the first five years after onset of RA and in those starting later (relative risk 0.6; 0.3-0.9). Steroid treatment outcome was not associated with the presence of the Epstein-Barr virus in the lymphomas.
These results build on those of a previously published study that reported that orally prescribed and intra-articular (administered within the joint or joint cavity) steroids protect the individual from the development of malignant (actively cancerous) lymphomas in a dose responsive manner.