Association of aspirin and other non-steroidal anti-inflammatory drug use with incidence of non-Hodgkin lymphoma.

Non-steroidal anti-inflammatory drugs (NSAIDs), including aspirin, seem to have chemopreventive properties against several types of cancer, particularly colon cancer. Persons with rheumatoid arthritis, an autoimmune disease for which NSAIDs are used commonly, have been reported to be at lower risk of colon cancer but at elevated risk of non-Hodgkin lymphoma (NHL), raising the possibility that NSAIDs may be a risk factor for NHL. We evaluated the association of use of NSAIDs, arthritis history, and risk of NHL in a prospective cohort of 27,290 postmenopausal women from the state of Iowa. The frequency of use of aspirin and of other NSAIDs excluding aspirin (e.g., ibuprofen), as well as a physician diagnosis of rheumatoid arthritis (RA) or osteoarthritis (OA), were self-reported on a questionnaire mailed in 1992. The incidence of NHL was ascertained through annual linkages to the Iowa SEER Cancer Registry. Relative risks (RR) and 95% confidence intervals (CI) were estimated using Cox proportional hazards regression. Through 7 years of follow-up, 131 cases of NHL were identified. Compared to women who did not use either aspirin or other non-aspirin NSAIDs, women using aspirin exclusively (RR = 1.71; 95% CI = 0.94-3.13), non-aspirin NSAIDs exclusively (RR = 2.39; 95% CI = 1.18-4.83), or both types of drugs (RR = 1.97; 95% CI = 1.06-3.68) were at increased risk of NHL. A diagnosis of RA (RR = 1.75; 95% CI = 1.09-2.79), but not OA (RR = 1.06; 95% CI = 0.67-1.68), was associated with risk of NHL, but the positive association of use of aspirin and other NSAIDs with NHL was independent of RA history. Multivariate adjustment for other NHL risk factors only attenuated slightly these associations, whereas exclusion of cases occurring during the first 2 years of follow-up strengthened the associations. These data suggest that use of NSAIDs, either aspirin or other non-aspirin NSAIDs, are associated positively with risk of NHL, and that this association is independent of RA history.