Mortality from cancer in patients with rheumatoid arthritis.

Data in nationwide Finnish registers were used to study the relationship between rheumatoid arthritis (RA) and site-specific cancers as a cause of death. The study included in all 1,666 subjects who had died in 1989 and who were entitled, under the nationwide sickness insurance scheme, to specially reimbursed medication because of RA. There were 277 deaths from malignancies. The proportion of such deaths in relation to all deaths declined with the duration of RA (p < 0.05). There was an excess of hematopoietic malignancies, particularly in males (p < 0.05). Deaths due to these malignancies, in relation to all cancer deaths, accumulated in long-lasting RA (p < 0.05). This suggests that hematopoietic malignancies arise as a complication of either RA or its treatment and to some degree argues against the notion of a shared etiological agent for these diseases.