To assess the effects of disease modifying anti-rheumatic drugs (DMARDs) on lung cancer risk in a large rheumatoid arthritis (RA) cohort.
We assembled a cohort of RA patients (N=23,810) from population-based administrative healthcare databases. We ascertained cases of lung cancer in the cohort using physician billing and hospitalization records. Each lung cancer case was age and sex matched to 10 controls. We used conditional logistic regression to determine the effects of DMARDs on lung cancer risk, calculating the adjusted rate ratio (RR) attributable to each DMARD.
Subjects were followed for a total of 157,204 person-years. During this time, 960 cases of lung cancer were recorded. The frequency of exposures to various DMARDs was similar in cases and controls; our adjusted RR estimates, reflecting the independent effects of each DMARD exposure, did not associate any of the drugs with an increased risk of lung cancer.
Our data do not suggest that DMARD exposures are the primary mediator of lung cancer risk in RA. An increased risk of lung cancer in RA patients may be related to other determinants, including shared risk factors for the development of both RA and lung cancer.