Rheumatoid arthritis carries increased lung cancer risk

Rheumatoid arthritis (RA) appears to convey a 50-percent increase in the risk of lung cancer, with the risk increase even more pronounced for individuals with RA-interstitial lung disease (ILD), according to a study.

Researchers used data from the Veterans Health Administration (VA) and identified a cohort of patients with RA and those with RA-ILD based on validated administrative-based algorithms. These patients were then matched to individuals without RA according to age, gender, and VA enrolment year. Lung cancers were identified from a VA oncology database and the National Death Index.

The study cohort consisted of 72,795 patients with RA with 633,937 patients without RA (mean age 63 years, 88 percent male). A total of 17,099 incident lung cancers occurred over 4,481,323 patient-years.

Conditional Cox regression models showed that RA was independently associated with a heightened risk of lung cancer (adjusted hazard ratio [aHR], 1.58, 95 percent confidence interval [CI], 1.52–1.64). This association persisted among participants who had never smoked (aHR, 1.65, 95 percent CI, 1.22–2.24) and among those with incident RA (aHR, 1.54, 95 percent CI, 1.44–1.65).

The increased risk of lung cancer was more pronounced with prevalent RA-ILD (n=757; aHR, 3.25, 95 percent CI, 2.13–4.95) than with RA but not ILD (aHR, 1.57, 95 percent CI, 1.51–1.64). Similar results were observed in an analysis that included both prevalent and incident RA-ILD (RA-ILD vs no-RA: aHR, 2.88, 95 percent CI, 2.45–3.40).

The findings highlight the potential of lung cancer surveillance in RA, and especially RA-ILD, as a useful strategy for reducing the burden posed by lung cancer.