Brooks et al. evaluated the risk of lung cancer in patients with rheumatoid arthritis (RA) and RA-associated interstitial lung disease (ILD) compared with the risk in matched controls without RA or RA-ILD. The underlying reasons for an increased risk of lung cancer in patients with RA are not well understood. Prior studies have often failed to adjust for cigarette smoking, a shared risk factor for RA and lung cancer. Understanding whether RA predisposes someone to the development of lung cancer independent of other risk factors and whether patients with RA-ILD represent a uniquely high-risk group could inform cancer-screening strategies.
Methods
The researchers performed a retrospective, matched cohort study of patients with RA and RA-ILD within the Veterans Health Administration between 2000 and 2019. Patients with RA and RA-ILD were identified with algorithms, then matched to individuals without RA who shared the same age, gender and Veterans Health Administration enrollment year. Lung cancer occurrences were identified using a Veterans Health Administration oncology database and the National Death Index. Conditional Cox regression models assessed lung cancer risk adjusting for race, ethnicity, smoking status, Agent Orange exposure and comorbidity burden among matched individuals. Several sensitivity analyses were performed.
Results
The researchers matched 72,795 patients with RA with 633,937 patients without RA (mean age 63 years; 88% male). Over 4,481,323 patient-years, 17,099 incident lung cancers occurred. RA was independently associated with an increased risk of lung cancer, which persisted in those who had never smoked. Compared with non-RA controls, RA-ILD was more strongly associated with lung cancer risk than RA without ILD.
Conclusions
In summary, both RA and RA-ILD were associated with an increased risk of lung cancer independent of other risk factors for lung cancer. Smoking status, a shared risk factor for RA/RA-ILD and lung cancer, did not fully explain the heightened risk of lung cancer observed in RA/RA-ILD.
Increased lung cancer surveillance in patients with RA, and especially those with RA-ILD, may be a useful strategy to reduce the burden posed by this leading cause of cancer death.
For complete details, including source material, refer to the full study.
Excerpted & Adapted From
Brooks RT, Luedders B, Wheeler A, et al. The risk of lung cancer in rheumatoid arthritis and rheumatoid arthritis–associated interstitial lung disease. Arthritis Rheumatol. 2024 Dec;76(12).
