Incidence of and predictive factors for lung cancer in patients with rheumatoid arthritis: A retrospective long-term follow-up study.

Objectives: The aim of this study was to determine the incidence and predictive factors of lung cancer in rheumatoid arthritis (RA).

Methods: We conducted a retrospective follow-up study of patients who were diagnosed with RA at our institution between April 2001 and December 2022. Pulmonary complications were evaluated using high-resolution computed tomography (HRCT) at RA diagnosis. Patients were followed until the diagnosis of lung cancer, diagnosis of other malignancies, death, loss to follow-up, or the end of the study.

Results: Among 771 RA patients, 3.5% were diagnosed with combined pulmonary fibrosis and emphysema (CPFE), 4.9% with interstitial lung disease (ILD) alone, and 6.0% with emphysema alone. During follow-up (mean of 9.3 years), the crude incidence rates of lung cancer per 1000 patient-years were 2.9 in all patients, 47.8 in CPFE patients, 10.5 in ILD patients, 11.9 in emphysema patients, and 0.8 in patients without these complications. Only male patients showed a higher incidence of lung cancer compared with the general population. In multivariable Fine-Gray regression analysis, the presence of HRCT-proven CPFE, ILD, and emphysema, and smoking history were identified as predictive factors for lung cancer in RA patients.

Conclusions: Close monitoring of lung cancer is needed for RA patients with smoking history and pulmonary complications, especially CPFE.