Clinicopathological features of lung cancer in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is a connective tissue disorder (CTD) associated with an increased risk of malignancy including lung cancer (LC).

Clinicopathologic characteristics of LC patients with RA and without systemic CTD were compared to identify the potential differences. A further intra-group comparison was conducted in LC patients with RA according to smoking status to explore the effect of smoking on the clinicopathologic characteristics of LC patients with RA.

A total of 44 LC patients with RA and 176 LC patients without systemic CTD were included in this study. There were no statistically significant differences in the distribution of age, gender, smoking status, histology type, and tumor location between the two groups. However, a significantly larger proportion of patients with stage IV LC was noted in LC with RA group (59.1% vs. 39.2%, P=0.017). Besides, more LC patients with RA had an Eastern Cooperative Oncology Group (ECOG) performance score (PS) ≥2 (8.0% vs. 20.5%, P=0.015). On multivariate analysis, tumor stage (OR: 1.41, 95% CI: 1.23-13.70, P=0.021) and presence of RA (OR: 1.35, 95% CI: 1.34-11.16, P=0.012) demonstrated independent associations with poorer ECOG PS. RA-interstitial lung disease (RA-ILD) was observed in 18 LC patients (40.9%) with RA. Among them, usual interstitial pneumonia (UIP) was observed only in past or current smokers, whereas non-specific interstitial pneumonia (NSIP) was observed only in non-smokers.

There were no statistically significant differences in the distribution of age, gender, smoking status, histology type, and tumor location between LC patients with RA and those without systemic CTD. Compared with LC patients without CTD, LC patients with RA were more likely to be diagnosed at an advanced stage and have a poorer ECOG PS score, and were less likely to receive surgery, radiotherapy, chemotherapy and targeted therapy.