Lung cancer in rheumatoid arthritis. Is there a need for better risk assessment and screening?

Extra-articular manifestations are common in rheumatoid arthritis (RA), with lung involvement being one of the commonest. Apart from interstitial lung disease which is a well-recognized manifestation, it seems that lung cancer has also increased frequency in RA. In fact, recent meta-analyses have suggested that in RA compared with the general population, lymphomas and lung malignancy are more frequent. For the latter, male gender, seropositivity for rheumatoid factor and/or anti-citrullinated protein antibody (ACPA), as well as older age, has been suggested, among others, as risk factors. Several hypotheses have been formulated to explain the increased frequency of lung cancer in RA. These include smoking and/or interstitial lung as common risk factors for both RA and lung cancer and chronic inflammation predisposing to malignant diseases. Numerous questions remain to be answered. For example, are there any risk factors (e.g., positivity for rheumatoid factor or anti-citrullinated peptide antibodies) that would predict the development of lung cancer in these patients? Are there any screening procedures appropriate for early diagnosis and therefore better outcome? Data from large registries are needed to better define the profile of these patients.