Lung cancer in systemic lupus erythematosus

Background: Evidence points to a link between systemic lupus erythematosus (SLE) and an increased risk of lung cancer. Our objective was to provide a brief report of the lung cancer cases from an SLE cohort, with respect to demographics, histology, and exposures to smoking and immunosuppressive medications. Methods: Data were obtained from a multi-site international cohort study of over 9500 SLE patients from 23 centres. Cancer cases were ascertained through linkage with regional tumor registries. Results: We analyzed information on histology subtype for 30 lung cancer cases that had occurred across five countries. Most (75%) of these 30 cases were female, with a median age of 61 (range 27-91) years. In eight cases, the histological type was not specified. In the remainder, the most common histological type reported was adenocarcinoma (N = 8; two of the adenocarcinomas were bronchoalveolar carcinoma) followed by small cell carcinoma (N = 6), and squamous cell carcinoma (N = 6) with one case each of large cell carcinoma and carcinoid tumor. Most (71%) of the lung cancer cases were smokers; only the minority (20%) had been previously exposed to immunosuppressive agents. Conclusions: The histological distribution of the lung cancers from the SLE sample appeared similar to that of lung cancer patients in the general population, though the possibility of a higher proportion of more uncommon tumors (such as bronchoalveolar and carcinoid) cannot be excluded. A large proportion of the cancer cases were smokers, which is also not surprising. However, only a minority appeared to have been exposed to immunosuppressive agents. A large case-cohort study currently in progress should help shed light on the relative importance of these exposures in lung cancer risk for SLE patients.