Lung cancer in systemic lupus erythematosus

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.

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.

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.

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.