How are cancer and connective tissue diseases related to sarcoidosis?

Several studies have suggested an association between sarcoidosis and cancer, and between sarcoidosis and connective tissue diseases (CTDs). In this review, we discuss the evidence supporting and refuting these associations.

In terms of a cancer risk in sarcoidosis patients, the data are somewhat conflicting but generally show a very small increased risk. The data supporting an association between sarcoidosis and CTD are not as robust as for cancer. However, it appears that scleroderma is the CTD most strongly associated with sarcoidosis.

There are several important clinical and research-related implications of the association of sarcoidosis and CTDs. First, rigorous efforts should be made to exclude alternative causes for granulomatous inflammation before establishing a diagnosis of sarcoidosis. Second, the association between sarcoidosis and both cancer and CTDs may yield important insights into the immunopathogenesis of all three diseases. Finally, these data provide insight in answering a common question asked by sarcoidosis patients, 'Am I at an increased risk of developing cancer?' We believe that although there is an increased (relative) risk of cancer in sarcoidosis patients compared with the general population, that increased risk is quite small (low absolute risk).