Effect of autoimmune diseases on risk and survival in histology-specific lung cancer

Patients with autoimmune diseases are at an increased risk of cancer due to underlying dysregulation of the immune system or treatment. Data on cancer incidence, mortality and survival after autoimmune diseases would provide further information on the clinical implications. We systematically analysed data on lung cancer in patients diagnosed with 33 different autoimmune diseases. Standardised incidence ratios (SIRs), standardised mortality ratios (SMRs) and hazard ratios (HRs) were calculated for subsequent incident lung cancers or lung cancer deaths up to 2008 in patients hospitalised for autoimmune disease after 1964. Increased risks of lung cancer were recorded for SIRs after 12 autoimmune diseases, SMRs after 11 autoimmune diseases and HRs after two autoimmune diseases. The highest SIRs and SMRs, respectively, were seen after discoid lupus erythematosus (4.71 and 4.80), polymyosistis/dermatomyositis (4.20 and 4.17), systemic lupus erythematosus (2.47 and 2.69), rheumatic fever (2.07 and 2.07) and systemic sclerosis (2.19 and 1.98). Autoimmune disease did not influence survival overall but some autoimmune diseases appeared to impair survival in small cell carcinoma. All autoimmune diseases that had an SIR >2.0 are known to present with lung manifestations, suggesting that the autoimmune process contributes to lung cancer susceptibility. The data on survival are reassuring that autoimmune diseases do not influence prognosis in lung cancer.