Purpose: To evaluate the infection incidence in breast cancer patients whether they have a major autoimmune disease or not. Methods: This retrospective cohort study compared the infection incidence of 174 breast cancer patients with an autoimmune disease, including Sjogren's Syndrome (SS), Rheumatoid Arthritis (RA), and Systemic Lupus Erythematosus (SLE), along with 4429 patients without an autoimmune disease, for the period 2000 to 2016. Six-hundred and ninety six, age-, stage-, and diagnosis era-matched patients without any autoimmune disease were analyzed to eliminate the effects of these confounding factors may have on the results. Results: After adjusting for age, stage and diagnosis era, breast cancer patients with an autoimmune disease had a higher Infection Incidence Ratio (IRR: 2.62) than the patients without any autoimmune disease. In the univariate analysis, patients who had an autoimmune disease (p<0.001), underwent chemotherapy (p<0.001), radiotherapy (p=0.004), and monoclonal antibody therapy (p<0.001) had a higher infection rate. In the multivariate analysis, autoimmune disease was shown to be an independent factor for infection incidence. Conclusion: Autoimmune disease was a potential predictor of infection incidence in breast cancer patients post-treatment after adjusting for clinical confounding factors.
Keywords: autoimmune disease; breast cancer; infection.