Impact of autoimmune diseases on outcome of patients with early breast cancer

Our aim was to analyze the impact of a concurrent autoimmune disease on outcome of patients with early breast cancer. We reviewed medical charts of patients with a diagnosis of autoimmune diseases (AD) among a population of 17.153 cases. We categorized ADs as endocrine, rheumatic, systemic, neurological diseases and vasculitis. For each patient in the study group, we matched 2 patients. The events to determine overall survival (OS) and disease free survival (DFS) were identified from follow-up data. We identified 279 (1.62%) patients with early breast cancer and concurrent ADs. The median follow-up was 7.0 years. The 10-year OS rate was 86% (95% CI, 80% to 91%) in the study group and 90% (95% CI, 86% to 93%) for the control group (p = 0.011). In patients with ER positive/HER2 negative subtype a worse OS was observed in the study group when compared to the control group (p = 0.0046); this difference remained statistically significant when the analysis was restricted to breast cancer mortality (p = 0.045). The 10-year DFS rate was 69% (95% CI, 61% to 76%) in the study group and 72% (95% CI, 66% to 77%) for the control group (p = 0.22). Autoimmunity at diagnosis of early breast cancer is associated with worse survival.