Schairer C, et al. - This work was performed to assess the associations between selected systemic and organ-specific autoimmune diseases and breast cancer risk overall and by tumor estrogen receptor (ER)- and progesterone receptor (PR)- status. Findings revealed reduced breast cancer risk among those with rheumatoid arthritis, systemic lupus erythematosus, and pernicious anemia, and increased risk among those with psoriasis. In this study, researchers noticed statistically significant alterations in risk for rheumatoid arthritis that were limited to ER-positive (+) breast cancer, whereas those for the other 3 conditions were further limited to ER+/PR+ breast cancer. However, differences were statistically significant only for rheumatoid arthritis by ER-status.