Less Pathological Axillary Involvement is Observed in Breast Cancer Patients with Autoimmune Thyroid Disease

Background: Autoimmune thyroid disease is more frequently observed in breast cancer patients. There are not enough studies showing the prognostic significance of this association in terms of breast cancer. The aim of this study was to determine the breast cancer molecular subgroup frequency and to examine the relationship between autoimmune thyroid disease and the breast cancer in terms of prognosis and predictive factors. Methods: One hundred and one patients have been included to study. They have been divided into subgroups according to molecular classification. The patients with high serum anti-thyroid peroxidase levels were considered positive for autoimmune thyroid disease. Prognostic and predictive parameters [tumor stage, tumor size, axillary lymph node involvement, histologic grade, lymphovascular , perineural invasion, hormone receptor status, HER2 (Human Epidermal Growth Receptor 2) over expression] were compared between breast cancer patients with autoimmune thyroid disease and those patients without autoimmune thyroid disease. Results: The prevalence of thyroid autoimmunity was 23.8% (n = 24) in breast cancer patients. The axillary lymph node involvement in autoimmune thyroid disease positive breast cancer patients was lower than autoimmune thyroid disease negative patients (37.5% versus 61% respectively, p = 0.043). There were no significant differences between the two groups in terms of other prognostic parameters. More importantly, there was a significantly negative correlation between anti thyroid peroxidase levels and axillary lymph node involvement in patients (r= -0.245, p=0.014). Conclusion: Positive axillary lymph nodes, have been found to be lower in breast cancer patients accompanied by autoimmune thyroid disease. This result supports the view that thyroid autoimmunity is a positive prognostic factor in terms of breast cancer. The mechanism through which it is effective should be examined in new studies. Trial registration: A written approval was granted by the Kirikkale University, Faculty of Medicine, Clinical Research Ethics Committee through the 01/09 Numbered and 19.01.2016 Dated Decision in order to conduct this study. Keywords: Thyroid autoimmune, breast cancer, prognostic factors