Increased expression of thyroid hormone receptor alpha and estrogen receptor alpha in breast cancer associated with thyroid cancer

Introduction: Breast cancer co-occurred with thyroid cancer might be associated with thyroid hormone receptor (TR) and estrogen receptor (ER), but few have been reported. We aimed to investigate the expression and prognostic significance of ERs and TRs in such settings. Material and methods: Tissue microarrays were constructed from 75 patients with breast and thyroid cancer (BC + TC) who were retrospectively recruited between 1999 and 2012 and 147 with breast cancer only (BC controls). The ER alpha, ER beta, TR alpha, and TR beta expression levels were analyzed by immunohistochemistry. Results: TR alpha expression was more frequently observed in the BC + TC group than the BC control group both in the normal (51.5% vs 23.3%, respectively, p = 0.009) and cancer tissues (21.6% vs 6.8%, respectively, p = 0.001). The BC + TC group showed greater ER alpha-positivity in the cancer tissues (79.7% vs 58.7%, respectively, p = 0.002) than the BC control group. The degree of ER alpha-and TR alpha-positivity was unchanged by radioactive treatment or serum thyroid stimulating hormone levels. In the BC + TC group, ER alpha-positivity was associated with earlier disease stage I/IIA (81.0% vs 50.0%; p = 0.031) and lower recurrence rates (8.5% vs 40.0%; p = 0.002). TR alpha-positivity alone was not associated with any recurrence-free survival-related differences, and ER alpha-and TR alpha-negativity were associated with significantly shorter recurrence-free survival (p < 0.001). Conclusion: Enhanced ER alpha and TR alpha expression in breast cancer is associated with thyroid cancer occurrence, and the observed association with prognosis suggests the possible role of ERs and TRs in the link between breast cancer and thyroid cancer. (C) 2021 Elsevier Ltd, BASO -The Association for Cancer Surgery, and the European Society of Surgical Oncology. All rights reserved.