Thyroid hormone receptor alpha (TRa) tissue expression in ductal invasive breast cancer: A study combining quantitative immunohistochemistry with digital slide image analysis

This is the first-in-human study to combine quantitative immunohistochemistry with image analysis to study TRa expression in women with ductal invasive breast cancer and no clinical or biochemical evidence of thyroid dysfunction. We confirm that TRa is expressed in both normal and malignant breast epithelium and suggest that TRa expression is downregulated during breast carcinogenesis. Larger and higher grade breast cancers demonstrate partial loss in TRa expression. Alterations in TRa expression take place even in the absence of clinical or biochemical thyroid disease. The underlying mechanism of these findings and their potential significance in survival and relapse mandate further research.