Comparison of Receptor Profiles Between Primary Tumors and Isolated Thoracic Metastases in Breast Cancer

Background: Receptor status may change during metastatic progression, potentially altering therapeutic decisions and outcomes. The aim of this study was to determine ER, PR, and HER2 changes in thoracic metastases [pleura, lung, lymph node, pericardium, chest wall] of breast cancer and to evaluate their impact on survival. Methods: Data of 46 women who underwent interventional procedure for thoracic metastasis of breast cancer and had available ER/PR/HER2 assessment in both primary and corresponding metastatic tissues were retrospectively analyzed. Post-metastasis survival was calculated from the date of histopathological confirmation of metastatic disease. The associations of primary breast cancer receptor status, metastatic receptor status, and receptor conversion at metastasis with survival outcomes were investigated. Results: The pleura was the most common metastatic site [54,3%]. In primary tumors, ER, PR, and HER2 positivity rates were 87%, 63%, and 21%, respectively, whereas in metastatic tissues they were 69.6%, 45.7%, and 25.6%. ER loss was observed in 17.4% of cases, with no gain detected. PR loss occurred in 23.9% and gain in 6.5%, while HER2 loss and gain were observed in 7.0% and 11.6% of cases, respectively. Univariate analysis identified pleural metastasis [HR = 3,442, p = 0,017], ER negativity in metastatic tissue [HR = 3,306, p = 0,008], PR negativity in metastatic tissue [HR = 2,793, p = 0,037], and ER loss [HR = 3,095, p = 0,022] as adverse prognostic factors. In multivariate analysis, pleural metastasis [HR = 4,424, p = 0,009] and ER loss [HR = 3,669, p = 0,010] remained independent predictors of poor survival. No significant association was found between HER2 status and survival. Conclusion: ER loss and pleural metastasis are independent adverse prognostic factors in thoracic metastases of breast cancer. Re-evaluation of receptor status in metastatic disease is crucial for optimal treatment selection and prognostic assessment.