Objective: A challenge in the management of breast cancer is development of brain metastases (BM) with limited survival. In primary breast cancer, ER/PR/HER2 are important prognostic markers and are important for making effective treatment decisions. Changes in immunohistochemical markers of metastases are with unclear clinical significance, and mechanisms of resistance to endocrine therapy are an additional challenge. The aim of this retrospective study is to detect changes in immunohistochemical markers of primary and BM and to recognize if receptor change has prognostic impact.
Methods: Twenty-four consecutive primary breast cancer patients who developed BM and got surgical resection of BM were enrolled. Matched pair analyses of primary and BM were done with evaluation by immunostaining (ER/PR/HER2).
Results: A small tumor size, ductal histology and HER2+ tumors were associated with BM. Loss of ER/PR receptor positivity was observed in BM compared to primary (ER: 50.0 %/22.7 %; p = 0.004; PR: 45.8 %/9.1 %; p = n.s), respectively, and almost no change in HER2 status (>80 %; p = 0.012). Patients with ER-/PR-negative or HER2-positive primary had shorter time to recurrence than ER-/PR-positive and HER2-negative patients. Receptor change has negative prognostic impact.
Conclusion: With the observed loss of receptor positivity, therapeutic options are diminished. Identification of patients with a high risk for BM is warranted to evaluate preventive strategies.