Purpose: Approximately 40% of HER2-positive breast cancer patients will develop brain metastases, usually during the first 2-3 years following initial diagnosis and up to 2 years after overt metastatic spread. However, there are no data about brain metastases development as a late disease relapse. In addition, there are no data whether the high incidence of brain metastases is maintained in patients with HER2 overexpression even in late brain metastases. The aim of this paper was to determine the incidence of brain metastases and the HER2 status in patients who developed late relapse, at least 5 years after the initial diagnosis.
Patients and methods: Among 384 consecutive breast cancer patients with late relapse, only 8 developed brain metastases. Archival pathological specimens of the primary tumors of those 8 patients were tested by immunohistochemistry (IHC) for HER2 status.
Results: The incidence of late brain metastases was 2% (8/384). None of these patients had HER2 3+ primary breast cancer.
Conclusion: This study shows that the risk for brain metastases in HER2 3+ breast cancer patients is very low or might be even absent as a late relapse. Absence of late brain metastases in HER2 3+ breast cancer might be attributed to specific biological characteristics of HER2 3+ carcinomas to develop brain metastases mostly in the early course of metastatic disease.