Background and objective: The brain is one of the most common metastatic sites of breast cancer. Brain metastases develop in 10%-15% of patients with breast cancer and are associated with poor prognosis. The purpose of this retrospective study was to analyze the clinical characteristics and survival of patients with brain metastases due to breast cancer of different subtypes and to identify the prognostic factors that affect clinical outcome.
Methods: A total of 89 patients with breast cancer brain metastases diagnosed between October 1997 and July 2008 at Sun Yat-sen University Cancer Center were included in this study. Among the 89 patients, the number of luminal A, luminal B, human epidermal growth factor receptor 2 (HER-2), and triple-negative (TN) subtypes were 30, 20, 16, and 14, respectively; 9 patients had an unknown subtype. The clinical characteristics, pathologic features, and prognostic factors were analyzed both at the initial diagnosis and at the diagnosis of brain metastases. Endocrine therapy for patients with luminal subtypes was further studied.
Results: The median age of patients was 46 years (range 28-74 years). The median survival time was 8.0 months (range, 0-80 months), the 1-year survival rate was 32% and the 5-year survival rate was 4%. The time to brain metastasis differed according to clinical stage at the initial diagnosis, and the time for patients with the luminal A subtype was the longest (P < 0.001). Multivariate analysis demonstrated that performance status score > 1, multiple brain metastases and without whole brain radiotherapy (WBRT) in combination with chemotherapy were associated with poor prognosis. Compared with the luminal A subtype, features of the HER-2 and TN subtypes included early metastases, rapid progression after first-line treatment (8.0 months vs. 11.0 months), and poor overall survival (25.0 months vs. 63.0 months). The luminal A subtype showed a tendency for good prognosis and slow growth. Tamoxifen could improve the survival of luminal A/B subtypes (median survival 24.0 months vs. 7.0 months, respectively, P = 0.002).
Conclusions: The prognosis of brain metastases from breast cancer was poor, especially in patients with HER-2 and TN subtypes. Generally, WBRT in combination with chemotherapy was the standard treatment modality. Patients with the luminal subtypes could benefit from tamoxifen.