Background: Central nervous system (CNS) relapse is increasing in breast cancer. This increase may reflect altered failure patterns from adjuvant therapy, more effective systemic therapy with improved control in non-CNS sites, or a resistant breast cancer subtype.
Methods: To determine the factors associated with clinical CNS relapse, we examined response to neoadjuvant chemotherapy (chemosensitivity), time to relapse and sites of relapse in a cohort of 140 patients without evidence of metastasis at presentation.
Results: At 5 years (interquartile range 3-6 years), 44 (31%) patients developed distant metastases, including 13 with CNS metastases. CNS relapse was early (median 24 months after diagnosis) and associated with relapse in bone and liver, suggesting hematogenous dissemination. Those with CNS relapse were younger at diagnosis (40 versus 49 years) and more likely to have lymphovascular invasion in the primary tumor compared with non-CNS metastases. Response to neoadjuvant chemotherapy was not different (69% versus 73% response rate) between the two groups. Extent of residual disease after chemotherapy was strongly associated with relapse outside the CNS but not CNS relapses. The CNS was an isolated or dominant site of metastasis in 8 of 13. Despite treatment, most patients with CNS involvement died of neurologic causes a median of 6 months later.
Conclusion: Breast cancers that develop CNS metastases differ from those that develop metastases elsewhere. Both tumor behavior and reduced chemotherapy accessibility to the CNS may contribute to increased CNS involvement in breast cancer patients treated with multimodality therapy.