Isolated pachymeningeal metastasis from breast cancer: Clinical features and prognostic factors.

Purpose: To evaluate the clinical features and prognoses of patients with isolated pachymeningeal metastasis (IPM) from breast cancer.

Methods: We reviewed the medical records of all patients with metastatic breast cancer (MBC) treated from January 2009 to August 2016. Eligibility criteria included diagnosis of pachymeningeal metastasis based on brain magnetic resonance imaging and histologic diagnosis of primary breast cancer. We excluded patients with concomitant parenchymal or leptomeningeal metastases.

Results: Thirty-eight patients who matched our inclusion criteria were included in this study. The incidence of IPM in breast cancer was 1.5% of all patients with MBC. The molecular subtype distribution was: triple negative, 29.0%; ER+/HER2-, 44.7%; ER+/HER2+, 18.4%; and ER-/HER2+, 7.9%. All isolated pachymeningeal involvement resulted from the direct extension of skull metastases. The median time to IPM from systemic metastasis was 28.6 (95% CI: 23.6-33.6) months. The median time to IPM from skull metastasis was 5.2 (95% CI: 0-10.9) months. The median overall survival (OS) from IPM was 4.0 (95% CI: 2.5-5.5) months. In patients who received chemotherapy the OS was longer than for those who received radiotherapy or supportive care only [median OS 8.9 (95% CI: 0.0-18.4), 2.8 (95% CI: 0.5-5.0), and 0.8 (95% CI: 0.6-1.1) months, respectively (p = 0.006)]. Multivariate analysis revealed that good performance status and chemotherapy were associated with better survival outcomes.

Conclusion: Stratified evaluation is required for patients with skull metastasis from breast cancer, as pachymeningeal involvement can develop and be associated with unsuspected outcomes.