Purpose: Central nervous system (CNS) metastases are a significant burden in breast cancer (BC). Capecitabine is a frequent choice in this scenario, but data supporting its single-agent activity are scarce. We aimed to evaluate the intracranial efficacy of capecitabine in CNS metastases from BC.

Methods: This retrospective cohort included patients with CNS metastases from BC treated with capecitabine at a single centre. Study endpoints were intracranial CNS objective response rate (CNS-ORR), intracranial CNS disease control rate (CNS-DCR), intracranial CNS progression-free survival (CNS-PFS) and overall survival (OS).

Results: 209 patients were included; 41.6% hormone receptor-positive HER2-negative (HR + HER2-), 33.9% human epidermal growth factor receptor 2 positive (HER2+), and 26.4% triple-negative breast cancer (TNBC). Radiotherapy was performed in 90.4% and CNS surgery in 27.5%. Among patients accessible for intracranial response, 3-month CNS-ORR and CNS-DCR were 41.6% and 81.2%. CNS-ORR was numerically higher among TNBC (61% versus 38% in HR + HER2-BC and 35% in HER2 + BC) (p = 0.194). When considering patients who were not evaluable at 3-month as non-responders, the 3-month CNS-ORR was 19.1% (18.4% in HR + HER2-, 18.3% in HER2+, and 21.6% in TNBC). Nevertheless, TNBC was associated with lower CNS-PFS (p < 0.001) and OS (p < 0.001). Median PFS was 8.3 months in HR + HER2-, 5.0 months in HER2+, and 3.0 months in TNBC. Median OS was 8.7, 9.1 and 4.5 months, respectively.

Conclusion: Among patients with BC and CNS metastases accessible for intracranial response at 3 months, intracranial activity was observed with capecitabine. These patients have a poor prognosis regardless of the BC subtype, especially in scenarios where newer therapeutic options are unavailable