Abstract
OBJECTIVE: Metastatic breast cancer (MBC) remains a major cause of cancer-related mortality, with limited treatment options in advanced stages. Eribulin is now recommended for MBC and covered by the Indonesian National Health Insurance Policy as monotherapy for 6 cycles. However, data on its effectiveness and safety in Indonesian patients remain scarce. This study aimed to evaluate the disease control rate, overall survival (OS), and adverse events of eribulin monotherapy after 6 treatment cycles in Indonesian MBC patients. METHODS: This multi-center bidirectional longitudinal study was conducted in Indonesia (November 2023 - December 2024). Patients with stage IV MBC receiving eribulin were included. Demographic data, tumor response, OS, and adverse events were extracted from medical records. Kaplan-Meier analysis and the log-rank test were used to assess OS, while Cox regression evaluated potential prognostic factors. Adverse events were analyzed using descriptive statistics. RESULT: A total of 53 patients were included, with 54.7% aged >50 years and 56.6% classified as luminal subtype. The majority (51.0%) received eribulin as a third-line or later treatment, and 56.6% had lung metastases. Disease control was achieved in 43.4% of patients after 6 cycles. The median OS was 10 months (95% CI: 6.81 - 13.18 months). Eribulin was well tolerated, with nausea (32.1%) being the most common adverse event. CONCLUSION: This study suggests that eribulin monotherapy is associated with disease control and survival benefits in Indonesian MBC patients while maintaining a manageable safety profile. However, further prospective studies are needed to confirm its long-term efficacy, impact beyond 6 cycles, and comparative effectiveness relative to other chemotherapy regimens.