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Abstract Purpose: Leptomeningeal metastasis (LM) is well-known for its dismal prognosis. Despite various treatment approaches, there has been minimal improvement in survival, and the optimal treatment for leptomeningeal metastasis remains uncertain. Our study aimed to report treatment outcomes using different modalities for LM and to identify prognostic factors. Materials and Methods: We analyzed 111 breast cancer patients with LM, who were treated at Seoul National University and Seoul Metropolitan Government Seoul National University Boramae Medical Center between January 2010 and December 2022. The median follow-up period was 4. 4 months (range, 0. 2 – 125. 4 months). Results: The median age was 48 years, with the majority having a Karnofsky performance status below 60 (n = 100, 90. 1%). Among the 111 patients, intrathecal chemotherapy was the most commonly used treatment modality (n = 89, 80. 2%), followed by radiotherapy (n = 74, 66. 7%), and systemic chemotherapy (n = 56, 50. 5%). The median freedom from progression was 3. 4 months. In multivariate analysis, patients who underwent more than 2 treatment modalities experienced significantly longer progression-free interval (1. 8 months vs. 7. 4 months, HR = 0. 20, p = 0. 038). Additionally, patients who underwent excision of the primary breast tumor displayed a tendency for longer progression-free interval (3. 1 months vs. 3. 4 months, HR = 0. 33, p = 0. 084). Patients with systemic inflammation index greater than 500 × 103/mm3 at the time of the diagnosis of LM exhibited shorter progression-free interval (3. 5 months vs. 2. 9 months, HR = 2. 88, p = 0. 056). There was no difference of progression-free interval according to treatment modalities. Conclusions: The freedom from progression of LM originating from breast cancer was found to be poor, exhibiting less than 4 months. A multimodal approach upon LM and high systemic inflammation index at the time of the diagnosis of LM demonstrated significant difference in prognosis. Further research is warranted to elucidate the clinical implications and develop optimized treatment strategie Citation Format: Suzy Kim, Choong-won Lee. Treatment outcome of leptomeningeal metastasis from breast cancer abstract. In: Proceedings of the AACR Special Conference on Brain Cancer; 2023 Oct 19-22; Minneapolis, Minnesota. Philadelphia (PA): AACR; Cancer Res 2024;84 (5 Suppl₁): Abstract nr A051.
Kim et al. (Mon,) studied this question.