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Cancer research

Focal Leptomeningeal Extension in Brain Metastases: A Novel Entity

Strategic Insights

— 2 min read

Focal leptomeningeal extension, a newly identified entity, has been found to display patterns of intracranial failure similar to parenchymal brain metastases. Researchers at the Dana-Farber Cancer Institute conducted a study to assess whether patients with focal leptomeningeal extension can be managed with stereotactic radiation without excess development of marginal recurrences or subsequent classical leptomeningeal disease. The study analyzed data from 796 patients with brain metastases, of which 138 (17.3%) displayed evidence of focal leptomeningeal extension. The results showed that patients with focal leptomeningeal extension did not display excess local recurrences or subsequent classical leptomeningeal disease, suggesting that stereotactic approaches may be viable in this population.

Key Takeaways:

  • 796 patients with brain metastases were assessed for focal leptomeningeal extension (fLME), defined as isolated leptomeningeal extension of an intact brain metastasis without cytologic or radiographic evidence of classical leptomeningeal disease.
  • 138 (17.3%) patients displayed evidence of fLME, corresponding to 185 of 2,354 (7.9%) brain metastases.
  • Patients with fLME did not display excess local recurrences (1-year rate: 4.5% vs. 8.2%, respectively, p = 0.14) or subsequent classical leptomeningeal disease (1-year rate: 5.2% vs 5.2%, p = 0.99).
  • Stereotactic radiation was used to treat 185 brain metastases with fLME, with no excess marginal recurrences or subsequent classical leptomeningeal disease.
  • The study concludes that stereotactic approaches, such as stereotactic radiation, may be viable in patients with brain metastases and focal leptomeningeal extension.
  • Lianne Kraemer, Breast Oncology Program, Dana-Farber Cancer Institute, Boston, Massachusetts, United States, is the lead researcher of this study.
  • Additional authors include Nayan Lamba, Rifaquat Rahman, Shyam Tanguturi, Daniel N. Cagney, Paul J. Catalano, Hesham Elhalawani, Daphne A. Haas-Kogan, Patrick Y. Wen, and Ayal A. Aizer.

Statistics:

  • 796 patients with brain metastases were assessed for focal leptomeningeal extension (fLME).
  • 138 (17.3%) patients displayed evidence of fLME, corresponding to 185 of 2,354 (7.9%) brain metastases.
  • 1-year local recurrence rate: 4.5% for patients with fLME vs. 8.2% for patients without fLME (p = 0.14).
  • 1-year classical leptomeningeal disease rate: 5.2% for patients with fLME vs. 5.2% for patients without fLME (p = 0.99).
  • 185 brain metastases with fLME were treated with stereotactic radiation.

Sources:

  • NewsRx. Research from Dana-Farber Cancer Institute Reveals New Findings on Brain Metastasis (Characterization of Focal Leptomeningeal Extension in Patients with Brain Metastases: A Novel Entity). Pain & Central Nervous System Week. October 20, 2025; p 1383.
  • Neuro-Oncology, 2025.
  • Oxford Univ Press Inc, Journals Dept, 2001 Evans Rd, Cary, NC 27513, USA.

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