Optimal Management of Brainstem Metastases

A Narrative Review

Joan Y. Lee; Danielle A. Cunningham; Erin S. Murphy; Samuel T. Chao; John H. Suh

Disclosures

Chin Clin Oncol. 2022;11(2):15 

In This Article

Epidemiology

The literature has reported that 80–85% of brain metastases are located in the cerebral hemisphere, 10–15% in the cerebellum and 3–7% in the brainstem.[1–4] The lower incidence of brainstem metastases relative to other brain metastases is attributed to the small volume of the brainstem (less than 3% of the brain by weight) and greater distribution of arterial perfusion to the anterior circulation, which supplies the cerebral hemispheres, over the posterior circulation that supplies the brainstem and cerebellum. High resolution phase contrast magnetic resonance imaging (MRI) studies revealed that 72% of intracranial arterial perfusion is received through the internal carotid arteries (anterior circulation), while 28% is received through the vertebral arteries (posterior circulation).[5]

The pons is the most common location of brainstem metastasis, followed by the midbrain, and then the medulla.[6,7] The largest existing analysis of multicenter retrospective data reports that the most frequently associated primary malignancies are lung (44.9%, predominantly non-small cell), followed by breast (20.2%), melanoma (10%), renal cell/genitourinary (7.5%), and gastrointestinal (GI) cancers (4.5%). These incidences are similar to those found in a classical autopsy study of brainstem metastases (46.7% lung, 13.3% breast, 8.9% melanoma, 4.5% renal cell, 4.5% GI), as well as the incidences of primary malignancies for all brain metastases (50% lung cancer, predominantly non-small cell, 15% breast, 7% melanoma, 7% renal cell, and 6% GI).[2,4]

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