Pachymeningeal seeding possible after brain metastases resection
medwireNews: Neurosurgical resection of brain metastases followed by stereotactic radiation can lead to pachymeningeal seeding outside of the stereotactic radiation field, according to findings reported in JAMA Oncology.
Among patients with newly diagnosed brain metastases, pachymeningeal seeding was seen in 36 of 318 participants who underwent neurosurgical resection followed by stereotactic radiation, compared with none of 870 patients who did not undergo surgery.
Of 428 individual neurosurgical resections carried out, 36 resulted in pachymeningeal seeding, giving an incidence of 8.4%. There was, however, no difference in leptomeningeal disease between the two groups.
A key risk factor for pachymeningeal seeding was prior radiation, which was associated with a significant 2.39-fold increased risk after adjusting for maximal unidimensional size prior to resection and primary disease histology.
Researcher Daniel Cagney (Brigham and Women’s Cancer Center, Boston, Massachusetts, USA) and colleagues describe their findings as showing “a unique pattern of intracranial progression in patients undergoing neurosurgical resection for a brain metastasis.”
Seeding was more common among patients with controlled versus uncontrolled or newly diagnosed extracranial disease at diagnosis, at 13.7% versus 3.6%, and it was seen in 30.6% of those with recursive partitioning analysis class I disease, which indicates an otherwise favorable prognosis.
The researchers describe these findings as concerning, and say they are “likely owing to the lower competing risk of systemic progression or death, and therefore [represent] a marked prognostic turn with significant clinical consequences for such patients.”
The team suggests that “discussion of [whole-brain radiotherapy] should be considered in patients with resection of a single brain metastasis, particularly if extracranial disease is absent and the competing risk of systemic death is thereby lower.”
Among the patients who experienced pachymeningeal seeding, 13% developed leptomeningeal failure and 16% developed new metastases within the brain parenchyma. Neurologic disease progression was the primary cause of death among the 36 patients with pachymeningeal disease who died, at a rate of 72%.
Most patients with pachymeningeal seeding were treated with salvage radiation – either stereotactic radiation (49.1%) or whole-brain radiotherapy (34.0%). And among these patients, stereotactic radiation was associated with a 51% reduced risk for death.
Although durable salvage of pachymeningeal seeding was uncommon, “a small percentage of patients achieved sustained disease control with radiotherapeutic approaches,” the researchers note.
They conclude: “Pachymeningeal seeding beyond the adjuvant stereotactic radiation field represents a substantial oncologic event in patients undergoing neurosurgical resection of a brain metastasis and warrants further evaluation in clinical studies.”
By Catherine Booth
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