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Radiosurgery of Central Nervous System Tumors and Arteriovenous Malformations


Clinical Pearls

  • Randomized controlled and prospective trials have established a survival advantage and high local control rates after stereotactic radiosurgery for metastatic disease to the CNS, including for up to 10 brain metastases.

  • Matched cohort studies comparing Gamma Knife radiosurgery to surgical resection of vestibular schwannomas report similar tumor control rates for small and medium-sized tumors. However, Gamma Knife radiosurgery reduces the rates of facial weakness (<1%), increases the higher likelihood of hearing preservation, and avoids open surgical complications.

  • Several prospective longitudinal studies report high control rates with minimal adverse radiation effects after stereotactic radiosurgery of benign tumors including meningiomas, schwannomas, pituitary adenomas, and paragangliomas, among others.

  • Multicenter cohort studies with long-term follow-up demonstrate favorable outcomes after stereotactic radiosurgery of arteriovenous malformations including low tissue toxicity and arteriovenous malformation obliteration rates of 50% to 85%.

Stereotactic radiosurgery (SRS) is a first-line management option for many CNS tumors as well as arteriovenous malformations (AVMs). It provides high tumor control rates, presents low toxicity to surrounding structures, and avoids morbidity and complications associated with surgical resection. Frame-based Gamma Knife radiosurgery can create highly conformal plans to irregularly shaped lesions with the assistance of high-resolution imaging and the delivery of up to 200 cobalt beams from multiple directions. Its high selectivity is a result of a steep falloff of radiation into the surrounding structures, thereby minimizing toxicity and increasing its safety.

The delivery of high-dose, single-fraction radiation induces single-strand and double-strand DNA breaks, which limit the repopulation of tumor cells. A key feature of radiosurgery is its dose heterogeneity, with higher central doses providing a potential radiobiologic advantage. A potential disadvantage of single-dose SRS compared to conventional fractionated radiotherapy is an inability to exploit cell cycle redistribution to maximize cell death or capitalize on reoxygenation in hypoxic tumor cells. Hypofractionated SRS may overcome these limitations, but clinical evidence of this result is needed.

This chapter summarizes radiosurgery techniques and outcomes, including control rates, common prescription doses, and potential adverse radiation effects (AREs) for the main indications for SRS including brain metastasis, vestibular schwannoma (VS), meningioma, pituitary adenoma, and AVM. However, SRS has an increasing role in the management of other CNS tumors not discussed in this chapter, including other schwannomas, glomus tumors, hemangiopericytomas, pineal tumors, hemangioblastomas, craniopharyngiomas, and gliomas, among others.

Central Nervous System Tumors

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