Single Brain Metastasis

Abstract

The management of single brain metastases has evolved substantially over the last decade. The advent of triple-dose contrast-enhanced MRI scans has improved the radiologists' capacity to resolve small tumors, and, thereby, has resulted in a declining percentage of brain metastases classified as single. Only 25% to 30% of brain metastases are single; single brain metastases in the absence of systemic metastases are termed solitary. Randomized trials suggest that patients not in imminent danger of herniation are best managed initially with dexamethasone 2 to 4 mg administered orally twice daily. The routine use of prophylactic anticonvulsants is discouraged. Patients with refractory progressive systemic tumor likely to prove fatal within 3 to 6 months should receive fractionated whole brain radiotherapy. Patients with highly radiosensitive primary tumors such as small cell lung cancer, lymphoma, and germinoma should also receive whole brain radiotherapy. Patients with inactive or controllable systemic cancer and good performance status benefit from the addition of local strategies like surgery or radiosurgery to whole brain radiotherapy. Although surgery and radiosurgery have not been compared in a randomized controlled trial, data suggest that results are similar. Consequently, for most metastases that fall within the size constraints of radiosurgery (3.5 cm or smaller in diameter), radiosurgery is preferred for its relatively noninvasive nature. Patients with larger or cystic tumors, with obstructive hydrocephalus, or neurologic instability despite corticosteroids are best treated with craniotomy. Fractionated whole brain radiation following surgical or radiosurgical management of single brain metastasis appears to decrease the risk of recurrent brain metastasis, although it has not been shown to improve survival. We recommend its use in most patients, although patients with tumors likely to be highly resistant to fractionated radiotherapy or at high risk of radiation neurotoxicity may reasonably defer its use.