The aggregate of data pertaining to brain metastases suggests that optimal results are achievable with a 2-pronged approach that addresses both the specific focus (with surgery or radiosurgery) and the surrounding brain parenchymal tissue that may harbor micrometastases. Patterns of failure following treatment of metastases that arise in the posterior fossa have not been reliably defined. Although most would agree that radiosurgery alone is not sufficient treatment for focal metastases in the cerebellum, it may be possible to deliver less than WBI as an "expanded port" beyond the SRS volume.

The current study acknowledges that at least two therapeutic modalities are requisite for patients with cerebellar metastases but hypothesizes that it is unnecessary to extend the treatment of ostensibly uninvolved brain tissue beyond the limits of the posterior fossa. In so doing, it is hoped that the putative advantage derived from foregoing whole brain irradiation (e.g., reduction in neurocognitive impairment) will not be at the expense of excessive surpratentorial failure.