In the past decade, our understanding of the roles of external beam
radiotherapy (EBRT) and stereotactic radiosurgery (SRS) in the management of
brain tumors has dramatically improved. To highlight the changes and contemporary treatment approaches, we review the indications and outcomes of ionizing radiation for benign intracranial
tumors and
brain metastases. For nonfunctioning
pituitary adenomas, SRS is able to achieve radiographic
tumor control in at least 90 % of cases. The rate of SRS-induced endocrine remission for functioning
pituitary adenomas depends on the
tumor subtype, but it is generally lower than the rate of radiographic
tumor control. The most common complications from
pituitary adenoma SRS treatment are
hypopituitarism and
cranial neuropathies. SRS has become the preferred treatment modality for
vestibular schwannomas and skull base
meningiomas less than 3 cm in size. Large
vestibular schwannomas and
meningiomas remain best managed with initial surgical resection or EBRT for surgically ineligible patients. For small to moderately sized
brain metastases, there has been a shift toward treatment of newly diagnosed patients with SRS alone due to similar local control rates compared with surgical resection. RCTs have shown combined SRS and whole brain
radiation therapy (WBRT) for
brain metastases to decrease rates of local and distant intracranial recurrence compared to SRS alone. However, the improved intracranial control comes at the expense of poorer neurocognitive outcomes and without prolonging overall survival. Therefore, WBRT is generally reserved for
salvage therapy. While EBRT has been frequently supplanted by SRS for the treatment
pituitary adenomas and
brain metastases, it still proves useful in selected cases of large lesions which are not amenable to surgical debulking or for those with widespread disease, poor performance status, and short life expectancy. In recent years, the scope of SRS has extended beyond the intracranial space to include extradural and intradural spinal
tumors.