Fractionated Radiosurgery

Stereotactic radiosurgery (SRS) is a well-established treatment for patients with brain tumors. Single-fraction SRS offers definitive tumor local control for most benign brain tumors and may represent an effective treatment option for selected malignant tumors and brain metastases; however, its ability to deliver an effective and safe dose can be limited for larger tumors located in proximity to brain structures highly sensitive to radiation. Fractionated SRS has increasingly been used for lesions larger than 3 cm in size or located in proximity or within critical brain structures with the aim of improving the balance between tumor control and normal tissue toxicity over single-fraction SRS. Several published studies have reported excellent clinical outcomes and acceptable acute and long-term radiation-induced toxicity after fractionated SRS (2–5 fractions) delivered with currently available machines, including the Gamma Knife and modified linear accelerators. Although data support the use of doses around 24–35 Gy given in 3–5 fractions for relatively large tumors or those in close proximity to critical anatomic structures, future clinical trials are needed to definitively prove the advantages of fractionated SRS over single-fraction SRS. In addition, future research is needed to define the optimal radiation dose and fractionation for different tumor types. An update of clinical results of fractionated SRS for brain tumors is presented. The advantages and limits of the technique have been critically reviewed.