Radiosurgery for Postoperative Metastatic Surgical Cavities: ISRS Practice Guidelines
Delhi: The International Stereotactic Radiosurgery Society (ISRS) has released clinical guidance on the delivery of postoperative radiosurgery for brain metastatic surgical cavities.
The purpose of the guideline, published in the International Journal of Radiation Oncology, Biology, Physics, is to summarize the literature specific to single-fraction stereotactic radiosurgery (SRS) and multiple-fraction stereotactic radiation therapy (SRT) for postoperative brain metastases resection cavities and to present practice recommendations on behalf of the ISRS.
Key recommendations include:
- After surgery for a brain metastasis, postoperative SRS is preferred over observation due to superior local control.
- For patients with 1 resected brain metastasis, ECOG performance status of 0-2, and a resection cavity measuring <5 cm, postoperative SRS to the resection cavity is recommended to minimize cognitive toxicity compared with whole-brain radiation therapy.
- Target volume should include the resection cavity and entire surgical tract with consideration to expand the clinical target volume to include a 5-10 mm expansion beyond the preoperative tumor location along bone flap in those tumors contacting the dura preoperatively, while respecting anatomic barriers, and a 1-5 mm expansion along sinuses for tumors contacting a sinus preoperatively. In addition, a 2-3 mm radial expansion to PTV should be considered.
- Prescription doses of approximately 30-50 Gy EQD210, 50-70 EQD25, and 70-90 EQD22, have been associated with reasonable local control, but formal comparative studies are warranted. Emerging data suggest single-fraction treatment without dose de-escalation is appropriate in cavities <2 cm in size and that fractionated regimens may provide superior local control compared with single-fraction SRS in patients with large metastases greater than 2.5-3 cm.
- The consent process for brain metastases surgery should include a discussion of the risk of surgical dissemination of tumor manifesting as leptomeningeal disease.
"Although randomized data raise concern for poorer local control after resection cavity SRS than WBRT, these findings may be driven by factors such as conservative prescription doses used in the SRS arm," wrote the authors. "Retrospective studies suggest high rates of local control after single-fraction SRS and hypofractionated SRT for postoperative brain metastases. With a superior neurocognitive profile and no survival disadvantage to withholding WBRT, the ISRS recommends SRS as first-line treatment for eligible postoperative patients."
"Emerging data suggest that fractionated SRT may provide superior local control compared with single-fraction SRS, in particular, for large tumor cavity volumes/diameters and potentially for patients with a preoperative diameter greater than 2.5 cm," they concluded.
Reference:
"Stereotactic Radiosurgery for Postoperative Metastatic Surgical Cavities: A Critical Review and International Stereotactic Radiosurgery Society (ISRS) Practice Guidelines," is published in the International Journal of Radiation Oncology, Biology, Physics.
