Evolving Techniques in CNS Radiosurgery: Historical, Contemporary and Future Directions
Stereotactic radiosurgery (SRS) remains an effective treatment for brain metastases with excellent local control (LC) and minimal toxicity. There are many case studies that now demonstrate excellent outcomes in complex cases. There is also increasing evidence in the use of SRS in benign conditions too, that show control rates similar to that of surgery, with low morbidity. And advances in spinal SRS and SBRT demonstrate a heightened interest in oligometastatic disease with recent studies reporting efficacy and optimized tumor control in these patients.
Accuray recently hosted a symposium at ASTRO 2024 inviting four renowned speakers to talk about their experiences in this area.
Efficacy of radiosurgery in treating benign brain lesion by Steven. D Chang, M.D from Stanford University, CA
Since 2018 to 2024, Stanford University has treated over 12,000 CNS patients with SRS. Benign tumors make up a proportion of these numbers including meningiomas, vestibular schwannoma, parangliomas, hemangioblastomas and ependymoma. Dr Steven Chang reported the trends in radiosurgery and how its use is increasing for the use of meningiomas compared to surgery, and this is similar for other benign tumors too. Radiosurgery alone is becoming a popular choice where SRS can achieve greater than 90% local control for many benign brain tumors including large lesions. It can provide a non-surgical option with minimized risks compared to traditional surgery with many patients experiencing stabilization or improvement in clinical symptoms post treatment.
Innovative radiotherapeutic techniques for multiple brain metastases by Vinai Gondi, M.D. from Northwestern Medical Group, Chicago
The basic principles of why radiotherapy is so important for brain metastases is that:
- The brain can be penetrated by radiation without being restricted by the blood brain barrier
- The tumoricidal effect of radiotherapy is relatively mechanism-agnostic, meaning there are many ways to get to the same endpoint in a very effective manner.
Radiotherapy is the central modality in neuro-oncology for primary and metastatic brain tumors. Dr Vinai Gondi reports on a case of a 62-year-old women who was diagnosed with 10 brain metastases after a history of left leg weakness and seizure activity. Systemic imaging finds a squamous cell carcinoma of the lung. He discusses the treatment options that are available with radiation therapy including post operative single fraction SRS, whole brain radiotherapy (WBRT), fractionated SRS and hippocampal-avoidant WBRT (HA-WBRT) and their associated local control and toxicities.
Case studies in complex brain metastases management by Lawrence Kleinberg M.D. from The Johns Hopkins University School of Medicine, Baltimore
In this presentation Dr Lawrence Kleinberg reports on a 10 year case study of a 54 year old woman with T3N1M1 triple negative BRCA breast cancer. She presented with one femur metastases and was treated with palliative radiation therapy followed by a dose of intensive AC chemotherapy. From mastectomy the patient was found to have had a complete response in the breast and lymph nodes, continuing with post operative radiation therapy and chemotherapy. 1 year later she presented with a temporal lobe metastasis that was resected and followed by post operative SRS. Within a 10-year period the patient continued to recur with further brain metastases but was managed with surgery and SRS. This is an incredible case study of a patient from 99 months since the first metastases, having 7 neurosurgeries, 6 courses of robotic stereotactic radiosurgery, that to this day has maintained a good quality of life, good cognitive function and lives independently with no other systemic recurrence.
Optimizing tumor outcomes while minimizing toxicity following spinal stereotactic body radiation therapy by Kristin Redmond, M.D., M.P.H. from The Johns Hopkins University School of Medicine, Baltimore
SBRT represents one of the most critical advancements in the management of spinal metastases over the last 2 decades. It has been driven by advancements in technology to deliver truly ablative doses to the target while minimizing dose to the surrounding tissues, delivering sub-millimeter accuracy. Dr Kristin Redmond, reports on some of the first randomized studies on spinal cord radiotherapy using conventional and SBRT treatment regimens. She goes onto discuss target delineation being a critical component when delivering treatment with sub-millimeter accuracy. Consensus guidelines help determine target delineation for various intact, preoperative and post operative situations and researchers have found significantly better control when these consensus guidelines are followed. SBRT acts as a main tool to control cancer, reserving surgery for decompression of epidural disease or surgical stabilization. In conclusion, improvements in radiation therapy technology are allowing increasingly precise techniques with excellent local control and low toxicity.
If you want to learn more, you can watch the recording of the Accuray Symposium HERE
