Roman O Kowalchuk1, Ajay Niranjan2, Cheng-Chia Lee3, Huai-Che Yang3, Roman Liscak4, Khumar Guseynova4, Manjul Tripathi5, Narendra Kumar6, Selcuk Peker7, Yavuz Samanci7, Judith Hess8, Veronica Chiang8, Christian Iorio-Morin9, David Mathieu9, Stylianos Pikis10, Zhishuo Wei2, L Dade Lunsford2, Daniel M Trifiletti11, Jason P Sheehan10. 1. Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota. Electronic address: Kowalchuk.Roman@mayo.edu. 2. Department of Neurological Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania. 3. Department of Neurosurgery, Neurological Institute, Taipei Veteran General Hospital, Taipei, Taiwan; National Yang-Ming University School of Medicine, Taipei, Taiwan. 4. Stereotactic and Radiation Neurosurgery, Na Homolce Hospital, Prague, Czech Republic. 5. Department of Neurosurgery, Postgraduate Institute of Medical Education and Research, Chandigarh, India. 6. Department of Radiotherapy, Postgraduate Institute of Medical Education and Research, Chandigarh, India. 7. Department of Neurosurgery, Koc University School of Medicine, Istanbul, Turkey. 8. Department of Neurosurgery, Yale New Haven Hospital, New Haven, Connecticut. 9. Department of Neurosurgery, Université de Sherbrooke, Centre de recherche du CHUS, Quebec, Canada. 10. Department of Neurosurgery, University of Virginia Health System, Charlottesville, Virginia. 11. Mayo Clinic, Department of Radiation Oncology, Mayo Clinic, Jacksonville, Florida.
Abstract
PURPOSE: Brain metastases represent a major indication for stereotactic radiosurgery (SRS), but further study is needed regarding repeat SRS (SRS2) after local or marginal recurrence after prior SRS (SRS1). We report local tumor control (LC) after SRS2 and identify predictors of radiation necrosis (RN) and symptomatic RN (SRN). METHODS AND MATERIALS: Patients had biopsy-proven non-small cell lung cancer and at least 1 brain metastasis previously treated with SRS. SRS2 was performed from 2015 to 2020 and required overlap of the prescription isodose lines with those from SRS1. Patients treated with preoperative SRS were excluded. Primary endpoints were LC by Response Assessment in Neuro-oncology criteria, RN, and SRN. RESULTS: From 8 institutions, 102 patients with 123 treated lesions were included. SRS2 was performed at a median 12 months after SRS1. SRS2 delivered a median 18 Gy (interquartile range [IQR], 16-18) margin dose to the 50% (IQR, 50%-70%) isodose line, maximum dose of 30.5 Gy (IQR, 25.0-36.0), and V12Gy of 3.38 cm3 (IQR, 0.83-7.64). One-year and 2-year LC were 79% and 72%, respectively. Local tumor control was improved with tumor volume ≤1 cm3 (P < .005). There were 25 (20%) cases of RN and 9 (7%) cases of SRN. For SRS1 and SRS2, SRN rates were higher with maximum doses ≥40 Gy or SRS2 V12Gy >9 cm3 (P < .025 for each). SRS1 and SRS2 maximum dose ≥40 Gy was also predictive of increased RN (P < .05 for each). Prior immunotherapy was not predictive of RN or SRN. CONCLUSIONS: Repeat SRS afforded a high rate of local tumor control and a low rate of SRN. At SRS2, V12Gy ≤9 cm3 and maximum dose <40 Gy may reduce the risks of RN and SRN. These results are most applicable to lesions with approximately 1 cm3 volume and 1-year interval between SRS courses.
PURPOSE: Brain metastases represent a major indication for stereotactic radiosurgery (SRS), but further study is needed regarding repeat SRS (SRS2) after local or marginal recurrence after prior SRS (SRS1). We report local tumor control (LC) after SRS2 and identify predictors of radiation necrosis (RN) and symptomatic RN (SRN). METHODS AND MATERIALS: Patients had biopsy-proven non-small cell lung cancer and at least 1 brain metastasis previously treated with SRS. SRS2 was performed from 2015 to 2020 and required overlap of the prescription isodose lines with those from SRS1. Patients treated with preoperative SRS were excluded. Primary endpoints were LC by Response Assessment in Neuro-oncology criteria, RN, and SRN. RESULTS: From 8 institutions, 102 patients with 123 treated lesions were included. SRS2 was performed at a median 12 months after SRS1. SRS2 delivered a median 18 Gy (interquartile range [IQR], 16-18) margin dose to the 50% (IQR, 50%-70%) isodose line, maximum dose of 30.5 Gy (IQR, 25.0-36.0), and V12Gy of 3.38 cm3 (IQR, 0.83-7.64). One-year and 2-year LC were 79% and 72%, respectively. Local tumor control was improved with tumor volume ≤1 cm3 (P < .005). There were 25 (20%) cases of RN and 9 (7%) cases of SRN. For SRS1 and SRS2, SRN rates were higher with maximum doses ≥40 Gy or SRS2 V12Gy >9 cm3 (P < .025 for each). SRS1 and SRS2 maximum dose ≥40 Gy was also predictive of increased RN (P < .05 for each). Prior immunotherapy was not predictive of RN or SRN. CONCLUSIONS: Repeat SRS afforded a high rate of local tumor control and a low rate of SRN. At SRS2, V12Gy ≤9 cm3 and maximum dose <40 Gy may reduce the risks of RN and SRN. These results are most applicable to lesions with approximately 1 cm3 volume and 1-year interval between SRS courses.