Postoperative Stereotactic Body Radiation Therapy, Then Observe

This patient presented with high-grade epidural disease (Bilsky grade 2 and 3) and underwent urgent surgical decompression with subsequent downgrading of epidural disease on imaging. 1 Pinkawa M. Spinal cord reirradiation-balancing benefit against risks. Int J Radiat Oncol Biol Phys. 2021; 109: 312-313 Abstract Full Text Full Text PDF PubMed Scopus (3) Google Scholar Postoperative spine stereotactic body radiation therapy (SBRT) experience has shown that a postoperative epidural Bilsky grade of 0 or 1 is a significant predictor of local control. 2 Al-Omair A. Masucci L. Masson-Cote L. et al. Surgical resection of epidural disease improves local control following postoperative spine stereotactic body radiotherapy. Neuro Oncol. 2013; 15: 1413-1419 Crossref PubMed Scopus (113) Google Scholar In the absence of biomarkers or next-generation molecular diagnostics we cannot determine with certainty which patients with oligometastatic disease will benefit from metastasis-directed treatment with SBRT. However, this is a young patient with oligometastatic disease, limited tumor burden, long disease-free interval, favorable histology, and life expectancy with potential future systemic options; as such, we would treat with SBRT to optimize local control. We would not offer conventional palliative external beam radiation therapy in this setting. 3 Chow E. van der Linden Y.M. Roos D. et al. Single versus multiple fractions of repeat radiation for painful bone metastases: A randomised, controlled, non-inferiority trial. Lancet Oncol. 2014; 15: 164-171 Abstract Full Text Full Text PDF PubMed Scopus (187) Google Scholar ,4 Myrehaug S. Sahgal A. Hayashi M. et al. Reirradiation spine stereotactic body radiation therapy for spinal metastases: A systematic review. J Neurosurg Spine. 2017; 27: 428-435 Crossref PubMed Scopus (74) Google Scholar Given the dearth of evidence using radiosensitizers, we would not recommend their use due to concerns about an increased risk of myelopathy, particularly in the context of reirradiation. Treatment volumes would include the entire extent of the pre- and postoperative disease and the adjacent anatomic segment, as per the evidence-based consensus contouring guidelines. 5 Redmond K.J. Robertson S. Lo S.S. et al. Consensus contouring guidelines for postoperative stereotactic body radiation therapy for metastatic solid tumor malignancies to the spine. Int J Radiat Oncol Biol Phys. 2017; 97: 64-74 Abstract Full Text Full Text PDF PubMed Scopus (63) Google Scholar Optimal dose in this setting is still unknown. We would treat with 24 Gy in 2 fractions or 35 Gy in 5 fractions, a prescription similar to that given for the intact vertebrae. In the setting of reirradiation, a total thecal sac maximum point EQD2 of approximately 70 Gy2/2 with a minimum time interval to reirradiation of at least 5 months has been suggested to be clinically safe. 6 Sahgal A. Ma L. Weinberg V. et al. Reirradiation human spinal cord tolerance for stereotactic body radiotherapy. Int J Radiat Oncol Biol Phys. 2012; 82: 107-116 Abstract Full Text Full Text PDF PubMed Scopus (164) Google Scholar