Stereotactic body radiotherapy for spinal oligometastases: a review on patient selection and the optimal methodology

Abstract

Stereotactic body radiotherapy (SBRT) has excellent local control and low toxicity for spinal metastases and is widely performed for spinal oligometastases. However, its additional survival benefit to standard of care, including systemic therapy, is unknown because the results of large-scale randomized controlled trials regarding SBRT for oligometastases have not been reported. Consequently, the optimal patient population among those with spinal oligometastases and the optimal methodology for spine SBRT remain unclear. The present review article discusses two topics: evidence-based optimal patient selection and methodology. The following have been reported to be good prognostic factors: young age, good performance status, slow-growing disease with a long disease-free interval, minimal disease burden, and mild fluorodeoxyglucose accumulation in positron emission tomography. In addition, we proposed four measures as the optimal SBRT method for achieving excellent local control: (i) required target delineation; (ii) recommended dose fraction schedule (20 or 24 Gy in a single fraction for spinal oligometastases and 35 Gy in five fractions for lesions located near the spinal cord); (iii) optimizing dose distribution for the target; (iv) dose constraint options for the spinal cord.

Separation surgery followed by stereotactic ablative radiotherapy for metastatic epidural spinal cord compression: A systematic review and meta-analysis for local progression rate

“…Increasing fractionation makes it possible to escalate the minimum dose delivered to a gross tumor which can attribute local control. The previous studies indicated that higher doses in the same fraction scheme showed higher 2-years local control rate [36] , [37] . We concluded that the degree of separation obtained after separation surgery and the resulting maximum permissible dose for residual tumor not exceeding spinal cord dose tolerance are the main factors that determine the fraction of the postoperative SBRT scheme, and after deciding fraction, it is important for local control to give as much dose per fraction as possible.…”

The Importance of Radiation Planning Guidelines in Spinal Stereotactic Body Radiotherapy

“…Spinal SBRT is a favorable treatment modality for oligometastatic cases, particularly those limited to no more than three contiguous segments, provided the patients exhibit a good performance status and lack clinical or radiological signs of cord compression or spine instability [ 1 ]. Several studies have reported LC rates ranging between 85 and 90% [ 6 ].…”

“…Stereotactic body radiotherapy (SBRT) employing intensity-modulated radiotherapy and image-guidance techniques has become the standard therapy for spinal metastases. SBRT for the spine attains a high local control (LC) rate (1 year: 90%) and has low toxicity (0.2% rate of neurologic injury) [ 1 ].…”

Solid tumours showing oligoprogression to immune checkpoint inhibitors have the potential for abscopal effects

“…Oligometastatic disease, which generally presents with fewer than five metastases, is a prime candidate [ 17 , 18 ]. Radiotherapy for oligometastatic disease is largely beneficial for improving prognosis [ 19 – 21 ]. Recently, oligoprogressive disease has gained attention as the next target for radiotherapy.…”