Pathological characteristics of spine metastases treated with high-dose single-fraction stereotactic radiosurgery

Abstract

<jats:sec> <jats:title>OBJECTIVE</jats:title> <jats:p>Spine radiosurgery is increasingly being used to treat spinal metastases. As patients are living longer because of the increasing efficacy of systemic agents, appropriate follow-up and posttreatment management for these patients is critical. Tumor progression after spine radiosurgery is rare; however, vertebral compression fractures are recognized as a more common posttreatment effect. The use of radiographic imaging alone posttreatment may makeit difficult to distinguish tumor progression from postradiation changes such as fibrosis. This is the largest series from a prospective database in which the authors examine histopathology of samples obtained from patients who underwent surgical intervention for presumed tumor progression or mechanical pain secondary to compression fracture. The majority of patients had tumor ablation and resulting fibrosis rather than tumor progression. The aim of this study was to evaluate tumor histopathology and characteristics of patients who underwent pathological sampling because of radiographic tumor progression, fibrosis, or collapsed vertebrae after receiving high-dose single-fraction stereotactic radiosurgery.</jats:p></jats:sec> <jats:sec> <jats:title>METHODS</jats:title> <jats:p>Between January 2005 and January 2014, a total of 582 patients were treated with linear accelerator–based single-fraction (18–24 Gy) stereotactic radiosurgery. The authors retrospectively identified 30 patients (5.1%) who underwent surgical intervention for 32 lesions with vertebral cement augmentation for either mechanical pain or instability secondary to vertebral compression fracture (n = 17) or instrumentation (n = 15) for radiographic tumor progression. Radiation and surgical treatment, histopathology, and long-term outcomes were reviewed. Survival and time to recurrence were calculated using the Kaplan-Meier method.</jats:p></jats:sec> <jats:sec> <jats:title>RESULTS</jats:title> <jats:p>The mean age at the time of radiosurgery was 59 years (range 36–80 years). The initial pathological diagnoses were obtained for all patients and primarily included radioresistant tumor types, including renal cell carcinoma in 7 (22%), melanoma in 6 (19%), lung carcinoma in 4 (12%), and sarcoma in 3 (9%). The median time to surgical intervention was 24.7 months (range 1.6–50.8 months). The median follow-up and overall survival for all patients were 42.5 months and 41 months (overall survival range 7–86 months), respectively. The majority of assessed lesions showed no evidence of tumor on pathological review (25 of 32, 78%), while a minority of lesions revealed residual tumor (7 of 32, 22%). The median survival for patients after tumor recurrence was 5 months (range 2–70 months).</jats:p></jats:sec> <jats:sec> <jats:title>CONCLUSIONS</jats:title> <jats:p>High-dose single-fraction radiosurgery is tumor ablative in the majority of instances. In a minority of cases, tumor persists and salvage treatments should be considered.</jats:p></jats:sec>

Randomized phase II trial evaluating pain response in patients with spinal metastases following stereotactic body radiotherapy versus three-dimensional conformal radiotherapy

“…The hypothesis that ablative dosing leads to improved tumor control is not new. The application of higher biological doses was preferred for radioresistant tumors, those previously irradiated, and oligometastatic disease [9,16,25]. Experiences with singlefraction SBRT (24 Gy) is limited to a few datasets.…”

“…Approximately one third of cancer patients will develop bone metastases, approximately two thirds of which involve the vertebral column, most commonly at the thoracic and lumbar levels [1,2]. Conventionally fractionated 3D-conformal radiotherapy (3DCRT) is a well-recognized palliative treatment for painful bone metastases [3][4][5][6][7][8][9][10][11][12][13][14]. Comprehensive meta-analyses by Sze et al and Wu et al have provided consistent data regarding pain response after conventional external beam radiotherapy [13,14].…”

Hybrid surgery–radiosurgery therapy for metastatic epidural spinal cord compression: A prospective evaluation using patient-reported outcomes

“…Reliance on SRS to provide local tumor control has allowed surgeons to decrease the extent of surgical intervention, thereby minimizing the risk of complications and systemic therapy interruption. Spinal SRS has been shown to be a tumor ablative treatment 18 and provide durable and consistent tumor control, with reports of histology-independent 98% local control at 4-year follow-up. 19 Separation surgery followed by SRS has been previously shown to be an effective treatment strategy providing a greater than 95% control rate, for previously considered radioresistant tumors in a retrospective review of 186 cases.…”

Imaging response assessment following stereotactic body radiotherapy for solid tumour metastases of the spine: Current challenges and future directions

“…In order to accurately characterise imaging findings as being in keeping with tumour response, tumour progression, pseudoprogression, and VCF either secondary to tumour or treatment, radio‐pathologic studies are needed. MSKCC reported in 2017 on 30 patients (out of a cohort of 582 who underwent single‐fraction spine SRT) who underwent surgical instrumentation for either VCF, instability or tumour progression 46 . Overall, they found that active tumour was present in only 22% of specimens (60% of surgical intervention cases and 5% of vertebral augmentation cases).…”