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Task Group 101 of the AAPM has prepared this report for medical physicists, clinicians, and therapists in order to outline the best practice guidelines for the external-beam radiation therapy technique referred to as stereotactic body radiation therapy (SBRT). The task group report includes a review of the literature to identify reported clinical findings and expected outcomes for this treatment modality. Information is provided for establishing a SBRT program, including protocols, equipment, resources, and QA procedures. Additionally, suggestions for developing consistent documentation for prescribing, reporting, and recording SBRT treatment delivery is provided.

Object. The authors report data concerning the safety, effectiveness, and patterns of failure obtained in a Phase I/II study of stereotactic body radiotherapy (SBRT) for spinal metastatic tumors. Methods. Sixty-three cancer patients underwent near-simultaneous computed tomography–guided SBRT. Spinal magnetic resonance imaging was conducted at baseline and at each follow-up visit. The National Cancer Institute Common Toxicity Criteria 2.0 assessments were used to evaluate toxicity. Results. The median tumor volume of 74 spinal metastatic lesions was 37.4 cm3 (range 1.6–358 cm3). No neuropathy or myelopathy was observed during a median follow-up period of 21.3 months (range 0.9–49.6 months). The actuarial 1-year tumor progression–free incidence was 84% for all tumors. Pattern-of-failure analysis showed two primary mechanisms of failure: 1) recurrence in the bone adjacent to the site of previous treatment, and 2) recurrence in the epidural space adjacent to the spinal cord. Grade 3 or 4 toxicities were limited to acute Grade 3 nausea, vomiting, and diarrhea (one case); Grade 3 dysphagia and trismus (one case); and Grade 3 noncardiac chest pain (one case). There was no subacute or late Grade 3 or 4 toxicity. Conclusions. Analysis of the data obtained in the present study supports the safety and effectiveness of SBRT in cases of spinal metastatic cancer. The authors consider it prudent to routinely treat the pedicles and posterior elements using a wide bone margin posterior to the diseased vertebrae because of the possible direct extension into these structures. For patients without a history of radiotherapy, more liberal spinal cord dose constraints than those used in this study could be applied to help reduce failures in the epidural space.

Summary Background This study investigated the clinical benefit of using hypofractionated stereotactic body radiotherapy (SBRT) to manage spinal metastases in patients with cancer and to reduce cancer-related symptoms. Methods Cancer patients (n=149) with mechanically stable, non–cord-compressing, spinal metastases (n=166) were treated by SBRT in a phase I/II study. Patients received a total dose of 27–30 Gy, typically in three fractions. Symptoms were measured repeatedly by the Brief Pain Inventory (BPI) and the M. D. Anderson Symptom Inventory (MDASI). The primary endpoint was to establish the safety, feasibility, and efficacy of using a CT-on-Rails or Trilogy Stereotactic Spine Radiation Therapy system to treat spinal and paraspinal tumors and to document pain relief and toxicity associated with such treatment. Symptom outcomes were estimated according to protocol using descriptive analysis and ordinal regression modeling. This is the final report for the completed enrollment and follow-up. Findings The median follow-up time was 15·9 (interquartile range 9·5–30·3) months and the mean was 20·9 (SD=17·1) months. The actuarial tumor progression-free survival rates at one year and two years post-SBRT were 80·5% and 72·4%, respectively. Patients reported significant MDASI pain reduction (p=0·00003) during the six months post-SBRT. Patients reporting no pain from bone metastases on the BPI increased from 39/149 (26·2%) before SBRT to 55/102 (53·9%) six months post-SBRT (p<0·0001). BPI pain reduction from baseline to four weeks post-SBRT was clinically meaningful (effect size=0·47, p<0·01). These improvements were accompanied by significant reduction in opioid use during the six months post-SBRT (p<0·05) and a significant reduction in MDASI symptom interference with daily life (p<0·01).. Only a few instances of nonneurological grade 3 toxicities occurred (one report each of nausea, vomiting, diarrhea, fatigue, dysphagia, neck pain, diaphoresis, two reports of pain associated with severe tongue edema and trismus, and 3 reports of noncardiac chest pain). No grade 4 toxicities occurred. Interpretation SBRT is an effective primary or salvage treatment of mechanically stable spinal metastasis. Significant reduction in patient-reported pain and other symptoms was evident six months post-SBRT, along with satisfactory progression-free survival and no late spinal cord toxicities.

Surgery and radiosurgery are effective treatment modalities for brain metastasis. To compare the results of these treatment modalities, the authors followed 13 patients treated by radiosurgery and 62 patients treated by surgery who were retrospectively matched. Patients were matched according to the following criteria: histological characteristics of the primary tumor, extent of systemic disease, preoperative Karnofsky Performance Scale score, time to brain metastasis, number of brain metastases, and patient age and sex. For patients treated by radiosurgery, the median size of the treated lesion was 1.96 cm3 (range 0.41-8.25 cm3) and the median dose was 20 Gy (range 12-22 Gy). The median survival was 7.5 months for patients treated by radiosurgery and 16.4 months for those treated by surgery; this difference was found to be statistically significant using both univariate (p = 0.0018) and multivariate (p = 0.0009) analyses. The difference in survival was due to a higher rate of mortality from brain metastasis in the radiosurgery group than in the surgery group (p < 0.0001) and not due to a difference in the rate of death from systemic disease (p = 0.28). Log-rank analysis showed that the higher mortality rate found in the radiosurgery group was due to a greater progression rate of the radiosurgically treated lesions (p = 0.0001) and not due to the development of new brain metastasis (p = 0.75). On the basis of their data, the authors conclude that surgery is superior to radiosurgery in the treatment of brain metastasis. Patients who undergo surgical treatment survive longer and have a better local control. The data lead the authors to suggest that the indications for radiosurgery should be limited to surgically inaccessible metastatic tumors or patients in poor medical condition. Surgery should remain the treatment of choice whenever possible.