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Vikram B. Chakravarthy, Hammad A. Khan, Shaarada Srivatsa, Todd Emch, Samuel T. Chao, and Ajit A. Krishnaney

OBJECTIVE

Separation surgery followed by spine stereotactic radiosurgery (SSRS) has been shown to achieve favorable rates of local tumor control and patient-reported outcomes in patients with metastatic epidural spinal cord compression (MESCC). However, rates and factors associated with adjacent-level tumor progression (ALTP) in this population have not yet been characterized. The present study aimed to identify factors associated with ALTP and examine its association with overall survival (OS) in patients receiving surgery followed by radiosurgery for MESCC.

METHODS

Thirty-nine patients who underwent separation surgery followed by SSRS for MESCC were identified using a prospectively collected database and were retrospectively reviewed. Radiological measurements were collected from preoperative, postoperative, and post-SSRS MRI. Statistical analysis was conducted using the Kaplan-Meier product-limit method and Cox proportional hazards test. Subgroup analysis was conducted for patients who experienced ALTP into the epidural space (ALTP-E).

RESULTS

The authors’ cohort included 39 patients with a median OS of 14.7 months (range 2.07–96.3 months). ALTP was observed in 16 patients (41.0%) at a mean of 6.1 ± 5.4 months postradiosurgery, of whom 4 patients (10.3%) experienced ALTP-E. Patients with ALTP had shorter OS (13.0 vs 17.1 months, p = 0.047) compared with those without ALTP. Factors associated with an increased likelihood of ALTP included the amount of bone marrow infiltrated by tumor at the index level, amount of residual epidural disease following separation surgery, and prior receipt of radiotherapy at the index level (p < 0.05). Subgroup analysis revealed that primary tumor type, amount of preoperative epidural disease, time elapsed between surgery and radiosurgery, and prior receipt of radiotherapy at the index level were significantly associated with ALTP-E (p < 0.05).

CONCLUSIONS

To the authors’ knowledge, this study is the first to identify possible risk factors for ALTP, and they suggest that it may be associated with shorter OS in patients receiving surgery followed by radiosurgery for MESCC. Future studies with higher power should be conducted to further characterize factors associated with ALTP in this population.

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J. Bradley Elder and E. Antonio Chiocca

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Jacob A. Miller, Ehsan H. Balagamwala, Samuel T. Chao, Todd Emch, John H. Suh, Toufik Djemil, and Lilyana Angelov

OBJECTIVE

The objective of this study was to define symptomatic and radiographic outcomes following spine stereotactic radiosurgery (SRS) for the treatment of multiple myeloma.

METHODS

All patients with pathological diagnoses of myeloma undergoing spine SRS at a single institution were included. Patients with less than 1 month of follow-up were excluded. The primary outcome measure was the cumulative incidence of pain relief after spine SRS, while secondary outcomes included the cumulative incidences of radiographic failure and vertebral fracture. Pain scores before and after treatment were prospectively collected using the Brief Pain Inventory (BPI), a validated questionnaire used to assess severity and impact of pain upon daily functions.

RESULTS

Fifty-six treatments (in 38 patients) were eligible for inclusion. Epidural disease was present in nearly all treatment sites (77%). Moreover, preexisting vertebral fracture (63%), thecal sac compression (55%), and neural foraminal involvement (48%) were common. Many treatment sites had undergone prior local therapy, including external beam radiation therapy (EBRT; 30%), surgery (23%), and kyphoplasty (21%). At the time of consultation for SRS, the worst, current, and average BPI pain scores at these treatment sites were 6, 4, and 4, respectively. The median prescription dose was 16 Gy in a single fraction. The median clinical follow-up duration after SRS was 26 months. The 6- and 12-month cumulative incidences of radiographic failure were 6% and 9%, respectively. Among painful treatment sites, 41% achieved pain relief adjusted for narcotic usage, with a median time to relief of 1.6 months. The 6- and 12-month cumulative incidences of adjusted pain progression were 13% and 15%, respectively. After SRS, 1-month and 3-month worst, current, and average BPI scores all significantly decreased (p < 0.01). Vertebral fracture occurred following 12 treatments (21%), with an 18% cumulative incidence of fracture at 6 and 12 months. Two patients (4%) developed pain flare following spine SRS.

CONCLUSIONS

This study reports the largest series of myeloma lesions treated with spine SRS. A rapid and durable symptomatic response was observed, with a median time to pain relief of 1.6 months. This response was durable among 85% of patients at 12 months following treatment, with 91% local control. The efficacy and minimal toxicity of spine SRS is likely related to the delivery of ablative and conformal radiation doses to the target. SRS should be considered with doses of 14–16 Gy in a single fraction for patients with multiple myeloma and limited spinal disease, myelosuppression requiring “marrow-sparing” radiation therapy, or recurrent disease after EBRT.

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E. Emily Bennett, Camille Berriochoa, Ghaith Habboub, Scott Brigeman, Samuel T. Chao, and Lilyana Angelov

Stereotactic radiosurgery (SRS) has emerged as a treatment option for patients with spinal metastatic disease. Although SRS has been shown to be successful in a multitude of extradural metastatic tumors causing cord compression, very few cases of intradural treatment have been reported. The authors present a rare case of an intradural extramedullary metastatic small cell lung cancer lesion to the cervical spine resulting in cord compression in an area that had also been extensively pretreated with conventional external-beam radiation therapy. The patient underwent successful SRS to this metastatic site, with rapid and complete resolution of his lesion.

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Veronica L. Chiang, Samuel T. Chao, Constantin Tuleasca, Matthew C. Foote, Cheng-chia Lee, David Mathieu, Hany Soliman, and Arjun Sahgal

In order to determine what areas of research are a clinical priority, a small group of young Gamma Knife investigators was invited to attend a workshop discussion at the 19th International Leksell Gamma Knife Society Meeting. Two areas of interest and the need for future radiosurgical research involving multiple institutions were identified by the young investigators working group: 1) the development of additional imaging sequences to guide the understanding, treatment, and outcome tracking of diseases such as tremor, radiation necrosis, and AVM; and 2) trials to clarify the role of hypofractionation versus single-fraction radiosurgery in the treatment of large lesions such as brain metastases, postoperative cavities, and meningiomas.

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Mayur Sharma, Jason L. Schroeder, Paul Elson, Antonio Meola, Gene H. Barnett, Michael A. Vogelbaum, John H. Suh, Samuel T. Chao, Alireza M. Mohammadi, Glen H. J. Stevens, Erin S. Murphy, and Lilyana Angelov

OBJECTIVE

Glioblastoma (GBM) is the most malignant form of astrocytoma. The average survival is 6–10 months in patients with recurrent GBM (rGBM). In this study, the authors evaluated the role of stereotactic radiosurgery (SRS) in patients with rGBMs.

METHODS

The authors performed a retrospective review of their brain tumor database (1997–2016). Overall survival (OS) and progression-free survival (PFS) after salvage SRS were the primary endpoints evaluated. Response to SRS was assessed using volumetric MR images.

RESULTS

Fifty-three patients with rGBM underwent salvage SRS targeting 75 lesions. The median tumor diameter and volume were 2.55 cm and 3.80 cm3, respectively. The median prescription dose was 18 Gy (range 12–24 Gy) and the homogeneity index was 1.90 (range 1.11–2.02). The median OS after salvage SRS was estimated to be 11.0 months (95% CI 7.1–12.2) and the median PFS after salvage SRS was 4.4 months (95% CI 3.7–5.0). A Karnofsky Performance Scale score ≥ 80 was independently associated with longer OS, while small tumor volume (< 15 cm3) and less homogeneous treatment plans (homogeneity index > 1.75) were both independently associated with longer OS (p = 0.007 and 0.03) and PFS (p = 0.01 and 0.002, respectively). Based on these factors, 2 prognostic groups were identified for PFS (5.4 vs 3.2 months), while 3 were identified for OS (median OS of 15.2 vs 10.5 vs 5.2 months).

CONCLUSIONS

SRS is associated with longer OS and/or PFS in patients with good performance status, small-volume tumor recurrences, and heterogeneous treatment plans. The authors propose a prognostic model to identify a cohort of rGBM patients who may benefit from SRS.

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Alireza M. Mohammadi, Jason L. Schroeder, Lilyana Angelov, Samuel T. Chao, Erin S. Murphy, Jennifer S. Yu, Gennady Neyman, Xuefei Jia, John H. Suh, Gene H. Barnett, and Michael A. Vogelbaum

OBJECTIVE

The impact of the stereotactic radiosurgery (SRS) prescription dose (PD) on local progression and radiation necrosis for small (≤ 2 cm) brain metastases was evaluated.

METHODS

An institutional review board–approved retrospective review was performed on 896 patients with brain metastases ≤ 2 cm (3034 tumors) who were treated with 1229 SRS procedures between 2000 and 2012. Local progression and/or radiation necrosis were the primary end points. Each tumor was followed from the date of radiosurgery until one of the end points was reached or the last MRI follow-up. Various criteria were used to differentiate tumor progression and radiation necrosis, including the evaluation of serial MRIs, cerebral blood volume on perfusion MR, FDG-PET scans, and, in some cases, surgical pathology. The median radiographic follow-up per lesion was 6.2 months.

RESULTS

The median patient age was 56 years, and 56% of the patients were female. The most common primary pathology was non–small cell lung cancer (44%), followed by breast cancer (19%), renal cell carcinoma (14%), melanoma (11%), and small cell lung cancer (5%). The median tumor volume and median largest diameter were 0.16 cm3 and 0.8 cm, respectively. In total, 1018 lesions (34%) were larger than 1 cm in maximum diameter. The PD for 2410 tumors (80%) was 24 Gy, for 408 tumors (13%) it was 19 to 23 Gy, and for 216 tumors (7%) it was 15 to 18 Gy. In total, 87 patients (10%) had local progression of 104 tumors (3%), and 148 patients (17%) had at least radiographic evidence of radiation necrosis involving 199 tumors (7%; 4% were symptomatic). Univariate and multivariate analyses were performed for local progression and radiation necrosis. For local progression, tumors less than 1 cm (subhazard ratio [SHR] 2.32; p < 0.001), PD of 24 Gy (SHR 1.84; p = 0.01), and additional whole-brain radiation therapy (SHR 2.53; p = 0.001) were independently associated with better outcome. For the development of radiographic radiation necrosis, independent prognostic factors included size greater than 1 cm (SHR 2.13; p < 0.001), location in the corpus callosum (SHR 5.72; p < 0.001), and uncommon pathologies (SHR 1.65; p = 0.05). Size (SHR 4.78; p < 0.001) and location (SHR 7.62; p < 0.001)—but not uncommon pathologies—were independent prognostic factors for the subgroup with symptomatic radiation necrosis.

CONCLUSIONS

A PD of 24 Gy results in significantly better local control of metastases measuring < 2 cm than lower doses. In addition, tumor size is an independent prognostic factor for both local progression and radiation necrosis. Some tumor pathologies and locations may also contribute to an increased risk of radiation necrosis.

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Robert J. Weil, Gaurav G. Mavinkurve, Samuel T. Chao, Michael A. Vogelbaum, John H. Suh, Matthew Kolar, and Steven A. Toms

OBJECT

The authors assessed the feasibility of intraoperative radiotherapy (IORT) using a portable radiation source to treat newly diagnosed, surgically resected, solitary brain metastasis (BrM).

METHODS

In a nonrandomized prospective study, 23 patients with histologically confirmed BrM were treated with an Intrabeam device that delivered 14 Gy to a 2-mm depth to the resection cavity during surgery.

RESULTS

In a 5-year minimum follow-up period, progression-free survival from the time of surgery with simultaneous IORT averaged (± SD) 22 ± 33 months (range 1–96 months), with survival from the time of BrM treatment with surgery+IORT of 30 ± 32 months (range 1–96 months) and overall survival from the time of first cancer diagnosis of 71 ± 64 months (range 4–197 months). For the Graded Prognostic Assessment (GPA), patients with a score of 1.5–2.0 (n = 12) had an average posttreatment survival of 21 ± 26 months (range 1–96 months), those with a score of 2.5–3.0 (n = 7) had an average posttreatment survival of 52 ± 40 months (range 5–94 months), and those with a score of 3.5–4.0 (n = 4) had an average posttreatment survival of 17 ± 12 months (range 4–28 months). A BrM at the treatment site recurred in 7 patients 9 ± 6 months posttreatment, and 5 patients had new but distant BrM 17 ± 3 months after surgery+IORT. Six patients later received whole-brain radiation therapy, 7 patients received radiosurgery, and 2 patients received both treatments. The median Karnofsky Performance Scale scores before and 1 and 3 months after surgery were 80, 90, and 90, respectively; at the time of this writing, 3 patients remain alive with a CNS progression-free survival of > 90 months without additional BrM treatment.

CONCLUSIONS

The results of this study demonstrate the feasibility of resection combined with IORT at a dose of 14 Gy to a 2-mm peripheral margin to treat a solitary BrM. Local control, distant control, and long-term survival were comparable to those of other commonly used modalities. Surgery combined with IORT seems to be a potential adjunct to patient treatment for CNS involvement by systemic cancer.

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Rupesh Kotecha, Lilyana Angelov, Gene H. Barnett, Chandana A. Reddy, John H. Suh, Erin S. Murphy, Gennady Neyman, and Samuel T. Chao

Object

Traditionally, the treatment of choice for patients with metastases to the calvaria or skull base has been conventional radiation therapy. Because patients with systemic malignancies are also at risk for intracranial metastases, the utility of Gamma Knife surgery (GKS) for these patients has been explored to reduce excess radiation exposure to the perilesional brain parenchyma. The purpose of this study was to report the efficacy of GKS for the treatment of calvarial metastases and skull base lesions.

Methods

The authors performed a retrospective chart review of 21 patients with at least 1 calvarial or skull base metastatic lesion treated with GKS during 2001–2013. For 7 calvarial lesions, a novel technique, in which a bolus was placed over the treatment site, was used. For determination of local control or disease progression, radiation therapy data were examined and posttreatment MR images and oncology records were reviewed. Survival times from the date of procedure were estimated by using Kaplan-Meier analyses.

Results

The median patient age at treatment was 57 years (range 29–84 years). A total of 19 (90%) patients received treatment for single lesions, 1 patient received treatment for 3 lesions, and 1 patient received treatment for 4 lesions. The most common primary tumor was breast cancer (24% of patients). Per lesion, the median clinical and radiographic follow-up times were 10.3 months (range 0–71.9 months) and 7.1 months (range 0–61.3 months), respectively. Of the 26 lesions analyzed, 14 (54%) were located in calvarial bones and 12 (46%) were located in the skull base. The median lesion volume was 5.3 cm3 (range 0.3–55.6 cm3), and the median prescription margin dose was 15 Gy (range 13–24 Gy). The median overall survival time for all patients was 35.9 months, and the 1-year local control rate was 88.9% (95% CI 74.4%–100%). Local control rates did not differ between lesions treated with the bolus technique and those treated with traditional methods or between calvarial lesions and skull base lesions (p > 0.05). Of the 3 patients for whom local treatment failed, 1 patient received no further treatment and 2 patients responded to salvage chemotherapy. Subsequent brain parenchymal metastases developed in 2 patients, who then underwent GKS.

Conclusions

GKS is an effective treatment modality for patients with metastases to the calvarial bones or skull base. For patients with superficial calvarial lesions, a novel approach with bolus application resulted in excellent rates of local control. GKS provides an effective therapeutic alternative to conventional radiation therapy and should be considered for patients at risk for calvarial metastases and brain parenchymal metastases.

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Ehsan H. Balagamwala, Lilyana Angelov, Shlomo A. Koyfman, John H. Suh, Chandana A. Reddy, Toufik Djemil, Grant K. Hunter, Ping Xia, and Samuel T. Chao

Object

Stereotactic body radiotherapy (SBRT) has emerged as an important treatment option for spinal metastases from renal cell carcinoma (RCC) as a means to overcome RCC's inherent radioresistance. The authors reviewed the outcomes of SBRT for the treatment of RCC metastases to the spine at their institution, and they identified factors associated with treatment failure.

Methods

Fifty-seven patients (88 treatment sites) with RCC metastases to the spine received single-fraction SBRT. Pain relief was based on the Brief Pain Inventory and was adjusted for narcotic use according to the Radiation Therapy Oncology Group protocol 0631. Toxicity was scored according to Common Toxicity Criteria for Adverse Events version 4.0. Radiographic failure was defined as infield or adjacent (within 1 vertebral body [VB]) failure on follow-up MRI. Multivariate analyses were performed to correlate outcomes with the following variables: epidural, paraspinal, single-level, or multilevel disease (2–5 sites); neural foramen involvement; and VB fracture prior to SBRT. Kaplan-Meier analysis and Cox proportional hazards modeling were used for statistical analysis.

Results

The median follow-up and survival periods were 5.4 months (range 0.3–38 months) and 8.3 months (range 1.5–38 months), respectively. The median time to radiographic failure and unadjusted pain progression were 26.5 and 26.0 months, respectively. The median time to pain relief (from date of simulation) and duration of pain relief (from date of treatment) were 0.9 months (range 0.1–4.4 months) and 5.4 months (range 0.1–37.4 months), respectively. Multivariate analyses demonstrated that multilevel disease (hazard ratio [HR] 3.5, p = 0.02) and neural foramen involvement (HR 3.4, p = 0.02) were correlated with radiographic failure; multilevel disease (HR 2.3, p = 0.056) and VB fracture (HR 2.4, p = 0.046) were correlated with unadjusted pain progression. One patient experienced Grade 3 nausea and vomiting; no other Grade 3 or 4 toxicities were observed. Twelve treatment sites (14%) were complicated by subsequent vertebral fractures.

Conclusions

Stereotactic body radiotherapy for RCC metastases to the spine offers fast and durable pain relief with minimal toxicity. Stereotactic body radiotherapy seems optimal for patients who have solitary or few spinal metastases. Patients with neural foramen involvement are at an increased risk for failure.