Treatment outcomes of stereotactic body radiation therapy for primary and metastatic sarcoma of the spine

PURPOSE

This study evaluated the treatment outcomes of spine stereotactic body radiation therapy (SBRT) in sarcoma patients.

MATERIALS AND METHODS

A total of 44 sarcoma patients and 75 spinal lesions (6 primary tumors, 69 metastatic tumors) treated with SBRT were retrospectively reviewed between 2006 and 2017. The median radiation dose was 33 Gy (range, 18-45 Gy) in 3 fractions (range, 1-5) prescribed to the 75% isodose line.

RESULTS

The median follow-up duration was 18.2 months. The 1-year local control was 76.4%, and patients treated with single vertebral body were identified as a favorable prognostic factor on multivariate analyses. Progression-free survival at 1 year was 31.9%, with the interval between initial diagnosis and SBRT and extent of disease at the time of treatment being significant prognostic factors. The 1-year overall survival was 80.5%, and PTV and visceral metastases were independently associated with inferior overall survival.

CONCLUSION

SBRT for spinal sarcoma is effective in achieving local control, particularly when treating a single vertebral level with a limited extent of disease involvement, resulting in an excellent control rate. The extent of disease at the time of SBRT is significantly correlated with survival outcomes and should be considered when treating spine sarcoma.

A Nationwide Study of Surgery in a Newly Diagnosed Spine Metastasis Population

OBJECTIVE

The aim of this nationwide study was to analyze the current state of patients with newly diagnosed metastatic spine tumors according to surgical methods.

METHODS

Data was extracted from the Korean Health Insurance Review and Assessment Service database. Surgery was categorized into three.

METHODS

fusion, decompression, and vertebroplasty. Data included patient age, sex, health insurance type, and co-morbidities. Survival rates of metastatic spine tumor patients according to each surgical method were evaluated.

RESULTS

Among 1677 patients who had an operation, 823 patients were treated by fusion, 141 patients underwent decompression, and 713 patients were treated by vertebroplasty. The three most prevalent primary tumor sites were the lung, breast, and liver & biliary. On the other hand, the three most prevalent primary tumor sites of patients who underwent surgery were the lung, liver & biliary, and the prostate. The median survival periods for each surgical method in the metastatic spine tumor patients were 228 days for those who underwent surgery, 249 days for decompression, and 154 days for vertebroplasty. Age, sex, and comorbidities significantly affected survival rate.

CONCLUSION

For every primary tumor site, decompression was the least common surgical method during the study period. Although the three surgical methods did not significantly affect the survival period, patients with a poor prognosis tended to undergo vertebroplasty.

Nationwide comparative study of synchronous and metachronous spine metastasis in the adult Korean population

This nationwide study of the adult Korean population aimed to compare the survival period between synchronous and metachronous group and to determine recent treatment trends in newly diagnosed spine metastasis patients. Data were extracted from the Korean Health Insurance Review and Assessment Service database. Patients in this study were newly diagnosed with metastatic spine tumors between July 1, 2011 and June 31, 2014. The metachronous group was defined when the primary tumor was diagnosed prior to the diagnosis of spine metastasis, otherwise patients were considered to be the part of the synchronous group. The survival period was calculated from the date of first diagnosis of spine metastasis. In a multivariate analysis, patients in the synchronous group survived significantly longer than those in the metachronous group (P < 0.0001). Median overall survival periods were 273.6 days for the metachronous group and 541.4 days for the synchronous group. Conventional radiation therapy (RT) was the most common treatment modality for metastatic spine tumors, whereas surgery combined with RT was a steadily increasing treatment modality during the study period. Synchronous spine metastasis patients survive significantly longer than metachronous patients. Surgery combined with RT is a recently increasing trend among spine metastasis treatments.

Consensus guidelines for postoperative stereotactic body radiation therapy for spinal metastases: results of an international survey

OBJECTIVE Although postoperative stereotactic body radiation therapy (SBRT) for spinal metastases is increasingly performed, few guidelines exist for this application. The purpose of this study is to develop consensus guidelines to promote safe and effective treatment for patients with spinal metastases. METHODS Fifteen radiation oncologists and 5 neurosurgeons, representing 19 centers in 4 countries and having a collective experience of more than 1300 postoperative spine SBRT cases, completed a 19-question survey about postoperative spine SBRT practice. Responses were defined as follows: 1) consensus: selected by ≥ 75% of respondents; 2) predominant: selected by 50% of respondents or more; and 3) controversial: no single response selected by a majority of respondents. RESULTS Consensus treatment indications included: radioresistant primary, 1-2 levels of adjacent disease, and previous radiation therapy. Contraindications included: involvement of more than 3 contiguous vertebral bodies, ASIA Grade A status (complete spinal cord injury without preservation of motor or sensory function), and postoperative Bilsky Grade 3 residual (cord compression without any CSF around the cord). For treatment planning, co-registration of the preoperative MRI and postoperative T1-weighted MRI (with or without gadolinium) and delineation of the cord on the T2-weighted MRI (and/or CT myelogram in cases of significant hardware artifact) were predominant. Consensus GTV (gross tumor volume) was the postoperative residual tumor based on MRI. Predominant CTV (clinical tumor volume) practice was to include the postoperative bed defined as the entire extent of preoperative tumor, the relevant anatomical compartment and any residual disease. Consensus was achieved with respect to not including the surgical hardware and incision in the CTV. PTV (planning tumor volume) expansion was controversial, ranging from 0 to 2 mm. The spinal cord avoidance structure was predominantly the true cord. Circumferential treatment of the epidural space and margin for paraspinal extension was controversial. Prescription doses and spinal cord tolerances based on clinical scenario, neurological compromise, and prior overlapping treatments were controversial, but reasonable ranges are presented. Fifty percent of those surveyed practiced an integrated boost to areas of residual tumor and density override for hardware within the beam path. Acceptable PTV coverage was controversial, but consensus was achieved with respect to compromising coverage to meet cord constraint and fractionation to improve coverage while meeting cord constraint. CONCLUSIONS The consensus by spinal radiosurgery experts suggests that postoperative SBRT is indicated for radioresistant primary lesions, disease confined to 1-2 vertebral levels, and/or prior overlapping radiotherapy. The GTV is the postoperative residual tumor, and the CTV is the postoperative bed defined as the entire extent of preoperative tumor and anatomical compartment plus residual disease. Hardware and scar do not need to be included in CTV. While predominant agreement was reached about treatment planning and definition of organs at risk, future investigation will be critical in better understanding areas of controversy, including whether circumferential treatment of the epidural space is necessary, management of paraspinal extension, and the optimal dose fractionation schedules.

Establishment and characterization of a chordoma cell line from the tissue of a patient with dedifferentiated-type chordoma

OBJECTIVE

Chordoma is a rare bone tumor of the axial skeleton believed to originate from the remnants of the embryonic notochord. The available tumor cells are characteristically physaliferous and express brachyury, a transcription factor critical for mesoderm specification. Although chordomas are histologically not malignant, treatments remain challenging because they are resistant to radiation therapy and because wide resection is impossible in most cases. Therefore, a better understanding of the biology of chordomas using established cell lines may lead to the advancement of effective treatment strategies. The authors undertook a study to obtain this insight.

METHODS

Chordoma cells were isolated from the tissue of a patient with dedifferentiated-type chordoma (DTC) that had recurred. Cells were cultured with DMEM/F12 containing 10% fetal bovine serum and antibiotics (penicillin and streptomycin). Cell proliferation rate was measured by MTS assay. Cell-cycle distribution and cell surface expression of proteins were analyzed by fluorescence-activated cell sorting (FACS) analysis. Expression of proteins was analyzed by Western blot and immunocytochemistry. Radiation resistance was measured by clonogenic survival assay. Tumor formation was examined by injection of chordoma cells at hindlimb of nude mice.

RESULTS

The putative (DTC) cells were polygonal and did not have the conventional physaliferous characteristic seen in the U-CH1 cell line. The DTC cells exhibited similar growth rate and cell-cycle distribution, but they exhibited higher clonogenic activity in soft agar than U-CH1 cells. The DTC cells expressed high levels of platelet-derived growth factor receptor–β and a low level of brachyury and cytokeratins; they showed higher expression of stemness-related and epithelial to mesenchymal transition–related proteins than the U-CH1 cells. Intriguingly, FACS analysis revealed that DTC cells exhibited marginal surface expression of CD24 and CD44 and high surface expression of CXCR4 in comparison to U-CH1 cells. In addition, blockade of CXCR4 with its antagonist AMD3100 effectively suppressed the growth of both cell lines. The DTC cells were more resistant to paclitaxel, cisplatin, etoposide, and ionizing radiation than the U-CH1 cells. Injection of DTC cells into the hindlimb region of nude mice resulted in the efficient formation of tumors, and the histology of xenograft tumors was very similar to that of the original patient tumor.

CONCLUSIONS

The use of the established DTC cells along with preestablished cell lines of chordoma may help bring about greater understanding of the mechanisms underlying the chordoma that will lead to therapeutic strategies targeting chordomas.

The Effect of Perioperative Radiation Therapy on Spinal Bone Fusion Following Spine Tumor Surgery

Introduction

Perioperative irradiation is often combined with spine tumor surgery. Radiation is known to be detrimental to healing process of bone fusion. We tried to investigate bone fusion rate in spine tumor surgery cases with perioperative radiation therapy (RT) and to analyze significant factors affecting successful bone fusion.

Methods

Study cohort was 33 patients who underwent spinal tumor resection and bone graft surgery combined with perioperative RT. Their medical records and radiological data were analyzed retrospectively. The analyzed factors were surgical approach, location of bone graft (anterior vs. posterior), kind of graft (autologous graft vs. allograft), timing of RT (preoperative vs. postoperative), interval of RT from operation in cases of postoperative RT (within 1 month vs. after 1 month) radiation dose (above 38 Gy vs. below 38 Gy) and type of radiation therapy (conventional RT vs. stereotactic radiosurgery). The bone fusion was determined on computed tomography images.

Result

Bone fusion was identified in 19 cases (57%). The only significant factors to affect bony fusion was the kind of graft (75% in autograft vs. 41 in allograft, p=0.049). Other factors proved to be insignificant relating to postoperative bone fusion. Regarding time interval of RT and operation in cases of postoperative RT, the time interval was not significant (p=0.101).

Conclusion

Spinal fusion surgery which was combined with perioperative RT showed relatively low bone fusion rate (57%). For successful bone fusion, the selection of bone graft was the most important.

A nationwide epidemiological study of newly diagnosed spine metastasis in the adult Korean population

BACKGROUND CONTEXT

Metastatic spine tumor has become clinically important because of the availability of improved diagnostic tools and increases in survival periods in cancer patients. In spite of this interest, the burden of metastatic spine tumor on the general population has not been extensively reported.

PURPOSE

The aim of this 2009-2011 nationwide study of adult Koreans was to describe characteristics, medical use, and survival rate of patients with newly diagnosed metastatic spine tumors according to the primary tumor.

DESIGN/SETTING

This is a retrospective cohort study.

PATIENT SAMPLE

A national health insurance database was used to identify a cohort of patients with newly diagnosed metastatic spine tumors.

OUTCOME MEASURES

This study aimed to analyze characteristics, medical use, and survival rate of patients with newly diagnosed metastatic spine tumors according to the primary tumor.

METHODS

Data for patients with metastatic spine tumors were extracted from the Korean Health Insurance Review and Assessment Service database. Data included patient age, sex, health insurance type, comorbidities, medical cost, and hospital stay duration. Hospital stay duration and medical costs per person during 1 calendar year were evaluated. In addition, survival rates of patients with metastatic spine tumor according to primary tumor sites were evaluated.

RESULTS

The incidence rate of spine metastasis increased with age, year of diagnosis, and the number of comorbidities (p≤.0001). The 6 most prevalent primary tumor sites were lung, liver and biliary tract, breast, colon, stomach, and prostate. Of patients with the 6 most prevalent primary tumors, total average annual medical costs, including inpatient and outpatient services, ranged from 12,734USD (prostate origin) to 15,556 USD (lung origin). Of patients with the 6 most prevalent primary tumors, total average annual hospital stay duration, including inpatient and outpatient services, ranged from 70.8 days (stomach origin) to 78.7 days (colon origin). Median overall survival duration in patients with metastatic spine tumor was 191 days. In addition to age, sex, and comorbidities, primary tumor sites (lung, liver and biliary tract, breast, stomach, and prostate) significantly affected survival rate.

CONCLUSIONS

This nationwide study was able to depict the burden of metastatic spine tumor in Korea. The metastatic spine tumor incidence rate is highest in the group of 70- to 79-year-old men. Average annual medical costs ranged from 12,734 USD to 15,556 USD. The mean annual hospital stay duration was from 70.8 days to 78.7 days. In addition to age, sex, and comorbidities, primary tumor sites significantly affected the survival rate in patients with metastatic spine tumor.

Two Cases of Dedifferentiated Chordoma in the Sacrum

Dedifferentiated chordoma (DC) is defined as a chordoma containing sarcoma components. DC is distinguished from conventional chordoma by the rapidity of tumor growth and the potential for distant metastasis. We report two cases of DC, which are developed in the sacrum. We reviewed the medical records and imaging studies of 2 patients diagnosed with DC and the literature published. In the first case, percutaneous biopsy revealed that it was conventional chordoma in the sacrum. Patient underwent radiation therapy (RT). Six years after the RT, the tumor recurred. Surgical removal was performed and the recurrent tumor was diagnosed as DC in histopathologic examination. In the second case, a patient underwent gross total resection of sacral tumor, which was diagnosed with conventional chordoma. Aggravated tumor was detected after 4 months, and patient underwent reoperation. The second operation revealed the transformation of the tumor into DC. The survival time of the patients after the diagnosis was 10 and 31 months. Dedifferentiated chordoma is a rare and highly aggressive tumor. De novo type exists, but it usually transformed from recurrent chordoma after surgical resection or radiation.

Clinical Outcome of Treatment for Patients with Giant Cell Tumor in Spine

OBJECTIVE

The treatment of giant cell tumor (GCT) is mainly performed surgically. However, GCT in spine seems difficult to treat because of the limited surgical accessibility and proximity. In this report, we analyzed the outcome of GCT treatment in spine.

METHODS

Between 2000 and 2012, 19 patients received treatment for GCT in spine. Median age at their first diagnosis was 31 years, 10 patients were male, and 9 female. Fourteen tumors were located in the sacrum, 1 in cervical, 1 in thoracic and 3 in lumbar spine. As primary treatment, gross total removal (GTR) was done in 6 patients, and subtotal removal (STR) in 13 patients. Radiation therapy (RT) as an adjuvant therapy was performed in 2 cases in GTR group and 10 cases in STR group.

RESULTS

During the follow-up, 7 patients had local recurrence (36.8%). The average period until recurrence after primary treatment was 14 months. No recurrence was detected in GTR group. Recurrence was noted in 7 out of 13 patients who underwent STR. These differences were statistically significant (p=0.024). A median of recurrence free period (RFP) was 84 months. Also average RFP of the RT group was 112 months, and non-RT group was 65 months. These differences were statistically significant (p=0.041).

CONCLUSION

Treatment of choice for GCT in spine is a complete removal of tumor without neurological deficits. In case of incomplete removal, radiation therapy may be a useful adjuvant treatment modality.

Nationwide epidemiology and healthcare utilization of spine tumor patients in the adult Korean population, 2009-2012

Background

The aim of this nationwide study was to describe the incidence and health care utilization of adult Korean patients with primary malignant, primary nonmalignant, and metastatic spine tumors between 2009 and 2012.

Methods

Patients with primary and metastatic spine tumors were identified from the Korean Health Insurance Review and Assessment Service database between January 1, 2009, and December 31, 2012. Demographics, incidence rate, annual medical cost, and annual hospital stay of each new patient were reviewed.

Results

Of 1600 primary spine tumors diagnosed from 2009 to 2012, 373 (23.3%) were malignant, and 1227 (76.7%) were nonmalignant. The most common tumor type was neoplasm of spinal cord among primary malignant (C72.0, 51.5%) and primary nonmalignant (D33.4, 66.2%) spine tumors. Differences in primary malignant, primary nonmalignant, and metastatic spine tumor incidence by sex were significant (P = .004, <.001, and <.001, respectively). The annual incidence rate of primary nonmalignant and metastatic spine tumors increased significantly over the study period (P = .005 and <.001, respectively). Lung, liver/biliary, and breast were the most prevalent original tumor sites for metastatic spine tumors. In 2011, average annual medical costs associated with treatment of primary malignant, primary nonmalignant, and metastatic tumors were US $15 223, $6502, and $16 038, respectively. Average annual hospital stay durations for primary malignant, primary nonmalignant, and metastatic spine tumors in 2011 were 103.4, 61.7, and 79.6 days, respectively.

Conclusions

This is the first nationwide analysis of spine tumors, including metastatic spine tumors, in Asia.

Clinical significance of radiological stability in reconstructed thoracic and lumbar spine following vertebral body resection

Objective

Vertebral body replacement following corpectomy in thoracic or lumbar spine is performed with titanium mesh cage (TMC) containing any grafts. Radiological changes often occur on follow-up. This study investigated the relationship between the radiological stability and clinical symptoms.

Methods

The subjects of this study were 28 patients who underwent corpectomy on the thoracic or lumbar spine. Their medical records and radiological data were retrospectively analyzed. There were 23 cases of tumor, 2 cases of trauma, and 3 cases of infection. During operation, spinal reconstruction was done with TMC and additional screw fixation. We measured TMC settlement in sagittal plane and spinal angular change in coronal and sagittal plane at postoperative one month and last follow-up. Pain score was also checked. We investigated the correlation between radiologic change and pain status. Whether factors, such as the kind of graft material, surgical approach, and fusion can affect the radiological stability or not was analyzed as well.

Results

Mean follow-up was 23.6 months. During follow-up, 2.08±1.65° and 6.96±2.08° of angular change was observed in coronal and sagittal plane, respectively. A mean of cage settlement was 4.02±2.83 mm. Pain aggravation was observed in 4 cases. However, no significant relationship was found between spinal angular change and pain status (p=0.518, 0.458). Cage settlement was seen not to be related with pain status, either (p=0.644). No factors were found to affect the radiological stability.

Conclusion

TMC settlement and spinal angular change were often observed in reconstructed spine. However, these changes did not always cause postoperative axial pain.

Evaluation of risk factors for vertebral compression fracture after stereotactic radiosurgery in spinal tumor patients

Objective

Stereotactic radiosurgery (SRS) is an emerging treatment modality for malignant spinal tumors. After SRS, some patients suffered from pain aggravation due to development of vertebral compression fracture (VCF). In these cases, surgery should be considered.

Methods

This study consisted of 72 patients who underwent SRS due to spinal tumors. In them, whether post-SRS VCF developed or not was investigated. We retrospectively analyzed their medical records and radiological imaging data. VCF was diagnosed with X-ray and magnetic resonance imaging (MRI). The incidence, time to development and risk factors for VCF were investigated. Age, sex, whole vertebral body involvement rate, vertebral body osteolysis rate, pre-SRS spinal deformity, spinal instability neoplastic score (SINS), spinal canal encroachment, lesion level, and radiation dose were analyzed as potential risk factors. A multi-variate logistic regression model was used for statistical analysis.

Results

In our study population, VCF was observed in 26 patients (36%). The mean time to VCF development was 1.5 months. Using uni-variate analyses, the significant risk factors were pre-SRS spinal deformity, SINS, vertebral body osteolysis rate, and whole vertebral body involvement rate. However, using multi-variate analyses, the only significant risk factor was vertebral body osteolysis rate. The patients whose vertebral body was destroyed by more than 60% showed an 8.4 times higher risk of VCF than those who had vertebral body destruction of less than 60%(p=0.016).

Conclusion

The most significant prognostic factor for post-SRS VCF was vertebral body osteolysis rate, rather than whole vertebral body involvement rate. When more than 60% of the vertebral body was destroyed, the risk of VCF or spinal deformity was high.

Stereotactic radiosurgery compared with external radiation therapy as a primary treatment in spine metastasis from renal cell carcinoma: a multicenter, matched-pair study

The aim of this multicenter, matched- pair study was to compare the outcome of stereotactic radiosurgery (SRS) with that of external radiation therapy (RT) when used as a primary treatment in spine metastasis from renal cell carcinoma (RCC). From 2005 to 2012, 13 patients underwent SRS as a primary treatment in spine metastasis from RCC. Thirteen patients who underwent RT as the primary treatment of RCC spine metastasis were paired with the SRS patients based on age, number of spine metastasis, time interval from original tumor diagnosis to spine metastasis, Eastern Cooperative Oncology Group status, and year of treatment. The primary outcomes of interest were pain relief and progression free survival. Secondary outcomes were treatment toxicities and need for further treatment. The perioperative VAS score decrease was larger in the SRS group than that in the RT group (P = 0.04). More SRS patients had complete or partial pain relief although the difference was not significant. There was a significant difference in progression free survival between the two groups (P = 0.01). The percentage of patients with toxicities was 38.5 % (5/13) in the SRS group and 53.9 % (7/13) in the RT group, but the difference was not significant. There were 2 SRS patients and 3 RT patients who received further intervention at the index segment. This study showed that, when performed as a primary treatment in spine metastasis from RCC, SRS provides relatively better pain relief and better local control than that obtained from RT.

Stereotactic radiosurgery for spinal neoplasms: current status and future perspective

Stereotactic radiosurgery (SRS) is increasingly utilized for the treatment of primary and metastatic spinal tumors. SRS implies high dose per fraction radiation (typically >5 Gy per fraction) is delivered to an image-guided target in 1 to 5 fractions by using conformal radiation techniques. Its use is based on the radiobiological superiority of hypofractionated high dose radiation and precision of radiation delivery using real time image-guidance facilities. Spine SRS devices can be classified into two groups according to the type of treatment unit: Cyberknife (Accuray, Inc., Sunnyvale, CA, USA) and multileaf collimation (MLC) linear accelerator (LINAC) systems. The major indications for the use of SRS include primary and metastatic spine tumors. In spine metastasis, SRS was reported to be highly effective at decreasing pain, regardless of prior radiation, with an overall pain improvement rate of 85% and local control rate of approximately 90%. Improved local control could lead to more effective palliation and potentially longer survival. Some of benign spinal disease such as schwannoma, neurofibroma, meningioma, hemangioblastoma and vascular malformations were also treated. Complications associated with spinal SRS have been rarely reported, myelopathy risk is estimated to be 0.4% of treated patients. We believe that SRS is an established treatment for patients with spinal tumors, which is both safe and highly effective. The purpose of this review is to introduce principles of spinal SRS and summarize the literature regarding the usefulness of SRS for treatment of spinal neoplasms.

Survival and recurrence rate after treatment for primary spinal sarcomas

Objective

We have limited understanding on the presentation and survival of primary spinal sarcomas. The survival, recurrence rate, and related prognostic factors were investigated after treatment for primary sarcomas of the spine.

Methods

Retrospective analysis of medical records and radiological data was done for 29 patients in whom treatment was performed due to primary sarcoma of the spine from 2000 to 2010. As for treatment method, non-radical operation, radiation therapy, and chemotherapy were simultaneously or sequentially combined. Overall survival (OS), progression free survival (PFS), ambulatory function, and pain status were analyzed. In addition, factors affecting survival and recurrence were analyzed : age (≤42 or ≥43), gender, tumor histologic type, lesion location (mobile spine or rigid spine), weakness at diagnosis, pain at diagnosis, ambulation at diagnosis, initial treatment, radiation therapy, kind of irradiation, surgery, chemotherapy and distant metastasis.

Results

Median OS was 60 months, the recurrence rate was 79.3% and median PFS was 26 months. Patients with distant metastasis showed significantly shorter survival than those without metastasis. No factors were found to be significant relating to recurrence. Prognostic factor associated with walking ability was the presence of weakness at diagnosis.

Conclusion

Primary spinal sarcomas are difficult to cure and show high recurrence rate. However, the development of new treatment methods is improving survival.

Local tumor control after retreatment of spinal metastasis using stereotactic body radiotherapy; comparison with initial treatment group

BACKGROUND

The aim of this study is to evaluate local control rates after stereotactic body radiotherapy (SBRT) in recurrent spinal metastasis after external beam radiotherapy (EBRT) and new spinal metastatic lesions.

MATERIAL AND METHODS

Retrospective review of medical records and radiological data was performed on 54 retreatment and 131 initial SBRT patients. To compare various fractionation schedules, the biologically effective dose (BED) was applied. SBRT dose was calculated with linear-quadratic model and normalized to a 2-Gy equivalent dose (nBED, α/β =2 Gy for spinal cord, α/β =10 Gy for tumor). Doses to a point within the spinal cord that received the maximum dose (Pmax) were checked. Local control failure was defined as progression by imaging study. Overall survival, progression free survival, delivered radiation dose to tumor and spinal cord, and spinal cord Pmax nBED were compared in two groups.

RESULTS

The mean delivered radiation doses to tumor margin during SBRT were 51.1 Gy2/10 (retreatment) and 50.7 Gy2/10 (initial treatment). Mean survival was 29.6 months (overall)/20.7 months (retreatment)/ 32.4 months (initial treatment). Mean progression free period was 23.9 months (overall)/18.0 months (retreatment)/ 26.0 months (initial treatment). Radiological control rates of retreatment and initial treatment group were 96%/95% at six months, 81%/89% at 12 months and 79%/90% at 24 months. Among 54 retreatment lesions, 13 lesions showed local control failure during follow-up. With regard to spinal cord radiation dose during SBRT, Spinal cord Pmax nBED was 46.2 Gy2/2 (retreatment) and 48.7 Gy2/2 (initial treatment). In retreatment group, total nBED to spinal cord was a mean of 83.4 Gy2/2. There was no case of radiation myelopathy detected.

CONCLUSIONS

Retreatment of spinal metastases using SBRT provided effective local control without neurological complications.

Analysis of prognostic factors relating to postoperative survival in spinal metastases

Objective

To analyze the prognostic factors thought to be related with survival time after a spinal metastasis operation.

Methods

We retrospectively analyzed 217 patients who underwent spinal metastasis operations in our hospital from 2001 to 2009. Hematological malignancies, such as multiple myeloma and lymphoma, were excluded. The factors thought to be related with postoperative survival time were gender, age (below 55, above 56), primary tumor growth rate (slow, moderate, rapid group), spinal location (cervical, thoracic, and lumbo-sacral spine), the timing of radiation therapy (preoperative, postoperative, no radiation), operation type (decompressive laminectomy with or without posterior fixation, corpectomy with anterior fusion, corpectomy with posterior fixation), preoperative systemic condition (below 5 points, above 6 points classified by Tomita scoring), pre- and postoperative ambulatory function (ambulatory, non-ambulatory), number of spinal metastases (single, multiple), time to spinal metastasis from the primary cancer diagnosis (below 21 months, above 22 months), and postoperative complication.

Results

The study cohort mean age at the time of surgery was 55.5 years. The median survival time after spinal operation and spinal metastasis diagnosis were 6.0 and 9.0 months. In univariate analysis, factors such as gender, primary tumor growth rate, preoperative systemic condition, and preoperative and postoperative ambulatory status were shown to be related to postoperative survival. In multivariate analysis, statistically significant factors were preoperative systemic condition (p=0.048) and postoperative ambulatory status (p<0.001). The other factors had no statistical significance.

Conclusion

The factors predictive for postoperative survival time should be considered in the surgery of spinal metastasis patients.

Anterior construct location following vertebral body metastasis reconstruction through a posterolateral transpedicular approach: does it matter?

Object

The posterolateral transpedicular approach (PTA) is a widely used method for the surgical treatment of vertebral body metastases. It is crucial to understand the optimal location of the anterior graft in terms of sound and durable reconstruction following PTA. The purpose of this study was to investigate whether postoperative construct stability is related to the location of anterior grafts.

Methods

The authors conducted a retrospective review of 45 cases of metastatic spine disease with epidural tumor extension in which patients underwent circumferential decompression and fusion by means of PTA. Mechanical (anterior construct stability), pain (visual analog scale score), and neurological (American Spinal Injury Association scale) outcomes were evaluated and correlated with the anterior graft location (lateral or central) and surgical approach (unilateral or bilateral), number of decompressed levels, types of anterior graft, screw density of posterior fixation (number of screws used divided by the number of pedicles spanned), and kyphotic angle change from the immediate postoperative period to the most recent follow-up.

Results

Seven of 45 constructs were judged unstable—5 with a lateral location of the anterior graft and 2 with a central location.

The anterior graft was located laterally in 31 cases (69%), centrally in 11 (24%), and bilaterally in 3 (7%). A unilateral approach was used in 33 cases and a bilateral approach in 12. Neither the location of the anterior graft nor the approach had a significant effect on the stability of the reconstructed spine (p > 0.05). There was a significant difference in construct stability between the single-level decompression group (33 patients) and the multiple-level decompression group (12 patients) (p = 0.0001). The types of anterior graft, screw density, and kyphotic angle change were not correlated to the mechanical outcome.

Conclusions

The anterior graft location showed no significant relationship to the final mechanical, pain, and neurological outcomes.

The treatment outcome depending on the extent of resection in skull base and spinal chordomas

PURPOSE

The authors tried to assess the treatment outcomes depending on the extent of resection in axial chordomas and compare the outcome of two adjunctive therapies (external beam radiation therapy vs. stereotactic radiosurgery) following incomplete tumour resection in terms of local tumour control.

PATIENTS AND METHODS

We retrospectively reviewed 30 consecutive patients with chordoma involving skull base, sacrum and mobile spine between 1993 and 2008. Their initial treatments had different extent of resection. Wide resection was performed for 12 (40%), subtotal resection and adjunctive radiotherapy/radiosurgery for 12 (40%), while six patients (20%) were solely treated with radiotherapy/radiosurgery. For these three groups, overall and progression-free survival rate were compared.

RESULTS

The overall survival rate was 96% at 5 years and 67% at 10 years. Tumour progression-free survival (PFS) rates were 73% and 43% at 5 and 10 years, respectively. Local tumour progression was seen in 67% in all patients, 58% in wide resection group, 67% in subtotal resection plus radiotherapy/radiosurgery group, and 75% in radiotherapy/radiosurgery group; however, this was not statistically significant (P = 0.69). Neither the extent of resection nor tumour location significantly influenced overall and progression-free survival (P > 0.05). With regard to the type of radiotherapy, tumour progression occurred in all lesions treated with external photon beam radiation therapy (EBRT) but only 38% of lesions treated with stereotactic radiosurgery (SRS) (P = 0.003).

CONCLUSIONS

Adjunctive radiotherapy/radiosurgery following subtotal resection showed comparable local control and survival to wide resection. SRS offered superior local tumour control compared to EBRT.

Comparison of MR imaging and FDG-PET/CT in the differential diagnosis of benign and malignant vertebral compression fractures

OBJECT

Differentiation between malignant and benign vertebral compression fractures (VCFs) is important but sometimes difficult, especially in elderly cancer patients. The authors investigated the findings of MR imaging and FDG-PET/CT for the differentiation of VCFs.

METHODS

Between 2007 and 2008, the authors evaluated and treated 102 VCFs in 96 patients. The final diagnosis, based on biopsy results or clinical follow-up, was benign fracture in 67 lesions in 65 patients and malignant fracture in 35 lesions in 31 patients. Magnetic resonance images were obtained in all patients, and FDG-PET/CT was performed in 17 patients in the benign fracture group and 20 in the malignant fracture group. The prevalence of 3 significant MR imaging findings (posterior cortical bulging, epidural mass formation, and pedicle enhancement) and the presence of radiotracer uptake on FDG-PET/CT were evaluated in the 2 groups. The maximum standardized uptake value (SUV(max)) on FDG-PET/CT was compared between the 2 groups, and diagnostic threshold value was sought to confirm malignancy. The diagnostic accuracy of MR imaging and FDG-PET/CT was compared in the differentiation of malignant from benign VCFs.

RESULTS

Posterior cortical bulging was seen in 26 (74%) of 35 malignant lesions and 30 (45%) of 67 benign ones, epidural mass formation in 27 (77%) of the malignant lesions and 25% of the benign ones, and pedicle enhancement in 30 (91%) of the 33 malignant lesions and 18 (39%) of the 46 benign ones evaluated with Gd-enhanced MR imaging. These differences were statistically significant for each feature. Sensitivity and specificity for predicting malignancy were, respectively, 74% and 55% for posterior cortical bulging, 77% and 74% for epidural mass formation, and 90% and 61% for pedicle enhancement. Simultaneous occurrence of 3 significant features was found in 21 (64%) of the 33 malignant and 8 (17%) of the 46 benign lesions for which complete MR imaging data were available and showed sensitivity of 64% and specificity of 83%. The presence of radiotracer uptake on FDG-PET/CT was seen in all 20 (100%) of the 20 malignant lesions and 12 (71%) 17 of the benign lesions evaluated by FDG-PET/CT and showed a sensitivity of 100% and specificity of 29%. There was a significant difference in mean (± SD) SUV(max) for the malignant (6.29 ± 3.50) and benign (2.38 ± 1.90) lesions (p < 0.001). The most reliable threshold for SUV(max) was found to be 4.25, which yielded a sensitivity of 85% and a specificity of 71%.

CONCLUSIONS

When MR imaging findings are equivocal, FDG-PET/CT can be considered as an adjunctive diagnostic method for differentiating malignant from benign VCFs. In comparison with MR imaging, FDG-PET/CT showed slightly higher sensitivity and lower specificity.

The use of pedicle screw-rod system for the posterior fixation in cervico-thoracic junction

OBJECTIVE

In cervico-thoracic junction (CTJ), the use of strong fixation device such as pedicle screw-rod system is often required. Purpose of this study is to analyze the anatomical features of C7 and T1 pedicles related to screw insertion and to evaluate the safety of pedicle screw insertion at these levels.

METHODS

Nineteen patients underwent posterior CTJ fixation with C7 and/or T1 included in fixation levels. Seventeen patients had tumorous conditions and two with post-laminectomy kyphosis. The anatomical features were analyzed for C7 and T1 pedicles in 19 patients using computerized tomography (CT). Pedicle screw and rod fixation system was used in 16 patients. Pedicle violation by screws was evaluated with postoperative CT scan.

RESULTS

The mean values of the width, height, stable depth, safety angle, transverse angle, and sagittal angle of C7 pedicles were 6.9 +/- 1.34 mm, 8.23 +/- 1.18 mm, 30.93 +/- 4.65 mm, 26.42 +/- 7.91 degrees, 25.9 +/- 4.83 degrees, and 10.6 +/- 3.39 degrees. At T1 pedicles, anatomic parameters were similar to those of C7. The pedicle violation revealed that 64.1% showed grade I violation and 35.9% showed grade II violation, overall. As for C7 pedicle screw insertion, grade I was 61.5% and grade II 38.5%. At T1 level, grade I was 65.0% and grade II 35.0%. There was no significant difference in violation rate between the whole group, C7, and T1 group.

CONCLUSION

C7 pedicles can withstand pedicle screw insertion. C7 pedicle and T1 pedicle are anatomically very similar. With the use of adequate fluoroscopic oblique view, pedicle screw can be safely inserted at C7 and T1 levels.

Clinical results of cyberknife(r) radiosurgery for spinal metastases

OBJECTIVE

Primary treatment of spinal metastasis has been external beam radiotherapy. Recent advance of technology enables radiosurgery to be extended to extracranial lesions. The purpose of this study was to determine the clinical effectiveness and safety of stereotactic radiosurgery using Cyberknife in spinal metastasis.

METHODS

From June, 2002 to December, 2007, 129 patients with 167 spinal metastases were treated with Cyberknife. Most of the patients (94%) presented with pain and nine patients suffered from motor deficits. Twelve patients were asymptomatic. Fifty-three patients (32%) had previous radiation therapy. Using Cyberknife, 16-39 Gy in 1-5 fractions were delivered to spinal metastatic lesions. Radiation dose was not different regarding the tumor pathology or tumor volume.

RESULTS

After six months follow-up, patient evaluation was possible in 108 lesions. Among them, significant pain relief was seen in 98 lesions (91%). Radiological data were obtained in 83 lesions. The mass size was decreased or stable in 75 lesions and increased in eight lesions. Radiological control failure cases were hepatocellular carcinoma (5 cases), lung cancer (1 case), breast cancer (1 case) and renal cell carcinoma (1 case). Treatment-related radiation injury was not detected.

CONCLUSION

Cyberknife radiosurgery is clinically effective and safe for spinal metastases. It is true even in previously irradiated patients. Compared to conventional radiation therapy, Cyberknife shows higher pain control rate and its treatment process is more convenient for patients. Thus, it can be regarded as a primary treatment modality for spinal metastases.

The Changes in Range of Motion after a Lumbar Spinal Arthroplasty with Charité in the Human Cadaveric Spine under Physiologic Compressive Follower Preload : A Comparative Study between Load Control Protocol and Hybrid Protocol

OBJECTIVE

To compare two testing protocols for evaluating range of motion (ROM) changes in the preloaded cadaveric spines implanted with a mobile core type Charité lumbar artificial disc.

METHODS

Using five human cadaveric lumbosacral spines (L2-S2), baseline ROMs were measured with a bending moment of 8 Nm for all motion modes (flexion/extension, lateral bending, and axial rotation) in intact spine. The ROM was tracked using a video-based motion-capturing system. After the Charité disc was implanted at the L4-L5 level, the measurement was repeated using two different methods : 1) loading up to 8 Nm with the compressive follower preload as in testing the intact spine (Load control protocol), 2) loading in displacement control until the total ROM of L2-S2 matches that when the intact spine was loaded under load control (Hybrid protocol). The comparison between the data of each protocol was performed.

RESULTS

The ROMs of the L4-L5 arthroplasty level were increased in all test modalities (p < 0.05 in bending and rotation) under both load and hybrid protocols. At the adjacent segments, the ROMs were increased in all modes except flexion under load control protocol. Under hybrid protocol, the adjacent segments demonstrated decreased ROMs in all modalities except extension at the inferior segment. Statistical significance between load and hybrid protocols was observed during bending and rotation at the operative and adjacent levels (p < 0.05).

CONCLUSION

In hybrid protocol, the Charité disc provided a relatively better restoration of ROM, than in the load control protocol, reproducing clinical observations in terms of motion following surgery.

Clinical outcomes after percutaneous vertebroplasty for pathologic compression fractures in osteolytic metastatic spinal disease

OBJECTIVE

Percutaneous vertebroplasty (VP) can provide immediate stabilization in pathologic fractures of spinal tumors. However, long term follow-up data in cases of pathologic fractures are lacking. The authors report follow-up results of VP in 185 pathologic fractures of 102 spinal tumor patients.

METHODS

Percutaneous VP was performed at 185 vertebral bodies of 102 patients from 2001 to 2007. Retrospective analysis was done with medical records and radiological data. The change of visual analogue score (VAS), vertebral body (VB) height and kyphotic angle were measured preoperatively and on postoperative one day and at 3, 6, and 12 months.

RESULTS

The patients were composed of metastatic spine tumors (81%) and multiple myeloma (19%). Involved spinal segments were between T6 and L5. Mean follow-up period was 12.2 months. VAS for back pain was 8.24 preoperatively, 3.59 (postoperative one day), 4.08 (three months) and 5.22 (one year). VB compression ratio changed from 21.33% preoperatively to 13.82% (postoperative one day), 14.36% (three month), and 16.04% (one year). Kyphotic angle changed from 15.35 degrees preoperatively to 12.03 degrees (postoperative one day), 13.64 degrees (three month), and 15.61 degrees (one year).

CONCLUSION

Immediate pain relief was definite after VP in pathologic compression fracture of osteolytic spinal disease. Although VAS was slightly increased on one year follow-up, VP effect was maintained without significant change. These results indicate that VP could be a safe and effective procedure as a palliative treatment of the spinal tumor patients.

Changes in adjacent-level disc pressure and facet joint force after cervical arthroplasty compared with cervical discectomy and fusion

OBJECT

The authors of previous in vitro investigations have reported an increase in adjacent-level intradiscal pressures (IDPs) and facet joint stresses following cervical spine fusion. This study was performed to compare adjacent-level IDPs and facet force following arthroplasty with the fusion model.

METHODS

Eighteen human cadaveric cervical spines were tested in the intact state for different modes of motion (extension, flexion, bending, and rotation) up to 2 Nm. The specimens were then divided into three groups: those involving the ProDisc-C cervical artificial disc, Prestige cervical artificial disc, and cervical fusion. They were load tested after application of instrumentation or surgery at the C6-7 level. During the test, IDPs and facet forces were measured at adjacent levels.

RESULTS

In arthroplasty-treated specimens, the IDP showed little difference from that of the intact spine at both proximal and distal levels. In fusion-treated specimens, the IDP increased at the posterior anulus fibrosus on extension and at the anterior anulus fibrosus on flexion at the proximal level. At the distal level, the IDP change was not significant. The facet force changes were minimal in flexion, bending, and rotation modes in both arthroplasty- and fusion-treated spines. Significant changes were noted in the extension mode only. In extension, arthroplasty models exhibited significant increases of facet force at the treated level. In the fusion model the facet forces decreased at the treated segment and increased at the adjacent segment.

CONCLUSIONS

The two artificial discs of the semiconstrained systems maintain adjacent-level IDPs near the preoperative values in all modes of motion, but with respect to facet force pressure tended to increase after arthroplasty.

Range of motion change after cervical arthroplasty with ProDisc-C and prestige artificial discs compared with anterior cervical discectomy and fusion

OBJECT

Range of motion (ROM) changes were evaluated at the surgically treated and adjacent segments in cadaveric specimens treated with two different cervical artificial discs compared with those measured in intact spine and fusion models.

METHODS

Eighteen cadaveric human cervical spines were tested in the intact state for the different modes of motion (extension, flexion, lateral bending, and axial rotation) up to 2 Nm. Three groups of specimens (fitted with either the ProDisc-C or Prestige II cervical artificial disc or submitted to anterior cervical discectomy and fusion [ACDF]) were tested after implantation at C6-7 level. The ROM values were measured at treated and adjacent segments, and these values were then compared with those measured in the intact spine.

RESULTS

At the surgically treated segment, the ROM increased after arthroplasty compared with the intact spine in extension (54% in the ProDisc-C group, 47% in the Prestige group) and in flexion (27% in the ProDisc-C group, 10% in the Prestige group). In bending and rotation, the postarthroplasty ROMs were greater than those of the intact spine (10% in the ProDisc-C group and 55% in the Prestige group in bending, 17% in the ProDisc-C group and 50% in the Prestige group in rotation). At the adjacent levels the ROMs decreased in all specimens treated with either artificial disc in all modes of motion (< 10%) except for extension at the inferior the level (29% decrease for ProDisc-C implant, 12% decrease for Prestige disc). The ROM for all motion modes in the ACDF-treated spine decreased at the treated level (range 18-44%) but increased at the adjacent levels (range 3-20%).

CONCLUSIONS

Both ProDisc-C and Prestige artificial discs were associated with increased ROM at the surgically treated segment compared with the intact spine with or without significance for all modes of testing. In addition, adjacent-level ROM decreased in all modes of motion except extension in specimens fitted with both artificial discs.

Biomechanical study of thoracolumbar junction fixation devices with different diameter dual-rod systems

OBJECT

Advances in the design of a smaller-diameter rod system for use in the thoracolumbar region prompted the authors to undertake this biomechanical study of two different thoracolumbar implants.

METHODS

In vitro biomechanical testing was performed using human cadaveric spines. All specimens were loaded to a maximum moment of 5 Nm with 300-N axial preload in six modes of motion. Two types of anterior implants with different rod diameters were applied to intact T10-12 specimens in two groups. The loading was repeated and the range of motion (ROM) was measured. A T-11 corpectomy was then performed and a strain gauge-mounted carbon fiber stackable cage was implanted. The ROM and compression force on the cage were measured, and the mean values were compared between these two groups. With stabilization of the intact spine, ROM decreased least in extension and greatest in bending compared with the intact specimens. After corpectomy and stabilization, ROM increased in extension by 104.89 +/- 53.09% in specimens with a 6.35-mm rod insertion and by 83.81 +/- 16.96% in those with a 5.5-mm rod, respectively; in flexion, ROM decreased by 26.98 +/- 27.43% (6.35 mm) and by 9.59 +/- 15.42% (5.5 mm), respectively; and in bending and rotation, both groups each showed a decrease in ROM. The load sharing of the cage was similar between the two groups (the 6.35-mm compared with 5.5-mm rods): 47.44 and 44.73% (neutral), 49.16 and 39.02% (extension), 61.90 and 56.88% (flexion), respectively.

CONCLUSIONS

There were no statistical differences in the ROM and load sharing of the cage when either the 6.35-or 5.5-mm-diameter dual-rod was used.

Surgical treatment for thoracic spinal stenosis

OBJECTIVES

To describe the underlying causes, surgical results and prognostic factors in thoracic stenosis causing myelopathy.

METHODS

The underlying causes and surgical results were analyzed retrospectively in 28 cases of thoracic spinal stenosis which caused myelopathy. Degenerative spondylosis was the most common cause, and three cases were associated with systemic diseases. Decompressive laminectomy was performed in 24 cases, anterior decompression in five cases, and combined decompression in one case. Ossification of ligamentum flavum was found in 18 cases, facet hypertrophy in 13, ossification of posterior longitudinal ligament in six, and ventral spur in four. Postoperatively 16 patients improved and four patients worsened. Follow-up ranged from 2 months to 5 years and 8 months). Statistical analysis was performed using a chi(2) test to investigate the relationship between subjects. Multivariant analysis (general linear model) was used to determine the factors which influence surgical outcome.

RESULTS

There were neurological improvements in 16 patients, in whom Nurick grade changed from 3.3 preoperatively to 1.8 postoperatively. Eight patients showed no significant change in functional grade and four patients deteriorated after decompressive laminectomy. The group of which initial symptom duration was less than 2 years showed better results (P=0.006). The group with sufficient decompression and no additional proximal stenosis had better treatment outcome (P=0.005, P=0.002).

CONCLUSION

Chronic severe myelopathy caused by thoracic spinal stenosis can be reversible with appropriate decompression. Surgical outcome was dependent on initial symptom duration, sufficient decompression and presence of additional proximal stenosis.

SPONSORSHIP

This study was supported by a grant No. 02-1997-071-0 from the Seoul National University Hospital Research Fund.