The effect of radiotherapy, chemotherapy, and immunotherapy on fusion rate in spinal surgery using osteobiologics for patients with metastatic spinal disease: a systematic review.

OBJECTIVE: To evaluate the impact that adjuvant therapies like radiotherapy, chemotherapy, and immunotherapy have on osteobiologic properties and bony regeneration in patients with metastatic spine disease (MSD) undergoing spinal fusion surgery. METHODS: PubMed and ClinicalTrials.gov searches were performed. MSD patients undergoing fusion surgery with an osteobiologic and radiotherapy, chemotherapy and/or immunotherapy were included. Demographics, primary tumor, surgery, adjuvant treatments, osteobiologic type, fusion rates with scoring criteria, hardware failure, reoperation rates, follow-up, and survival were extracted. 1487 studies were screened, 20 included. RESULTS: 585 patients (464 with MSD) had fusion rates ranging from 17.9 to 100%. In the setting of radiotherapy, fusion rates of 10 studies using autologous bone graft (autograft), 5 studies using allogenic bone graft (allograft), 5 studies using combination autograft/allograft, 4 studies using biomaterial scaffolds (BMS), 3 studies using demineralized bone matrices (DBM), and 1 study using growth factors (GF), were 50-100%, 17.9-100%, 57.8-100%, 52.9-100%, 20-100%, and 100%, respectively. A higher incidence of fusion in patients with autograft or allograft receiving stereotactic body radiotherapy (SBRT) at lower biologically effective doses (BED) and at least 1-month postoperatively was noted. Chemotherapy had no impact on fusion. No studies evaluated the impact of immunotherapy on fusion. CONCLUSIONS: SBRT at lower doses given greater than 1-month postoperatively may enhance bony fusion in patients receiving autograft, allograft, or autograft/allograft. Chemotherapy may delay bony fusion without affecting overall fusion rates. Preclinical studies suggest immunotherapy may prevent osteolysis and promote osteogenesis, but no studies have yet evaluated the clinical impact of these findings on spinal fusion. Further research is needed on osteobiologics in bony regeneration in the MSD population.

Epidemiology, tumour characteristics, treatment and outcomes associated with spinal nerve sheath tumours: a systematic review protocol.

INTRODUCTION: Nerve sheath tumours arise from both the central and peripheral nervous systems. In particular, cases of spinal or paraspinal origins are scarce and poorly covered in the literature. This systematic review aims to summarise the body of evidence regarding spinal nerve sheath tumours and assess its quality, to provide the current knowledge on epidemiology, tumour characteristics, diagnostics, treatment strategies and outcomes. METHODS AND ANALYSIS: Databases including PubMed, Web of Science and Embase will be searched using keywords such as "spinal", "nerve sheath", "neurofibroma", "schwannoma", "neurinoma" and "neurilemoma". The search will be limited to studies published no earlier than 2000 without language restrictions. Case reports, editorials, letters and reviews will be excluded. Reference lists of identified studies will be searched to find possible additional relevant records. Identified studies will be screened for inclusion, by one reviewer at first and then two independent ones in the next step to increase the external validity. The Rayyan platform will be used for the screening and inclusion process. Data extraction within several predetermined areas of interest will proceed. Subjects of interest include epidemiology, histopathology, radiological diagnostics, surgery, complications, non-surgical treatment alternatives, disease outcomes and predictors of outcome, and recurrence rates. On satisfactory amount of homogenous data, a meta-analysis of key outcomes such as recurrence risk or postoperative neurological improvement will be performed. This systematic review will primarily serve as a reference guide to aid in diagnosis and treatment of patients with spinal schwannomas, while also spotlighting the knowledge gaps in the literature to help guide future research initiatives. ETHICS AND DISSEMINATION: Ethics approval is not required for the protocol or review as both are based on existing publications. For dissemination, the final manuscript will be submitted to a peer-reviewed journal.

Global trends in the utilisation of NOMS framework for spinal metastasis management: A systematic review.

INTRODUCTION: Traditional risk stratification systems based on the clinicopathological criteria have limitations and may not accurately predict outcomes for all patients. The neurologic, oncologic, mechanical, and systemic (NOMS) framework aims to optimise treatment outcomes and improve patient care. Here, we aimed to provide a comprehensive overview of the NOMS framework within the context of spinal metastasis. MATERIALS AND METHODS: The study rigorously followed the guidelines set by PRISMA. We conducted an extensive search and be as transparent as possible across wellregarded databases such as PubMed and Euro PMC. The primary outcome measure focused on examining the feasibility of implementing the NOMS framework for patients with spinal metastasis in real-world clinical settings, and this measure was predefined and justified. RESULTS: This systematic review included three studies involving 300 participants with spinal metastases at the cervicothoracic junction. The studies examined surgical interventions like decompression, fusion and corpectomy within the NOMS framework. Across the studies, the NOMS approach is consistently associated with adverse outcomes, including complication rates, surgical revisions, hardware complications, deformities, tumour recurrence and variable survival rates. It is also linked to hospital stays, ICU durations and specific discharge statuses. Another study focused on spinal metastasis patients undergoing endoscopic surgery, highlighting the NOMS framework's connection to recurrence rates, performance metrics, neurological status, pain management, functional recovery and quality of life. In addition, other studies explored navigated instrumentation, with a primary focus on screw placement accuracy. All three studies demonstrated methodological rigor by reporting adequate allocation concealment. CONCLUSION: NOMS framework consistently associates with adverse spinal metastasis surgery outcomes.

Tailored surgical approaches for spinal chordomas: A multidisciplinary perspective.

INTRODUCTION: The treatment of spinal chordomas presents a significant challenge due to their resistance to both radiotherapy and chemotherapy as well as the complexity of the surgical procedures required. This study presents a series of cases of primary spinal chordomas, focusing on the development of a personalized therapeutic strategy that is tailored to each patient's unique clinical status. This approach aims to ensure that treatments are optimally aligned with the patient's overall prognosis and surgical eligibility. METHODS: This retrospective study analyzed 14 patients with primary spinal chordomas treated at our institution. We evaluated surgical strategies, clinical outcomes, and survival rates, The therapeutic strategy was formulated after interdisciplinary conferences with sarcoma management specialists. Data were collected on patient demographics, surgical details, postoperative outcomes, and follow-up status. RESULTS: All patients presented with neurological deficits preoperatively, which generally improved post-surgery. The study included a detailed analysis of two distinct surgical approaches: five patients underwent en bloc resection with dorsal stabilization and nine received decompression only. Patients undergoing en bloc resection showed a reduced need for additional surgery due to the comprehensive removal of the tumor. As anticipated, 40% of the patients who underwent decompression experienced tumor progression within the first three months. However, given the poor overall prognosis, the objective of maintaining neurological function was achieved. CONCLUSIONS: Surgical en bloc resection offers a viable and effective intervention for spinal chordomas, enhancing neurological function. It is imperative to tailor treatment strategies to individual prognoses, integrating insights from multidisciplinary discussions that meticulously evaluate surgical risks. This collaborative approach aids in selecting the most appropriate surgical technique tailored to each patient's specific condition.

Spinal chordoma and chondrosarcoma treatment experiences - a 20-year retrospective study from databases of two medical centers.

The research retrospectively analyzed cases of spinal chordoma and chondrosarcoma involving patients who received treatment at the two hospitals between 2001 and 2023. Among the 48 patients studied (39 chordoma and 9 chondrosarcoma cases), the average age was 53.9 ± 15.8 years, with a range of 17 to 86 years. Out of these patients, 43 underwent excision surgery and were categorized based on tumor margin into negative (R0) or microscopically positive (R1) margin (n = 14) and macroscopically positive (R2) margin (n = 29) groups. The mean overall survival (OS) for R0/R1 and R2 groups was 156.5 ± 19.3 and 79.2 ± 11.9 months, respectively (p value = 0.012). The mean progression-free survival (PFS) for R0/R1 and R2 was 112.9 ± 24.4 and 25.5 ± 5.5 months (p value < 0.001). The study showed that regardless of whether patients in the R0/R1 or R2 groups received radiation therapy (RT) or not, there was no significant improvement in OS or PFS. Specifically, the OS and PFS for the RT only group were 75.9 ± 16.6 and 73.3 ± 18.0 months. In conclusion, the recommended treatment approach for spinal chordoma and chondrosarcoma remains en bloc resection surgery with an appropriate margin. Patients who are unsuitable for or decline surgery may find a beneficial disease control rate with traditional external beam photon/proton therapy.

Augmented Reality Navigation System (SIRIO) for Neuroprotection in Vertebral Tumoral Ablation.

(1) This study evaluates the impact of the CT-guided SIRIO augmented reality navigation system on the procedural efficacy and clinical outcomes of neuroprotection in vertebral thermal ablation (RTA) for primary and metastatic bone tumors. (2) Methods: A retrospective non-randomized analysis of 28 vertebral RTA procedures was conducted, comparing 12 SIRIO-assisted and 16 non-SIRIO-assisted procedures. The primary outcomes included dose-length product (DLP) and epidural dissection time. The secondary outcomes included technical success, complication rates, and pain scores at procedural time (VAS Time 0) and three months post-procedure (VAS Time 1). The statistical analyses included t-tests, Mann-Whitney U tests, and multiple regression. (3) Results: SIRIO-assisted procedures significantly reduced DLP (307.42 mGycm vs. 460.31 mGycm, p = 2.23 × 10-8) and procedural epidural dissection time (13.48 min vs. 32.26 min, p = 2.61 × 10-12) compared to non-SIRIO-assisted procedures. Multiple regression confirmed these reductions were significant (DLP: ß = -162.38, p < 0.001; time: ß = -18.25, p < 0.001). Pain scores (VAS Time 1) did not differ significantly between groups, and tumor type did not significantly influence outcomes. (4) Conclusions: The SIRIO system enhances neuroprotection efficacy and safety, reducing radiation dose and procedural time during spine tumoral ablation while maintaining consistent pain management outcomes.

Exploring the Efficacy of Combining Radiofrequency Thermal Ablation or Microwave Ablation with Vertebroplasty for Pain Control and Disease Management in Metastatic Bone Disease-A Systematic Review.

BACKGROUND: Interventional radiology techniques have become pivotal in recent years in managing metastatic bone disease, which frequently results in skeletal complications such as fractures and severe pain. Thermoablative methods like radiofrequency ablation (RFA) and microwave ablation (MWA), when combined with vertebroplasty (VP), are proving increasingly beneficial for these patients. METHODS: The search was independently conducted by two radiologists on MEDLINE databases, using specified strings up to April 2024. Methodological quality was assessed using PRISMA guidelines. Studies meeting inclusion criteria investigated thermoablation techniques (RFA and/or MWA) combined with VP, focusing on pain management and disease control outcomes in adults. RESULTS: Among 147 results, 42 articles met the criteria, with varied prospective and retrospective designs and sample sizes averaging 49 patients, predominantly involving RFA (30 studies), MWA (11 studies), and one comparative study. Our review highlights significant pain reduction, effective local tumor control, and favorable safety of combined RFA or MWA with VP, supporting its potential in managing vertebral pathologies and warranting further clinical integration. CONCLUSIONS: The combined treatment of RFA/MWA with VP demonstrates significant pain reduction and local tumor control, with a rapid onset of analgesic effect. These findings support its crucial role in clinical practice for managing vertebral metastases.

Increased Dose in Spine Stereotactic Radiosurgery for Metastatic Disease: Are We Underestimating the Risks?

Background and Objectives: The recently published Spine Stereotactic Radiosurgery (SSRS) ESTRO guidelines advise against treating spinal metastatic disease with a single dose equal to or smaller than 18 Gy, prioritizing local control over the potential for complications. This study aims to assess the necessity and validity of these higher dose recommendations by evaluating the outcomes and experiences with lower radiation doses. Materials and Methods: A retrospective evaluation of SSRS patients treated at a single institute was conducted. The outcomes and complications of this cohort were compared to the current literature and the data supporting the new ESTRO guidelines. Results: A total of 149 treatment sessions involving 242 spinal levels were evaluated. The overall local control rate was 91.2%. The mean radiation dose for the local control group compared to the local failure group was similar (17.5 vs. 17.6 Gy, not significant). The overall complication rate was 6%. These results are consistent with previous publications evaluating SSRS for metastatic spinal disease. Conclusions: SSRS dose escalation may increase local control efficacy but comes with a higher risk of complications. The evidence supporting the strong recommendations in the recent ESTRO guidelines is not robust enough to justify a universal application. Given the palliative nature of treatment for metastatic patients, dose determination should be individualized based on patient conditions and preferences, with a detailed discussion about the risk-benefit ratio of increased doses and the level of evidence supporting these recommendations.

Improved Thoracoscopic-Assisted Surgery for the Treatment of Metastatic Thoracic Vertebral Tumors.

The significant progress made in the diagnosis and treatment of malignant tumors has led to improved patient survival rates. However, the metastatic spread of these tumors to the thoracic vertebrae remains a significant challenge, often resulting in bone-related adverse events, such as pathological fractures and severe complications. To address this issue, a refined multidisciplinary approach has been explored, which utilizes thoracoscopic techniques for tumor resection and spinal interventions. Thoracoscopic techniques offer a minimally invasive alternative to traditional open surgical methods, aiming to reduce the overall trauma experienced by patients. By leveraging the advantages of thoracoscopy, clinicians can effectively resect metastatic tumors within the thoracic vertebrae while minimizing the impact on surrounding tissues and structures. This approach, combined with targeted spinal interventions, has the potential to improve patient outcomes and quality of life by mitigating the debilitating effects of pathological fractures and other complications associated with metastatic bone disease. The implementation of this multidisciplinary strategy, incorporating thoracoscopic tumor resection and spinal interventions, represents a promising avenue for the management of metastatic tumors within the thoracic vertebrae. Further research and clinical evaluation are necessary to fully elucidate the long-term benefits and establish the optimal treatment protocols for this patient population, ultimately enhancing the care and outcomes for individuals afflicted by this challenging condition.

Resection of a giant intraspinal and extraspinal schwannoma with cystic change using a two-step surgery: a case report.

BACKGROUND: Schwannomas originating from the intravertebral canal rarely extend into the paravertebral region or form large masses. There are few reports on such medical cases, and their clinical diagnosis and management are poorly understood. Here, we report a case of an intraspinal schwannoma with a giant extraspinal mass in a middle-aged Chinese woman and the clinical implications of the symptoms, diagnosis, and treatment of thoracic vertebral schwannoma. CASE PRESENTATION: A 59-year-old female patient who presented with sudden lower limb numbness and difficulty in walking was referred to our department. Magnetic resonance imaging (MRI) revealed a tumor compressing the T11-T12 spinal canal and extensively invading the left thoracic cavity to form a giant paravertebral mass. Schwannoma was diagnosed after intraoperative pathological examination, in which tumor cells were immunoreactive to S100 and Sox10 but negative for smooth muscle actin (SMH). Intraspinal mass resection through the posterior approach and extraspinal chest mass resection under video-assisted thoracoscopy through the left lateral approach were performed simultaneously, and instrumentation was used to maintain thoracic spinal stability. CONCLUSION: In patients with large schwannomas, customized treatment plans are crucial. Tailoring the approach to an individual's specific condition by considering factors such as tumor size and location is essential for optimal outcomes.

Comment on, "Decoding pediatric spinal tumors: a single-center retrospective case series on etiology, presentation, therapeutic strategies, and outcomes".

The article "Decoding pediatric spinal tumors: a single-center retrospective case series on etiology, presentation, therapeutic strategies, and outcomes" by Lenga et al. (2024) provides essential insights into pediatric spinal tumors, a rare and challenging area of medical research. The authors present a thorough analysis of clinical presentations, treatment strategies, and patient outcomes, offering valuable data to refine therapeutic approaches and improve outcomes. However, the study's retrospective design, confined to a single center, introduces potential biases and limits the generalizability of findings. The lack of long-term follow-up data and a control group further restricts the study's scope. Future research should prioritize multi-center collaborations, incorporate control groups, and extend follow-up durations to better understand long-term outcomes. The establishment of standardized treatment protocols is also recommended to enhance consistency in managing pediatric spinal tumors across diverse clinical settings.

[Spinal metastases and metastatic spinal cord compression: interpretation for National Institute for Health and Care Excellence (NICE) 2023 guideline].

Spine is a common site of metastasis in patients with malignant tumors, and tumor metastasis to the spine can lead to pain, pathological fractures, and nerve compression. In order to optimize the diagnosis and management of patients with spinal metastases and metastatic spinal cord compression (MSCC), the National Institute for Health and Care Excellence (NICE) in the UK proposed the first diagnostic and treatment guidelines for patients with MSCC (or at risk of MSCC) in 2008. In recent years, with the rapid advancement of spinal surgery and radiotherapy technology, the standardized process of MSCC diagnosis and treatment urgently needs to be updated. In 2023, NICE launched new guidelines for spinal metastases and MSCC. Based on a thorough study of the guidelines, this article discusses and interprets pain management, corticosteroid treatment, application of bisphosphonates and denosumab, tools for assessing spinal stability and prognosis, radiation therapy, surgical timing and approach, etc., providing reference for clinical diagnosis and treatment in China.

AB015. Efficacy and safety of boron neutron capture therapy in managing metastatic spinal tumors: experimental findings.

BACKGROUND: Boron neutron capture therapy (BNCT) is a unique cancer treatment modality that enables precise targeting of tumors at the cellular level. Based on the success observed in nuclear reactors, BNCT now holds promise as a therapeutic approach for treating invasive brain tumors or head and neck cancers. Metastatic spinal tumors have been treated with multidisciplinary interventions such as surgical resection and radiation therapy. Despite recent advantages of radiation therapy, it remains challenging to achieve better quality of life and activity of daily living. The purpose of this study was to evaluate the efficacy and safety of BNCT in metastatic spinal tumor using a mouse model. METHODS: For the in vitro, neutron and photon irradiation was applied to A549 human lung adenocarcinoma cells. The cells were irradiated neutrons with or without p-boronophenylalanine (BPA) 10 µg Boron/mL for a 24-h exposure before neutron irradiation. The difference of biological effect between neutrons and photons was evaluated by colony forming assay. For in vivo, the tumor-bearing mice were intravenously administered BPA (250 mg/kg), followed by measuring biodistribution of boron using inductively coupled plasma atomic emission spectroscopy (ICP-AES). For in vivo BNCT, the mice were randomly assigned to untreated (n=10), neutron irradiation only (n=9), and BNCT groups (n=10). Overall survival and hindlimb function were analyzed. Histopathological examination was also performed to assess the influences of neutron irradiation. RESULTS: Neutron irradiation showed a stronger cell-killing effect than that exhibited by photon irradiation in vitro. For in vivo biodistribution, the highest boron accumulation in the tumor was seen at 2.5-h time point (10.5 µg B/g), with a tumor to normal spinal cord and blood ratios were 3.6 and 2.9, respectively. For the in vivo BNCT, BNCT had significantly prolonged survival (vs. untreated, P=0.002; vs. neutron only, P=0.01, respectively, log-rank test) and preserved mice hindlimb function compared to the other groups (vs. untreated, P<0.001; vs. neutron only, P=0.005, respectively, MANOVA). No adverse events and apparent histopathological changes were observed among three groups. CONCLUSIONS: These findings indicate that BNCT may represent a novel therapeutic option in the management of metastatic spinal tumors.

AB033. Factors related to neuropathic pain in spinal metastasis tumor patients experiencing cancer pain at Dr. Cipto Mangunkusumo Hospital.

BACKGROUND: Spinal metastatic tumors are a common complication in advanced cancer patients, frequently leading to debilitating pain that significantly impairs quality of life. Cancer-related pain can encompass various etiologies, including nociceptive and neuropathic components. Neuropathic pain, arising from nerve damage or dysfunction, presents unique challenges in terms of diagnosis and management. Despite its high prevalence in cancer patients, neuropathic pain often remains underrecognized and undertreated. This study aimed to determine the factors related to neuropathic pain in patients with spinal metastatic tumors who experience cancer pain. METHODS: This study used a retrospective cross-sectional to analyze cancer pain in patients with spinal metastatic tumors. It was conducted at Dr. Cipto Mangunkusumo Hospital using secondary data from January 2023 to January 2024. Prevalence data were calculated using the prevalence formula and expressed as percentages. Normality was assessed using the Kolmogorov-Smirnov test. Chi-square was employed for data management in groups with categorical scales, with Fisher's test used if the requirements for the chi-square test were not met. RESULTS: The study involved 82 patients with spinal metastatic tumors experiencing cancer pain, 51.2% were women. The patients' mean age was 51.5±12.5 years of these patients, 12.2% had lung tumors. The study findings indicate that a significant proportion (73.2%) of patients exhibited tumors with metastases in multiple locations, 61% in thoracal region with the majority (91.5%) experiencing moderate to severe pain intensity. Regarding pain characterization, 9.6% of patients reported neuropathic pain, 47.6% experienced mixed pain, and 42.2% had nociceptive pain. Data analysis found a significant proportion between pain onset (P=0.05), location of lesion (P=0.03), and pain intensity (P=0.01). CONCLUSIONS: This study shows patients with spinal metastatic tumors suffering pure neuropathic pain (9.6%) and mixed type pain (47.6%). Pain onset, location of lesion, and pain intensity were significantly different between types of pain. The high incidence of neuropathic pain and mixed pain serves as a crucial reference for treating patients with cancer pain.

AB049. Surgery for symptomatic spinal metastases-when, what and how?

BACKGROUND: Spine is the most common site for metastases in the skeletal system. Longer lifespans of patients with common cancers are translating into increasing incidence of patients with symptomatic spinal metastases. Surgery for spinal metastases offers immediate neurological decompression with stabilization and preservation of quality-of-life parameters. The objectives of the study were to assess the effect of pre-operative neurological condition, timing, and type of surgery on postoperative neurological function and long-term outcome as well as to analyze the various sources of primary in cases of symptomatic spinal metastases and the spinal level involved in terms of postoperative neurological function and ambulation. METHODS: A retrospective analysis of all operated cases of symptomatic spinal metastases at our institute over a period of 5 years was performed. Parameters such as neurological presentation, timing of surgery, source of primary, and radiological features of the metastases were assessed and compared with the type of surgery performed, post-operative neurological function, and long-term outcome. The in-house hospital information system was to collect data. RESULTS: A total of 94 patients were operated on for symptomatic spinal metastases, the dorsal spine was the most common location and hematological malignancies were the most common primary overall and among men whereas breast was the most common primary in females. Overall, 64.8% of the patients had neurological motor deficits of which 72% had an improvement in motor power. We found that patients with a pre-operative motor power of 3/5 or more likely to have an improvement in post-operative neurological function and ambulatory status. CONCLUSIONS: Surgery for symptomatic spinal metastases plays a vital role in preserving the quality of life of the patients. Patients with preoperative motor power of 3/5, spastic tone, and features of mechanical back pain alone have good ambulatory outcomes post-spine surgery.

AB074. Propensity-score matched analysis to evaluate the safety and utility of intraoperative cell-salvaged autologous blood transfusion in metastatic spine tumour surgery.

BACKGROUND: Blood loss is an important consideration in metastatic spine tumour surgery (MSTS). Allogeneic blood transfusion (ABT) is the current standard of blood replenishment for MSTS despite known complications. Salvaged blood transfusion (SBT) through intraoperative cell salvage addresses the majority of complications related to ABT. However, the use of SBT in MSTS still remains controversial. We aim to conduct a prospective propensity-score (PS) matched analysis to evaluate the long-term clinical outcomes of intraoperative cell salvage (IOCS) in MSTS. METHODS: Our study included 98 patients who underwent MSTS from 2014-2017. A PS matched cohort was created using the relevant and available predictors of treatment assignment and outcomes of interest. Clinical outcomes consisting of overall survival (OS), as well tumour progression (TP) that was evaluated using RECIST (v1.1) were compared in the matched cohort. RESULTS: Our study had a total of 98 patients with a mean age of 60 years old. A total of 33 patients received SBT. Overall median blood loss was 600 mL [interquartile range (IQR): 300-1,000 mL] and overall median blood transfusion (BT) was 620 mL (IQR: 110-1,600 mL). Group PS matching included 30 patients who received ABT and 28 patients who received SBT. There was also no significant difference between the OS of patients who underwent ABT or SBT (P=0.19). SBT did not show any significant increase in 4-year tumour progression [PS matched hazard ratio (HR) 3.659; 95% confidence interval (CI): 0.346-38.7; P=0.28]. CONCLUSIONS: SBT has been shown to have similar clinical outcomes to that of ABT in patients undergoing MSTS, with potential benefits of avoiding complications and costs of ABT. This will be the first long-term PS matched analysis to report on the clinical outcomes of SBT and affirms the clinical role of SBT in MSTS today.

AB075. When would minimally invasive spinal surgery not be preferable for metastatic spine disease?-a narrative review.

BACKGROUND: Metastatic spine tumour surgery (MSTS) is an important treatment modality of metastatic spinal disease (MSD). Open spine surgery (OSS) was previously the gold standard of treatment. However, advancements in MSTS in recent years has resulted in a current paradigm shift towards today's gold standard of minimally invasive spinal surgery (MISS) and early adjuvant RT in treating MSD patients. Nonetheless, there are still certain situations whereby MISS is not desirable or even suitable. There has also yet to be any literature describing the considerations for not using MISS in MSD in today's clinical context. We aim to bridge the gap where OSS should be considered with caution and highlight situations where MISS is preferable using the available literature and personal experience. METHODS: This narrative review was conducted using PubMed, Medical Literature Analysis and Retrieval System Online (MEDLINE), The Cochrane Library and Scopus databases through August 31, 2023. Inclusion criteria for the review were studies with discussion on the type of surgery in MSTS. RESULTS: A total of 52 studies were included in this review. We discussed various advantages and situations appropriate for MISS for MSD in today's clinical context. Nonetheless, there are still various unique circumstances in which MISS may be less suitable. MISS is less feasible in patients of paediatric profile, having short stature or having had previous surgery at the level of operation. Occipitocervical and cervicothoracic location of vertebrae metastasis also makes MISS less feasible due to access and imaging difficulty. MISS for tumours which are hypersclerotic and hypervascular can also result in more difficulty for cannulation of MISS probes as well as control of bleeding respectively, and hence will be less encouraged in the above settings. CONCLUSIONS: Our review will be the first to discuss circumstances in which MISS is less applicable, despite the advantages it may confer over traditional OSS. MSTS should be individualized to the patient, depending on the experience of the surgeon. OSS is still a time-tested approach that holds weight in MSTS and should be readily utilized depending on the clinical situation.

AB081. Experience using CFR-PEEK implants in metastatic and primary spine tumour surgery: a single centre retrospective study.

BACKGROUND: Titanium has been the conventional implant material of choice for fixation in both primary and metastatic spine tumour surgeries (MSTS). However, these implants result in artefact generation during post-operative computed tomography (CT) or magnetic resonance imaging (MRI), resulting in poor planning of radiotherapy (RT) and suboptimal tumour surveillance. Carbon fibre-reinforced polyetheretherketone (CFR-PEEK) implants have gained momentum for instrumentation in MSTS due to their radiolucent properties. This in turn does not sacrifice the biomechanical strength of the implants. In this study, we compared the peri-operative outcomes, post operative imaging artefacts and dosimetricdata of CFR-PEEK implants to titanium implants to asses for potential benefits in post-operative RT planning in patients who underwent MSTS. METHODS: This is a retrospective study involving 42 patients operated for MSTS. Patient-related data including demographics, tumour pathology, intra-operative data, functional outcome, and RT-related data were collected for both groups. All patients were followed-up post-operatively for a minimum of 2 years or until demise, whichever was earlier. RESULTS: In our study, 20 (47.6%) patients had CFR-PEEK implants, while 22 (52.4%) of patients had titanium implants used for MSTS. Both groups of patients had similar clinical outcomes for pain and overall survival predictability pre-operatively (P>0.05). Mean number of levels instrumented by titanium screws were 6.8±2.93, while for the CFR-PEEK screws were 4.07±1.05. Mean volume of artefact generated during post operative CT was 75.1±43.4 mm3 in titanium group and 13.3±14.2 mm3 in CFR-PEEK group (P=0.005). The mean time taken to contour the artefacts was 17.3±5.84 minutes in the titanium group, while the CFR-PEEK group took 9.60±7.17 minutes (P=0.049). CONCLUSIONS: Our study suggests that carbon fibre reinforced PEEK screws significantly reduce artefact generation and the time taken to contour them during post-operative RT planning, while delivering equivalent clinical and functional outcomes as compared to standard titanium implants.