High grade osteosarcoma of the extremities metastatic to the lung: Long-term results in 323 patients treated combining surgery and chemotherapy, 1985–2005

Pulmonary Metastasectomy in Sarcoma

Sarcoma has a predilection to metastasize to the lungs, with pulmonary metastases occurring in up to half of patients with this disease. Resection of metastatic disease is a commonly utilized tool in the management of these patients due to limitations in systemic therapies. Prospective data are absent and recommendations for metastasectomy in the setting of sarcoma are derived from retrospective series. We describe factors associated with survival that should be evaluated in considering surgical candidacy. Approaches to resection along with management of recurrent pulmonary disease are also discussed.

Overview of biodegradable materials for bone repair and osteosarcoma treatment: From bulk to scaffolds

Osteosarcoma, the most common type of malignant bone tumor that affects growing bones in teenagers and children, has become a significant challenge for medical science. The combination of chemotherapy and surgery has been the standard treatment strategy for decades. However, concerns about tumor recurrence and the toxic effects of the drugs continue to drive materials scientists to develop multifunctional scaffolds that can simultaneously support bone regeneration and prevent tumor recurrence. Emergent multifunctional scaffolds have the potential to foster essential and dynamic cellular communication, which can directly target, signal, stimulate, and enhance the body's natural bone repair response. This review emphasizes the mechanisms involved and highlights various technologies and manufacturing processes that align with the capability of these scaffolds to effectively promote bone repair, especially in the presence of osteosarcoma. Additionally, the review summarizes the current state of knowledge regarding scaffolds based on magnesium (Mg), zinc (Zn), and iron (Fe), as well as the antitumor properties of their corrosion products. The review also discusses the therapeutic potential of Mg-, Zn-, and Fe-based materials in inhibiting osteosarcoma cell proliferation. The article elaborates on the main research challenges and prospects of biodegradable materials for bone repair and osteosarcoma treatment.

Current Surgical Approach to Pulmonary Metastasectomy

The lung is a common site of metastases for children and adolescents with a wide variety of solid tumors. The role for pulmonary metastasectomy is dictated by tumor histology and can serve either therapeutic or diagnostic purposes. Careful surgical planning is required to determine the optimal surgical approach and to ensure successful nodule localization. While high level data are limited, in appropriate situations pulmonary metastasectomy can confirm staging, guide therapy, improve survival, and reduce the need for other therapy escalations.

The origin and polarization of Macrophages and their role in the formation of the Pre-Metastatic niche in osteosarcoma

Osteosarcoma, a primary malignant bone tumor commonly found in adolescents, is highly aggressive, with a high rate of disability and mortality. It has a profound negative impact on both the physical and psychological well-being of patients. The standard treatment approach, comprising surgery and chemotherapy, has seen little improvement in patient outcomes over the past several decades. Once relapse or metastasis occurs, prognosis worsens significantly. Therefore, there is an urgent need to explore new therapeutic approaches. In recent years, the successful application of immunotherapy in certain cancers has demonstrated its potential in the field of cancer treatment. Macrophages are the predominant components of the immune microenvironment in osteosarcoma and represent critical targets for immunotherapy. Macrophages exhibit dual characteristics; while they play a key role in maintaining tumor-promoting properties within the microenvironment, such as inflammation, angiogenesis, and immune suppression, they also possess antitumor potential as part of the innate immune system. A deeper understanding of macrophages and their relationship with osteosarcoma is essential for the development of novel therapeutic strategies.

Evaluation of Indoleamine 2,3-Dioxygenase (IDO) Expression in Osteosarcoma: Insights From a 10-Year Retrospective Cohort

Introduction

Osteosarcoma, a prevalent bone malignancy in children and adolescents, is currently treated through surgical resection and chemotherapy. Advancements in cancer research are targeting immune checkpoint molecules, such as indoleamine 2,3-dioxygenase, to advance the development of immunotherapy. However, the scarcity of research on IDO in osteosarcoma results in an absence of comprehensive data, highlighting the conflicting findings surrounding IDO's role in various cancers. Our study aims to explore IDO expression in primary tumors and metastatic lesions among osteosarcoma patients, investigating its association with clinicopathological characteristics and assessing its impact on survival outcomes.

Methods

150 patients diagnosed with osteosarcoma were selected between 2009 and 2019 from the Shaukat Khanum Memorial Cancer Hospital and Research Centre, Lahore, Pakistan. FFPE tissue samples of primary tumors and metastatic lesions were retrieved to conduct immunohistochemical analysis. Moreover, the clinicopathological data of these patients were gathered from the hospital information system.

Results

Out of 150 patients, primary tumors were accessible for 134 individuals, while metastatic lesions were available for 49 patients. IDO expression was identified in 9 (6.71%) primary tumors and 2 (4.08%) metastatic lesions among osteosarcoma patients. Furthermore, 3 patients exhibited high expression (27.3%), while 8 displayed low IDO expression (72.7%).

Conclusion

Our comprehensive study findings indicate that most osteosarcoma patients do not exhibit expression of IDO. This absence of expression aligns with the characteristic "cold" tumor microenvironment observed in osteosarcoma. Further investigations are imperative to provide deeper insights into the intricacies of this immunomodulatory factor in the context of osteosarcoma.

Ailanthone targets the KMT2A-MEN1 complex to suppress lung metastasis of osteosarcoma

BACKGROUND

Lung metastasis is the leading cause of death in patients with osteosarcoma (OS), and new drugs are urgently needed. Epigenetic reprogramming is a recently proposed hallmark of malignancy; therefore, targeting epigenetic enzymes might provide a novel therapeutic strategy for OS lung metastasis. We recently reported that ailanthone (AIL), a natural product isolated from the Chinese medicinal plant Ailanthus altissima, inhibits OS cell growth and induces substantial metabolic changes; however, its direct targets remain unclear.

PURPOSE

To identify the direct targets of AIL in OS and to explore the effects of AIL on OS lung metastasis in vivo.

STUDY DESIGN

Direct target proteins of AIL and downstream signaling pathways were identified in Saos-2 and U-2OS OS cells. The in vivo effects of AIL on OS lung metastasis were investigated using a mouse model.

METHODS

A novel surface plasmon resonance-high-performance liquid chromatography-mass spectrometry (SPR-HPLC-MS) assay was used to determine direct targets of AIL in OS. A cellular thermal shift assay, molecular docking analysis, enzyme activity assay, qRT-PCR, western blotting, chromatin immunoprecipitation assay, and reverse tests were performed to confirm the target and downstream pathway of AIL. A tumor xenograft model was used to verify the efficacy and mechanisms in vivo.

RESULTS

Histone-lysine N-methyltransferase 2A (KMT2A) together with its scaffold protein menin (MEN1) were identified as direct target proteins of AIL in OS. AIL induced the autophagic degradation of the KMT2A-MEN1 complex. Moreover, AIL inhibited intracellular H3K4 methyltransferase activity and epigenetically inhibited the transcription of genes in the serine biosynthetic pathway (SSP). Furthermore, AIL suppressed OS lung metastasis and downregulated KMT2A, MEN1, and SSP in mouse models.

CONCLUSION

This work showed that AIL targets the KMT2A-MEN1 complex and inhibits SSP to suppress OS lung metastasis. Notably, AIL exhibits new mechanisms of action, distinct from those of existing anti-OS drugs. On the basis of these findings, we proposed a novel strategy to treat OS by targeting epigenetic enzymes and cancer metabolism.

Magnetic Resonance Imaging Texture Analysis Based on Intraosseous and Extraosseous Lesions to Predict Prognosis in Patients with Osteosarcoma

Objectives: To construct an optimal magnetic resonance imaging (MRI) texture model to evaluate histological patterns and predict prognosis in patients with osteosarcoma (OS). Methods: Thirty-four patients underwent pretreatment MRI and were diagnosed as having OS by surgical resection or biopsy between September 2008 and June 2018. Histological patterns and 3-year survival were recorded. Manual segmentation was performed in intraosseous, extraosseous, and entire lesions on T1-weighted, T2-weighted, and contrast-enhanced T1-weighted images to extract texture features and perform principal component analysis. A support vector machine algorithm with 3-fold cross-validation was used to construct and validate the models. The area under the receiver operating characteristic curve (AUC) was calculated to evaluate diagnostic performance in evaluating histological patterns and 3-year survival. Results: Eight patients were chondroblastic and the remaining twenty-six patients were non-chondroblastic patterns. Twenty-seven patients were 3-year survivors, and the remaining seven patients were non-survivors. In discriminating chondroblastic from non-chondroblastic patterns, the model from extraosseous lesions on the T2-weighted images showed the highest diagnostic performance (AUCs of 0.94 and 0.89 in the training and validation sets). The model from intraosseous lesions on the T1-weighted images showed the highest diagnostic performance in discriminating 3-year non-survivors from survivors (AUCs of 0.99 and 0.88 in the training and validation sets) with a sensitivity, specificity, positive predictive value, and negative predictive value of 85.7%, 92.6%, 75.0%, and 96.2%, respectively. Conclusions: The texture models of extraosseous lesions on T2-weighted images can discriminate the chondroblastic pattern from non-chondroblastic patterns, while the texture models of intraosseous lesions on T1-weighted images can discriminate 3-year non-survivors from survivors.

Osteosarcoma Metastasis to the Thorax: A Pictorial Review of Chest Computed Tomography Findings

Background: Osteosarcoma, a primary bone malignancy in children and adolescents, frequently metastasizes to the lungs, contributing significantly to morbidity and mortality. Lung Metastases: At diagnosis, 15-20% of patients present with detectable lung metastases. Chest computed tomography (CT) is vital for the early detection and monitoring of these metastases. Lung involvement typically presents as multiple nodules of varying sizes and can include atypical features such as cavitation, cystic lesions, ground-glass halos, intravascular tumor thrombi, and endobronchial disease. Additional Findings: Pleural metastasis often occurs alongside pulmonary disease, and complications like spontaneous pneumothorax may arise. Additional findings may include thoracic lymphadenopathy, cardiac tumor thrombus, and chest wall deposits. Conclusion: Familiarity with these imaging patterns is essential for radiologists to ensure timely diagnosis and effective management. This review highlights the critical role of chest CT in detecting and characterizing osteosarcoma metastasis.

The BET PROTAC inhibitor GNE-987 displays anti-tumor effects by targeting super-enhancers regulated gene in osteosarcoma

BACKGROUND

Osteosarcoma (OS) is one of the most common primary malignant tumors of bone in children, which develops from osteoblasts and typically occurs during the rapid growth phase of the bone. Recently, Super-Enhancers(SEs)have been reported to play a crucial role in osteosarcoma growth and metastasis. Therefore, there is an urgent need to identify specific targeted inhibitors of SEs to assist clinical therapy. This study aimed to elucidate the role of BRD4 inhibitor GNE-987 targeting SEs in OS and preliminarily explore its mechanism.

METHODS

We evaluated changes in osteosarcoma cells following treatment with a BRD4 inhibitor GNE-987. We assessed the anti-tumor effect of GNE-987 in vitro and in vivo by Western blot, CCK8, flow cytometry detection, clone formation, xenograft tumor size measurements, and Ki67 immunohistochemical staining, and combined ChIP-seq with RNA-seq techniques to find its anti-tumor mechanism.

RESULTS

In this study, we found that extremely low concentrations of GNE-987(2-10 nM) significantly reduced the proliferation and survival of OS cells by degrading BRD4. In addition, we found that GNE-987 markedly induced cell cycle arrest and apoptosis in OS cells. Further study indicated that VHL was critical for GNE-987 to exert its antitumor effect in OS cells. Consistent with in vitro results, GNE-987 administration significantly reduced tumor size in xenograft models with minimal toxicity, and partially degraded the BRD4 protein. KRT80 was identified through analysis of the RNA-seq and ChIP-seq data. U2OS HiC analysis suggested a higher frequency of chromatin interactions near the KRT80 binding site. The enrichment of H3K27ac modification at KRT80 was significantly reduced after GNE-987 treatment. KRT80 was identified as playing an important role in OS occurrence and development.

CONCLUSIONS

This research revealed that GNE-987 selectively degraded BRD4 and disrupted the transcriptional regulation of oncogenes in OS. GNE-987 has the potential to affect KRT80 against OS.

Predictors of pulmonary metastases on chest computed tomography in children and adolescents with osteosarcoma-tips for qualifying patients for thoracotomy

BACKGROUND

Osteosarcoma is the most common primary malignant bone tumour in children and adolescents. Lungs are the most frequent and often the only site of metastatic disease. The presence of pulmonary metastases is a significant unfavourable prognostic factor. Thoracotomy is strongly recommended in these patients, while computed tomography (CT) remains the gold imaging standard. The purpose of our study was to create tools for the CT-based qualification for thoracotomy in osteosarcoma patients in order to reduce the rate of useless thoracotomies.

METHODS

Sixty-four osteosarcoma paediatric patients suspected of lung metastases on CT and their first-time thoracotomies (n = 100) were included in this retrospective analysis. All CT scans were analysed using a compartmental evaluation method based on the number and size of nodules. Calcification and location of lung lesions were also analysed. Inter-observer reliability between two experienced radiologists was assessed. The CT findings were then correlated with the histopathological results of thoracotomies. Various multivariate predictive models (logistic regression, classification tree and random forest) were built and predictors of lung metastases were identified.

RESULTS

All applied models proved that calcified nodules on the preoperative CT scan best predict the presence of pulmonary metastases. The rating of the operated lung on the preoperative CT scan, dependent on the number and size of nodules, and the total number of nodules on this scan were also found to be important predictors. All three models achieved a relatively high sensitivity (72-92%), positive predictive value (81-90%) and accuracy (74-79%). The positive predictive value of each model was higher than of the qualification for thoracotomy performed at the time of treatment. Inter-observer reliability was at least substantial for qualitative variables and excellent for quantitative variables.

CONCLUSIONS

The multivariate models built and tested in our study may be useful in the qualification of osteosarcoma patients for metastasectomy through thoracotomy and may contribute to reducing the rate of unnecessary invasive procedures in the future.

Survival analysis and prognostic model establishment of secondary osteosarcoma: a SEER-based study

Background

Surgical excision is considered one of the most effective treatments for secondary osteosarcoma (SO). It remains unclear whether the survival of patients with secondary osteosarcoma (SO) could be associated with their surgical willingness.

Materials and methods

The statistics of the patients diagnosed with SO between 1975 and 2008 were gathered from the surveillance epidemiology and end results (SEER) database. The patients were divided into three subgroups according to their surgical compliance. The authors used the multivariable Logistic regression analysis and cox regression method to reveal the influence of surgical compliance on prognosis and the risk factors of surgical compliance. Additionally, the authors formulated a nomogram model to predict the overall survival (OS) of patients. The concordance index (C-index) was used to evaluate the accuracy and practicability of the above prediction model.

Results

Sixty-three (9.2%) of the 688 patients with SO who were recommended for surgical treatment refused to undergo surgery. Lower surgical compliance can be ascribed to an earlier time of diagnosis and refusal of chemotherapy. The lower overall survival (OS) {[hazard ratio (HR)] 1.733, [CI] 1.205-2.494, P value [P]=0.003} of not surgical compliant patients was verified by the multivariate cox regression method, compared with surgical compliant patients. In addition, the discernibility of the nomogram model was proven to be relatively high (C-index=0.748), by which we can calibrate 3-year- and 5-year OS prediction plots to obtain good concordance to the actual situation.

Conclusions

Surgical compliance was proved to be an independent prognostic factor in the survival of patients with SO.

Trap-Door Thoracotomy and Clamshell Thoracotomy as Surgical Approaches for Neuroblastoma and Other Thoracic Tumors in Children

Solid tumors of the cervicothoracic junction, the posterior mediastinum, or bilateral dorsal thoracic tumors represent a challenge in pediatric surgical oncology. The aim of this study was to evaluate trap-door thoracotomy and clamshell thoracotomy as surgical approaches. A single-center retrospective study of children with solid tumors in these specific localizations was performed. From 2015 to 2023, 26 children (17 girls; 9 boys) were treated at a median age of 54 months (range 8-229). Tumor resection was performed for neuroblastoma (n = 11); metastatic disease (n = 7); malignant rhabdoid tumor (n = 4); Ewing sarcoma (n = 1); inflammatory myofibroblastic tumor (n = 1); rhabdomyosarcoma (n = 1); and neurofibroma (n = 1). The surgical goal of macroscopic complete excision was achieved in all of the 14 children who underwent trap-door thoracotomy and in 11 of the 12 children who underwent clamshell thoracotomy. There were no major complications. At a median follow-up of 8 months (range 0-60), the disease was under local control or in complete remission in 66.7% of the children. In conclusion, surgical resection of solid tumors of the cervicothoracic junction in children can be performed safely and successfully with trap-door thoracotomy and with clamshell thoracotomy for posterior mediastinal or bilateral dorsal thoracic tumors.

Epidemiology and nomogram of pediatric and young adulthood osteosarcoma patients with synchronous lung metastasis: A SEER analysis

BACKGROUND

Patients with osteosarcoma and synchronous lung metastasis (SLM) have poor survival. This study aimed to explore the epidemiology data and construct a predictive nomogram to identify cases at risk of SLM occurrence among pediatric and young adulthood osteosarcoma patients.

METHODS

All data were extracted from Surveillance, Epidemiology, and End Results 17 registries. The age-standardized incidence rate (ASIR) and annual percentage change was evaluated, and reported for the overall population and by age, gender, race, and primary site. Univariate and multivariate logistic regression analyses were used to identify risk factors associated with SLM occurrence, then significant factors were used to develop the nomogram. The area under the receiver operating characteristic curve (AUC) and calibration curve were used to evaluated the predictive power of the nomogram. Survival analysis was assessed by the Kaplan-Meier method and the log-rank test. Multivariate Cox analysis was used to determine the prognostic factors.

RESULTS

A total of 278 out of 1965 patients (14.1%) presented with SLM at diagnosis. The ASIR increased significant from 0.46 to 0.66 per 1,000,000 person-years from year 2010 to 2019, with an annual percentage change of 3.5, mainly in patients with age 10-19 years, male and appendicular location. All patients were randomly assigned into train cohort and validation cohort with a spilt of 7:3. In the train cohort, higher tumor grade, bigger tumor size, positive lymph nodes and other site-specific metastases (SSM) were identified as significant risk factors associated with SLM occurrence. Then a nomogram was developed based on the four factors. The AUC and calibration curve in both train and validation cohorts demonstrated that the nomogram had moderate predictive power. The median cancer-specific survival was 25 months. Patients with age 20-39 years, male, positive lymph nodes, other SSM were adverse prognostic factors, while surgery was protective factor.

CONCLUSIONS

This study performed a comprehensive analysis regarding pediatric and young adulthood osteosarcoma patients had SLM. A visual, clinically operable, and easy-to-interpret nomogram model was developed for predicting the risk of SLM, which could be used in clinic and help clinicians make better decisions.

Orthopedic approaches for bone sarcoma: A bibliometric review of the 50 most cited papers

Background

Curative treatment of bone sarcoma is primarily based on operative management. The Orthopedic Oncology approach towards this disease has evolved greatly to the breakthrough in systemic treatment options as well as unique implant designs favoring limb salvage over amputations. The purpose of this study was to perform a bibliometric analysis of the top 50 most cited papers related to the orthopedic the approach to bone sarcomas.

Methods

We queried the ISI Web of Knowledge database in July 2022. Keywords utilized were: ""Bone Sarcoma" OR "Osteosarcoma" OR "Ewing Sarcoma" OR "Chondrosarcoma" OR "Chordoma". The top 50 articles pertaining to the orthopedic approach to bone sarcoma were included for analysis and included manuscript title, authors, citation count, journal and publication year.

Results

The mean number of citations are 187.06 (Range 125-400; SD 67.83). The average citations per year is 10.03 (Range 47.86-3.43; SD 8.05). Many articles were published from 2000 to 2009 (n = 20) and 1990-1999 (n = 13). The majority of the articles were published by institutions within the United States (n = 32). The most common level of evidence was level IV (n = 37). Majority of the articles focused on treatment outcome (n = 22).

Conclusion

This study offers a comprehensive review of the most cited literature regarding orthopedic approaches to bony sarcomas. Modern treatment approaches for bone sarcoma has resulted in an increased focus within the literature on achieving disease free survival wide tissue margins. Understanding the trends of available studies allows for physicians and researchers to target and innovate future areas of study.

Lung metastasectomy for osteosarcoma in children, adolescents, and young adults: proof of permanent cure

INTRODUCTION

Surgical resection of pulmonary metastases has been associated with increased survival at 5 years for osteosarcoma, but limited information is available on long-term outcome, role of repeated metastasectomies, and surgical sequelae in a pediatric population. We analyzed a consecutive series of children, adolescents, and young adults (AYA) treated by repeated lung metastasectomies during a period >40 years to estimate the clinical benefit and potential cure rate of salvage surgery.

METHODS

All patients who underwent lung metastasectomy for osteosarcoma at the IRCCS Istituto Ortopedico Rizzoli of Bologna, University of Modena, and IRCCS Istituto Nazionale Tumori of Milan from May 1973 to January 2014 were included. Overall survival (OS) at 20 years from the first metastasectomy was calculated.

RESULTS

A total of 463 consecutive children and AYA were analyzed. Median age was 15.9 years (range 0.2-23.2 years) and median follow-up 18.6 years. The 5- and 20-year OS were 34.0% and 29.7% (95% CI 25.5-34.0%). Among the 138 (29.8%) alive patients, 42 (30.4%) had disease recurrence cured by repeated metastasectomies. Disease-free interval from primary tumor, number of metastases, and complete resection were the most relevant survival predictors at multivariable model analysis.

DISCUSSION

The extended follow-up of this consecutive series shows that repeated lung metastasectomy can achieve a permanent cure when offered to properly selected patients with metastases from osteosarcoma.

Controversies and Challenges in the Management of Osteosarcoma-an Indian Perspective

Osteosarcoma (OGS) is the most common primary bone tumor in children and adolescents which requires a multidisciplinary approach to management. Although chemotherapy and surgery can cure more than half of localized OGS cases, the unique challenges faced by resource-limited countries like India make this outcome difficult to achieve. Various questions in the management of OGS including role of high-dose methotrexate (HDMTX) in neoadjuvant setting, triplet vs doublet chemotherapy, intensification of chemotherapy based on response in setting of doublet, and indigenous prosthesis in setting of limb salvage need to be defined. Similarly, in the metastatic and recurrent setting, questions regarding intent of treatment, indications of chemotherapy, timing of surgery, and role of targeted therapies need clarification. Lack of randomized trials from India makes definite conclusions difficult, but an attempt can be made to define the best approach in the Indian scenario from available evidence. Hence, a critical review of literature from India and the West was done to define possible management approaches and highlight the lacuna for future research.

Current Status and Prospects of Targeted Therapy for Osteosarcoma

Osteosarcoma (OS) is a highly malignant tumor occurring in bone tissue with a high propensity to metastasize, and its underlying mechanisms remain largely elusive. The OS prognosis is poor, and improving the survival of OS patients remains a challenge. Current treatment methods such as surgical approaches, chemotherapeutic drugs, and immunotherapeutic drugs remain ineffective. As research progresses, targeted therapy is gradually becoming irreplaceable. In this review, several treatment modalities for osteosarcoma, such as surgery, chemotherapy, and immunotherapy, are briefly described, followed by a discussion of targeted therapy, the important targets, and new technologies for osteosarcoma treatment.

ACR Appropriateness Criteria® Malignant or Aggressive Primary Musculoskeletal Tumor-Staging and Surveillance: 2022 Update

Malignant or aggressive primary musculoskeletal tumors are rare and encompass a wide variety of bone and soft tissue tumors. Given the most common site for metastasis from these primary musculoskeletal tumors is to the lung, chest imaging is integral in both staging and surveillance. Extrapulmonary metastases are rarely encountered with only a few exceptions. Following primary tumor resection, surveillance of the primary tumor site is generally recommended. Local surveillance imaging recommendations differ between primary tumors of bone origin versus soft tissue origin. This document consolidates the current evidence and expert opinion for the imaging staging and surveillance of these tumors into five clinical scenarios. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer-reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which peer-reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Prognostic Nomogram of Osteocarcinoma after Surgical Treatment

Purpose

This study aimed to establish a valid prognostic nomogram for osteocarcinoma after surgical management.

Methods

Based on the SEER database, we retrieved the clinical variables of patients confirmed to have osteocarcinoma between 1975 and 2016. Then, we performed univariate and multivariate analyses and constructed a nomogram of overall survival.

Results

Multivariate analysis of the primary cohort revealed that the independent factors for survival were age, grade, pathologic stage, T stage, and surgery performed. All these factors were showed by the nomogram. The correction curve of survival probability showed that the prediction results of nomogram well agreed with the actual observation results. The C index of the nomogram used to predict survival was 0.82; the AUC of 1-year, 3-year, and 5-year survival rates in the training cohort were 0.9, 0.819, and 0.80631, respectively, indicating that the model was accurate and reliable; whether the operation was performed or not; T stage; grade; and age were the main factors affecting the survival of patients. The AUC of the validation cohort for 1 year, 3 years, and 5 years were 0.8, 0.831, and 0.80023, respectively.

Conclusion

The proposed nomogram can more accurately predict the prognosis of patients with osteocarcinoma after surgical management. This could be a potential method that services clinical work.

METTL3 Contributes to Osteosarcoma Progression by Increasing DANCR mRNA Stability via m6A Modification

Background: Osteosarcoma (OS) is the most prevalent bone cancer among children and adolescents, with relatively high mortality rates. RNA N6-methyladenosine (m6A) is the most common human mRNA modification with diverse functions in a variety of biological processes. Previous studies indicated that methyltransferase-like 3 (METTL3), the first methyltransferase to be identified, acted as an oncogene or tumor suppressor in multiple human cancers. However, its functions and underlying mechanisms in OS progression remain unclear; therefore, we explored these processes.

Methods: We used real-time quantitative PCR (RT-qPCR) and Western blot assays to explore METTL3 expression in OS tumor tissues and five OS cell lines to assess its clinical significance. To further examine the functional role of METTL3 during OS progression, CCK-8 analyses, transwell assays, and xenograft model studies were conducted after silencing METTL3. Additionally, underlying mechanisms were also explored using RIP-seq and RIP-qPCR approaches.

Results: METTL3 was upregulated in OS tumor tissues and cell lines and was associated with a worse prognosis. Moreover, METTL3 silencing suppressed OS cell proliferation, migration, and invasion. Also, in vivo METTL3 oncogenic functions were confirmed in the xenograft model. Comprehensive mechanistic analyses identified long non-coding RNA (lncRNA) DANCR as a potential target of METTL3, as indicated by reduced DANCR levels after METTL3 silencing. Also, lncRNA DANCR knockdown repressed OS cell proliferation, migration, and invasion. Furthermore, both METTL3 and lncRNA DANCR silencing significantly suppressed OS growth and metastasis. Finally, we hypothesized that METTL3 regulated DANCR expression via m6A modification-mediated DANCR mRNA stability.

Conclusion: METTL3 contributes to OS progression by increasing DANCR mRNA stability via m6A modification, meaning that METTL3 may be a promising therapeutic target for OS treatment.

Prospero homeobox 1 promotes proliferation, migration, and invasion of osteosarcoma cells and its clinical significance

Osteosarcoma (OS) is the most common primary malignant bone tumor. Prospero homeobox 1 (PROX1) is a key transcription factor involved in some cancers, but the role of PROX1 in OS is unclear. This study aimed to explore the clinical and biology significance of PROX1 in OS. Fifty-four OS tissues and matched nontumor tissues were collected to explore the relationship between PROX1 expression and clinical characteristics and prognosis. qRT-PCR and immunohistochemistry were used to investigate the expression patterns of PROX1 in OS tissues and cells. CCK-8, wound healing, and transwell assays were used to detect the effects of PROX1 on the proliferation, migration, and invasion of OS cells. Transcriptome sequencing, bioinformatics analysis and qRT-PCR were used to explore the regulatory network of PROX1. PROX1 was significantly higher in OS tissues and cells compared to normal tissues and cell lines. In OS patients, high expression of PROX1 was associated with Enneking stage (P < 0.001) and M classification (P < 0.001). High PROX1 expression predicted a poorer overall survival (P = 0.0047). Compared with untreated cells, OS cells overexpressing PROX1 showed higher proliferation, migration, and invasion abilities, while knockdown of PROX1 suppressed these abilities. The results of Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis revealed that the down regulated genes were mainly enriched in TNF signaling pathway, MAPK signaling pathway, and neuroactive ligand-receptor interaction. High PROX1 expression was significantly associated with poor overall survival in OS patients. PROX1 may be a promising prognostic marker and therapeutic target for OS patients.

A Role of CXCL1 Drives Osteosarcoma Lung Metastasis via VCAM-1 Production

Osteosarcoma, a common aggressive and malignant cancer, appears in the musculoskeletal system among young adults. The major cause of mortality in osteosarcoma was the recurrence of lung metastases. However, the molecular mechanisms of metastasis involved in osteosarcomas remain unclear. Recently, CXCL1 and CXCR2 have been crucial indicators for lung metastasis in osteosarcoma by paracrine releases, suggesting the involvement of directing neutrophils into tumor microenvironment. In this study, overexpression of CXCL1 has a positive correlation with the migratory and invasive activities in osteosarcoma cell lines. Furthermore, the signaling pathway, CXCR2/FAK/PI3K/Akt, is activated through CXCL1 by promoting vascular cell adhesion molecule 1 (VCAM-1) via upregulation of nuclear factor-kappa B (NF-κB) expression and nuclear translocation. The in vivo animal model further demonstrated that CXCL1 serves as a critical promoter in osteosarcoma metastasis to the lung. The correlated expression of CXCL1 and VCAM-1 was observed in the immunohistochemistry staining from human osteosarcoma specimens. Our findings demonstrate the cascade mechanism regulating the network in lung metastasis osteosarcoma, therefore indicating that the CXCL1/CXCR2 pathway is a worthwhile candidate to further develop treatment schemas.

Osteosarcoma: An Evolving Understanding of a Complex Disease

Osteosarcoma is the most common primary bone sarcoma and affects both children and adults. The cornerstone of treatment for patients with localized and oligometastatic disease remains neoadjuvant chemotherapy, surgical resection of all sites of disease, followed by adjuvant chemotherapy. This approach is associated with up to an 80% 5-year survival. However, survival of patients with metastatic disease remains poor, and overall, osteosarcoma remains a challenging disease to treat. Advances in the understanding of molecular drivers of the disease, identification of poor prognostic factors, development of risk-stratified treatment protocols, successful completion of large collaborative trials, and surgical advances have laid the ground work for progress. Advances in computer navigation, implant design, and surgical techniques have allowed surgeons to improve patients' physical functional without sacrificing oncologic outcomes. Future goals include identifying effective risk stratification algorithms which minimize patient toxicity while maximizing oncologic outcomes and continuing to improve the durability, function, and patient acceptance of oncologic reconstructions.

Treatment of 120 adult osteosarcoma patients with metachronous and synchronous metastases: A retrospective series of the French Sarcoma Group

Treatment options for metastatic osteosarcomas are scarce. Following failure of standard first line therapy, patients who relapse present a challenging treatment dilemma, and have a poor prognosis. Surgical removal of all metastases is essential. A retrospective analysis of patients with metastatic osteosarcomas was conducted in 15 French Sarcoma Group centers. From January 2009 to December 2018, we identified 120 adult patients; 36 with synchronous and 84 with metachronous metastases with 74 males and 46 females. Mean age was 30 years (18-53). Metastatic sites were lung, bone and other in 91, 11 and 24 patients, respectively. Mean time to first metachronous metastases was 22 months (4-97). All patients except 13 (10.8%) with metachronous metastases received a first line systemic treatment for relapse, and 39 patients (32.5%) were included in a clinical trial. Eighty-one patients (67.5%) had local treatment of distant metastases. Median progression free survival (PFS) and overall survival (OS) were 5.5 (95% CI 4.6-6.4) and 20.5 months (95% CI 13.2-27.7) respectively for the overall group. In multivariate analysis, more than five metastases, time to first metastases <24 months, were statistically significant negative prognostic factors for OS and PFS (P = .002, ≤.001 and P = .006, ≤.001, respectively). Surgery of metastases was associated with better prognosis on OS and PFS (P = .001 and .037, respectively). The presence of bone metastases was a negative prognostic factor on OS but not on PFS (P = .021). In reference sarcoma centers, relapsed osteosarcoma patients with more than one metastasis commonly receive more than one line of systemic therapy, and are included in clinical trial if available.

Platelet-derived lysophosphatidic acid mediated LPAR1 activation as a therapeutic target for osteosarcoma metastasis

Osteosarcoma is the most common primary malignant bone cancer, with high rates of pulmonary metastasis. Osteosarcoma patients with pulmonary metastasis have worse prognosis than those with localized disease, leading to dramatically reduced survival rates. Therefore, understanding the biological characteristics of metastatic osteosarcoma and the molecular mechanisms of invasion and metastasis of osteosarcoma cells will lead to the development of innovative therapeutic intervention for advanced osteosarcoma. Here, we identified that osteosarcoma cells commonly exhibit high platelet activation-inducing characteristics, and molecules released from activated platelets promote the invasiveness of osteosarcoma cells. Given that heat-denatured platelet releasate maintained the ability to promote osteosarcoma invasion, we focused on heat-tolerant molecules, such as lipid mediators in the platelet releasate. Osteosarcoma-induced platelet activation leads to abundant lysophosphatidic acid (LPA) release. Exposure to LPA or platelet releasate induced morphological changes and increased invasiveness of osteosarcoma cells. By analyzing publicly available transcriptome datasets and our in-house osteosarcoma patient-derived xenograft tumors, we found that LPA receptor 1 (LPAR1) is notably upregulated in osteosarcoma. LPAR1 gene KO in osteosarcoma cells abolished the platelet-mediated osteosarcoma invasion in vitro and the formation of early pulmonary metastatic foci in experimental pulmonary metastasis models. Of note, the pharmacological inhibition of LPAR1 by the orally available LPAR1 antagonist, ONO-7300243, prevented pulmonary metastasis of osteosarcoma in the mouse models. These results indicate that the LPA-LPAR1 axis is essential for the osteosarcoma invasion and metastasis, and targeting LPAR1 would be a promising therapeutic intervention for advanced osteosarcoma.

Advancing therapy for osteosarcoma

Improving the survival of patients with osteosarcoma has long proved challenging, although the treatment of this disease is on the precipice of advancement. The increasing feasibility of molecular profiling together with the creation of both robust model systems and large, well-annotated tissue banks has led to an increased understanding of osteosarcoma biology. The historical invariability of survival outcomes and the limited number of agents known to be active in the treatment of this disease facilitate clinical trials designed to identify efficacious novel therapies using small cohorts of patients. In addition, trial designs will increasingly consider the genetic background of the tumour through biomarker-based patient selection, thereby enriching for clinical activity. Indeed, osteosarcoma cells are known to express a number of surface proteins that might be of therapeutic relevance, including B7-H3, GD2 and HER2, which can be targeted using antibody-drug conjugates and/or adoptive cell therapies. In addition, immune-checkpoint inhibition might augment the latter approach by helping to overcome the immunosuppressive tumour microenvironment. In this Review, we provide a brief overview of current osteosarcoma therapy before focusing on the biological insights from the molecular profiling and preclinical modelling studies that have opened new therapeutic opportunities in this disease.

State-of-the-art, approved therapeutics for the pharmacological management of osteosarcoma

Introduction: Advances in the treatment of osteosarcoma (OS) came in the mid-1970s, when adding chemotherapy to surgery significantly improved patient survival. OS outcomes have since plateaued, however, despite exhaustive clinical investigations.Area covered: This review focuses on the most significant recent results of trials (in phases II and III) on localized and metastatic/relapsing OS and offers an overview of new targeted drugs.Expert opinion: Recent findings confirm the MAP (methotrexate, doxorubicin, and cisplatin) regimen as the gold standard for OS patients, also in metastatic cases, and the inefficacy of augmenting or modifying chemotherapy in poor responder patients. Immunotherapy and several tyrosine kinase inhibitors seem to be effective and promising in the treatment of OS. Optimizing the use of active drugs available by personalizing chemotherapies might prove important in the future. We urgently need bench-to-bedside research on OS. This will need to involve the extensive sequencing and immunoprofiling of all resected tumor tissue to find new therapeutic agents, especially for relapsing/metastatic patients. The low incidence of OS, its genomic complexity, and differences within and between tumors combine to complicate efforts to elucidate the biology of this disease. This means that we need to pool the resources of different groups studying OS and support translational research.

Number of metastases and their response to chemotherapy impact survival of patients with isolated lung metastases from bone-derived sarcoma

Background

Pulmonary metastasectomy (PM) is an established treatment for selected patients with metastatic sarcomas. The aim of this study was to examine our institutional experience and evaluate factors predicting outcome.

Methods

We retrospectively reviewed all patients undergoing PM for bone sarcoma in our center from 2001 to 2019. Survival was calculated from the date of PM. Impact on survival of clinical parameters was assessed.

Results

Thirty-eight patients (27 males, 71%) were included. Histology was osteosarcoma (n = 20, 53%), Ewing sarcoma (n = 13, 34%) and chondrosarcoma (n = 5, 13%). Twelve patients (31.5%) had synchronous metastases, all received chemotherapy before PM. Median number of metastases was 3 (1 to 29). Twenty (53%) patients had mediastinal lymph node sampling. One patient had positive lymph nodes. Ninety-day mortality was 0%. Three and 5-year PFS were 24.5 and 21%, respectively. Three and 5-year OS were 64.5 and 38.5%, respectively. More than three metastases and progression under chemotherapy were significant independent predictors for OS.

Conclusion

PM is a safe procedure and encouraging long-term outcome can be achieved. Patients with progression of pulmonary metastases under chemotherapy as well as patients with more than three metastases had significantly worse OS.

Successive Osteosarcoma Relapses after the First Line O2006/Sarcome-09 Trial: What Can We Learn for Further Phase-II Trials?

Simple Summary

Osteosarcoma is the most common primary malignant bone tumour in adolescents and young adults. The survival of osteosarcoma patients has not improved for four decades. The purpose was to describe first and subsequent relapses in patients from the OS2006/Sarcome-09 trial, to help future trial design. Among the 434 patients with a confirmed osteosarcoma who achieved CR1 during first line treatment, 157 patients experienced at least one relapse. The 3-year progression-free and overall survival rates were 21% and 37%, respectively. Only a quarter of the patients were included in clinical trials at first recurrence. We want to promote randomised phase-II trials in osteosarcoma relapses, with broad inclusion criteria at study entry in terms of age and disease status, and PFS as primary endpoint. Surgery/local treatment of all residual lesions should be allowed when feasible. Single-arm trial design could be used for subsequent relapses.

Abstract

The purpose was to describe first and subsequent relapses in patients from the OS2006/Sarcome-09 trial, to help future trial design. We prospectively collected and analysed relapse data of all French patients included in the OS2006/Sarcome-09 trial, who had achieved a first complete remission. 157 patients experienced a first relapse. The median interval from diagnosis to relapse was 1.7 year (range 0.5–7.6). The first relapse was metastatic in 83% of patients, and disease was not measurable according to RECIST 1.1 criteria in 23%. Treatment consisted in systemic therapy (74%) and surgical resection (68%). A quarter of the patients were accrued in a phase-II clinical trial. A second complete remission was obtained for 79 patients. Most of them had undergone surgery (76/79). The 3-year progression-free and overall survival rates were 21% and 37%, respectively. In patients who achieved CR2, the 3y-PFS and OS rates were 39% and 62% respectively. Individual correlation between subsequent PFS durations was poor. For osteosarcoma relapses, we recommend randomised phase-II trials, open to patients from all age categories (children, adolescents, adults), not limited to patients with measurable disease (but stratified according to disease status), with PFS as primary endpoint, response rate and surgical CR as secondary endpoints.

Complete remission of metastatic osteosarcoma using combined modality therapy: a retrospective analysis of unselected patients in China

Background

Complete surgical remission (CSR) is the best predictor of overall survival (OS) for patients with metastatic osteosarcoma. However, metastasectomy has not been widely implemented in China in the last decade due to various factors, and instead, most physicians choose hypofractionated radiotherapy to treat pulmonary lesions. This study aimed to retrospectively evaluate the outcomes of different local treatments for pulmonary lesions and identify the best local therapy strategies for these patients.

Methods

We reviewed the clinical courses of osteosarcoma patients with pulmonary metastases who were initially treated in two sarcoma centres in Beijing, China, from June 1st, 2009, to March 26th, 2020. With a median follow-up of 32.4 (95% confidence interval (CI): 30.8, 36.1) months, a total of 127 patients with 605 pulmonary nodules, all of whom had received local therapy and firstly achieved CSR or complete radiated/metabolic remission (CRR), were included in the analysis. A total of 102 patients with 525 nodules were initially diagnosed with resectable lung metastases, while 25 patients had 80 indeterminate nodules at presentation and relapsed with pulmonary metastases within 6 months after the completion of adjuvant chemotherapy.

Results

Eighty-eight of 127 (69.3%) patients had fewer than 5 nodules at the time of local therapy, with 48 of 127 (37.8%) located in the unilateral pleura. No patient underwent thoracotomy, and 42 of 127 patients (85 nodules) received video-assisted thoracoscopic surgery (VATS). In addition, 79 of 127 patients (520 nodules) received hypofractionated stereotactic body radiotherapy (RT), such as Gamma Knife radiosurgery or CyberKnife radiosurgery. The twelve-month event-free survival (EFS) (from local therapy to progression) rate of this entire study cohort was 35.6% (95% CI: 26.8, 44.4%), without a significant difference between the two groups (44.7% for VATS vs. 28.4% for RT, P = 0.755). Radiation-induced pneumonitis was observed in 62 of 86 (72.1%) patients, with one patient (1/86, 1.2%) in grade 4.

Conclusions

Our past data showed a similar prognosis with the use of hypofractionated radiotherapy and VATS for the treatment of pulmonary metastasis and no inferiority to thoracotomy regarding historical outcomes. Currently, high-resolution chest computed tomography (CT) provides sufficient information on nodules, and less invasive modalities can thus be considered for treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08071-5.

Osteosarcoma Cell-Derived Exosomal miR-1307 Promotes Tumorgenesis via Targeting AGAP1

The occurrence of osteosarcoma (OS) is associated with abnormal expression of many microRNAs (miRNAs). Exosomal miRNAs get much more attentions in intracellular communications. miR-1307 has been studied in many cancers, but its effects in OS have not been studied. We hypothesized that OS-derived exosomal miR-1307 regulates OS tumorigenesis. First, we found OS cell-derived exosomes (Exos) significantly promoted the proliferation, migration, and invasion of OS cells. Secondly, we found miR-1307 was highly expressed in OS cell-derived exosomes (OS-Exos), human OS tissues, and OS cell lines. Then, OS-Exos were extracted after OS cells were cultured and transfected with miR-1307 inhibitor, and the level of miR-1307 in OS-Exos was significantly reduced. When the level of miR-1307 in OS-Exos was significantly reduced, the effects of OS-Exos on migration, invasion, and proliferation of OS cells were also significantly weakened. Furthermore, using TargetScan, miRDB, and mirDIP databases, we identified that AGAP1 was a target gene of miR-1307. Overexpression of miR-1307 could inhibit the expression of AGAP1 gene. We also found AGAP1 was lower expressed in human OS tissues and OS cell lines. Luciferase gene indicated that miR-1307 directly bound the 3'-UTR of AGAP1. miR-1307 was negatively correlated with AGAP1 in clinical study. miR-1307 could significantly promote the proliferation, migration, and invasion of OS cells. In addition, upregulation of AGAP1 could significantly inhibit the role of miR-1307 in OS. In conclusion, our study suggests that OS cell-derived exosomal miR-1307 promotes the proliferation, migration, and invasion of OS cells via targeting AGAP1, and miR-1307-AGAP1 axis may play an important role in the future treatment of OS.

Current surgical management of children with osteosarcoma and pulmonary metastatic disease: A survey of the American Pediatric Surgical Association

BACKGROUND

Rates of long-term survival for children with pulmonary metastatic osteosarcoma are low, and complete surgical resection of all visible pulmonary metastases is necessary for long term survival. Surgical approaches for metastasectomy include thoracotomy and thoracoscopy, with the approach chosen influenced by training and institutional bias. Thoracotomy with manual palpation of lung surfaces can identify nodules not seen on preoperative imaging, but no clear survival benefit has been demonstrated compared to complete thoracoscopic resection of all visible nodules.

METHODS

All member of the American Pediatric Surgical Association were surveyed, and 204 members responded.

RESULTS

Thoracoscopy was the preferred approach of 34% of surgeons for patients with 3 unilateral nodules but only 21% for those with 5 unilateral nodules. Hospital volume did not correlate with operative approach. Localization strategies are used by 37% of surgeons who prefer thoracotomy and 64% who prefer thoracoscopy. Importantly, the vast majority of responding surgeons (84%) expressed a willingness to participate in a randomized controlled trial of thoracotomy versus thoracoscopy.

CONCLUSION

Findings of this survey of North American pediatric surgeons confirm both the need for, and interest in, a prospective trial to define optimal surgical management of children with osteosarcoma with limited pulmonary metastasis.

LEVEL OF EVIDENCE

V.

Bio-analytical Identification of Key Genes that Could Contribute to the Progression and Metastasis of Osteosarcoma

Background:

Osteosarcoma (OS) is one of the most common primary malignant bone tumors in children and adolescents. OS metastasis has been a challenge in the treatment of OS. The present study screened progression related genes in OS by analyzing a public dataset GSE42352, and identified 691 up-regulated and 945 down-regulated genes in advanced stage OS compared to early-stage OS samples.

Methods:

Protein-protein interaction (PPI) networks were further employed to reveal the interaction among these genes. Bioinformatics analysis showed that progression related differently expressed genes (DEGs) were significantly associated with the regulation of cell proliferation and metabolisms.

Results:

This study revealed that progression related DEGs were dysregulated in metastatic OS compared to non-metastatic OS samples. Further analysis showed CSF1R, CASP1, CD163, AP1B1, LAPTM5, PEX19, SLA, STAB1, YWHAH, PLCB2, and GPR84 were associated with the metastasis-free survival time in patients with OS.

Conclusions:

These findings provided novel information for us to understand the mechanisms underlying the progression and metastasis of OS.

Phase I/II Study of Stereotactic Body Radiation Therapy for Pulmonary Metastases in Pediatric Patients

Purpose

Pulmonary metastases are common in many pediatric solid tumors; however, little is known about safety and efficacy of lung stereotactic body radiation therapy (SBRT) for pediatric patients. We conducted a phase I/II study to investigate the minimum effective dose level of SBRT with an acceptable safety profile in pediatric patients.

Methods and Materials

Patients with sarcoma and metastatic pulmonary lesions ≤3 cm in diameter and ≤21 years of age were enrolled. Dose levels 1, 2, and 3 were 24, 30, and 36 Gy in 3 fractions, respectively. Enrolled patients with metastases from primary renal tumors and sarcoma histologies were to begin at dose level 1 and 2, respectively. Exclusion criteria included receipt of whole-lung/hemi-thorax irradiation >12 Gy within 6 months of consent. Primary endpoints were tolerability and safety per Common Terminology Criteria for Adverse Events grading and disease response at 6 weeks post-SBRT per response evaluation criteria in solid tumors (RECIST) 1.1 criteria. Secondary endpoints included rates of local control and distant failure within the lung, but outside of the treatment volume.

Results

Five patients with median age of 13 years (range, 7-21) received SBRT at dose level 2. Primary tumor histologies included Ewing sarcoma (n = 3), anaplastic chordoma (n = 1), and osteosarcoma (n = 1). No grade ≥3 adverse events were observed. At 6 weeks after SBRT, 7/8 (87.5%) lesions achieved partial response. With median follow-up of 2.1 years (range, 1.4-2.5), 2-year local control and distant failure-free survival were 60% (n = 8) and 40% (n = 5), respectively. One patient developed widespread metastases and succumbed to disease 1.4 years after SBRT.

Conclusions

SBRT for pulmonary metastases produces responses in pediatric patients with sarcoma at 6 weeks with acceptable toxicity; however, patients remain at risk of local and distant failure within the lung. Future prospective studies are needed to investigate whether higher doses of SBRT, possibly in combination with other therapies, are safe and provide more durable response.

Survival after pulmonary metastasectomy for relapsed osteosarcoma

OBJECTIVES

The purpose of this study was to evaluate the postrelapse survival of relapsed osteosarcoma with pulmonary metastases in patients who received pulmonary metastasectomy using intent to treat and propensity score analysis.

METHODS

Patients with osteosarcoma who relapsed with pulmonary metastases between 2004 and 2018 who were treated in a hospital affiliated with a medical school were included. All the enrolled patients were evaluated as operable with assessment algorithm at the time of diagnosis of pulmonary relapse and intent to treat analysis was done. Multiple propensity score methods (eg, matching, stratification, covariate adjustment, and inverse probability of treatment weighting) were performed to balance confounding bias. Cox proportional hazards regression and the Kaplan-Meier method were used to evaluate patient survival.

RESULTS

A total of 125 patients met the study criteria. Of these, 59 (47.2%) patients received pulmonary metastasectomy combined with chemotherapy and 66 (52.8%) received chemotherapy alone. The 2-year and 5-year postrelapse survival rate of metastasectomy group and nonmetastasectomy group were 68.4% versus 25.0% and 41.0% versus 0%, respectively. The median postrelapse survival was 24.9 versus 13.5 months, respectively. Pulmonary metastasectomy was independently associated with improved survival (hazard ratio, 0.185; 95% confidence interval, 0.103-0.330; P < .001). These results were confirmed by multiple propensity score analyses. Further stratified analysis revealed that the survival advantage associated with metastasectomy was not significant in patients with metastases involving ≥3 lung lobes and patients with very high pretreatment serum alkaline phosphatase (more than twice the upper limit).

CONCLUSIONS

Pulmonary metastasectomy is associated with improved survival in patients with recurrent osteosarcoma.

Hip transposition procedure due to osteosarcoma metastasis of the ilium in a patient with preexisting rotationplasty leads to satisfactory functional result: A case report

•

Hemipelvectomy (PI-II) after rotationplasty on the same leg resulted in a good functional result in a 16 year old male patient with osteosarcoma.

•

For hemipelvectomy, the musculus gluteus maximus is essential for soft tissue coverage, therefore supplying structures must be preserved.

•

The triradiate cartilage of the acetabulum closes around a bone age of 12 years in boys and then is no sufficient barrier for an osteosarcoma.

Introduction

The hip transposition is a limb salvage procedure for periacetabular malignancies. Here we present the case of a patient that already had a preexisting ipsilateral rotationplasty.

Presentation of case

A 16 year old male patient with an Osteosarcoma of the left distal femur was treated with wide surgical resection of the tumor and rotationplasty (Salzer/Winkelmann type A1). Despite adjuvant chemotherapy (EURAMOS protocol) he was diagnosed with metachronous metastases in the lung and in the left ilium affecting the acetabulum. As a limb salvage procedure the patient received an internal hemipelvectomy Enneking PI-II and an attachment of the femoral head with a Trevira tube to the sacrum using suture anchors. After six weeks a prosthesis was fitted and gradually full weight bearing was allowed. The patient achieved a good functional result as he was able to walk freely for three more years before he passed away.

Discussion

The hip transposition procedure does not require the implantation of a large tumor prosthesis and thus avoids the problem of an increased risk of infection. Even with preexisting ipsilateral rotationplasty a good functional outcome that allowed the patient full weight bearing could be achieved.

Conclusion

If there are already existing deformities, such as rotationplasty on the same leg, the hip transposition procedure can be considered for periacetabular malignancies, as it can achieve satisfactory results.

Popliteal lymph nodes in patients with osteosarcoma: are they metastatic?

PURPOSE

To evaluate the prevalence, imaging appearance, and significance of popliteal lymph nodes (PLN) on magnetic resonance imaging (MRI) in patients with distal femoral or proximal tibial osteosarcoma (OS).

METHOD AND MATERIALS

This study included consecutive patients with OS presenting from May 2016 to March 2018. Inclusion criteria were patients with distal femoral or proximal tibial OS with MRI and pathology at our institution. On MRI, two radiologists recorded primary tumor features (size, location, signal, extra-compartmental extension), and PLN characteristics (mean size, presence/absence of fatty hilum, mineralization, PET/bone scintigraphy avidity, contrast enhancement, and diffusion restriction). Tumor histology, stage, and clinical follow-up were recorded. Descriptive statistics were provided.

RESULTS

Sixteen patients with OS (age 20 ± 10 (range10-40) years, 10/16 male) were included. Although 81% (13/16) of the patients had PLNs at presentation (size range 0.3-3.6 cm), fewer patients had extra-compartmental spread: intra-articular extension 50% (8/16), skip lesions 19% (3/16), lung metastases 31% (5/16), and osseous metastases 12% (2/16). Four (25% (4/16)) patients had PLN ≥ 1 cm; two were histologically proven reactive. One was presumed metastatic due to rapid development, mineralization, and FDG-avidity on PET/CT. The other ≥ 1 cm PLNs along with all twelve (75% (12/16)) that were < 1 cm in mean diameter were presumed non-metastatic with documented stability for at least 12 months of follow-up.

CONCLUSION

PLNs are frequently visible on MRI in patients with OS but are rarely (prevalence = 6%) metastatic. Features on MRI which may suggest metastatic PLNs include large size > 1 cm and loss of a fatty hilum.

Role of Platelet C-Type Lectin-Like Receptor 2 in Promoting Lung Metastasis in Osteosarcoma

The overall prognosis of patients with sarcoma-based cancers has changed little in the last 20 years. There is an urgent need to investigate the metastatic potential of these tumors and to develop anti-metastatic drugs. It is becoming increasingly clear that platelets play an important role in the establishment of metastasis of carcinoma cells and could be a useful therapeutic target for patients with carcinoma. However, little is known about the role of platelets in sarcoma progression. Here, we investigated how osteosarcoma progression relates to platelet function to explore the possibility of anti-platelet therapy. We found that, similar to carcinoma cells, podoplanin (also known as Aggrus)-positive osteosarcoma cells induce platelet aggregation and activation. Administration of anti-glycoprotein Ibα (GPIbα, also known as CD42b) antibody reduced the lung metastasis of osteosarcoma. The supernatant from platelets cocultured with osteosarcoma cells contained several growth factors and promoted proliferation, invasiveness, and sphere formation of osteosarcoma cells in vitro. In addition, the development of lung metastasis was highly dependent on direct interaction between osteosarcoma cells and platelets. To explore the therapeutic target, we focused on the interactions between podoplanin on osteosarcoma and C-type lectin-like receptor (CLEC)-2 on platelets. The administration of a depleting antibody against CLEC-2 efficiently suppressed osteosarcoma metastasis into the lung. We also analyzed clinical data from patient samples at primary and metastatic sites. Although GPIbα expression was similar between the two sites, there was a significant increase in podoplanin at the metastatic site compared to that in the primary site, and the level of podoplanin expression in the primary site correlated with patient prognosis. These findings suggest that blockade of interactions between platelets CLEC-2 and osteosarcoma podoplanin represent the most promising therapeutic strategy for preventing the lung metastasis of osteosarcoma. © 2020 American Society for Bone and Mineral Research.

Clinical factors affecting prognosis of limb osteosarcoma in China: a multicenter retrospective analysis

Objective

This study was performed to explore the relationship between various clinical factors and the prognosis of limb osteosarcoma.

Methods

We retrospectively analyzed the clinical data of 336 patients with limb osteosarcoma treated from June 2000 to August 2016 at 7 Chinese cancer centers. Data on the patients’ clinical condition, treatment method, complications, recurrences, metastasis, and prognosis were collected and analyzed. Kaplan–Meier analysis and Cox regression models were used to analyze the data.

Results

The patients comprised 204 males and 132 females ranging in age from 6 to 74 years (average, 21.1 years). The overall 3- and 5-year survival rates were 65.0% and 55.0%, respectively. The 5-year overall survival rate was 64.0% with standard chemotherapy and 45.6% with non-standard chemotherapy. Cox regression analysis demonstrated that standard chemotherapy, surgery, recurrence, and metastasis were independent factors associated with the prognosis of limb osteosarcoma.

Conclusion

The survival of patients with limb osteosarcoma can be significantly improved by combining standard chemotherapy and surgery. The overall survival rate can also be improved by adding methotrexate to doxorubicin–cisplatin–ifosfamide triple chemotherapy.

Thoracoscopy vs thoracotomy for the management of metastatic osteosarcoma: A Pediatric Surgical Oncology Research Collaborative Study

Complete surgical resection of pulmonary metastatic disease in patients with osteosarcoma is crucial to long-term survival. Open thoracotomy allows palpation of nodules not identified on imaging but the impact on survival is unknown. The objective of this study was to compare overall survival (OS) and pulmonary disease-free survival (DFS) in children who underwent thoracotomy vs thoracoscopic surgery for pulmonary metastasectomy. A multi-institutional collaborative group retrospectively reviewed 202 pediatric patients with osteosarcoma who underwent pulmonary metastasectomy by thoracotomy (n = 154) or thoracoscopy (n = 48). Results were analyzed by Kaplan-Meier survival estimates and multivariate Cox proportional hazard regression models. With median follow-up of 45 months, 135 (67.5%) patients had a pulmonary relapse and 95 (47%) patients were deceased. Kaplan-Meier analysis showed no significant difference in 5-year pulmonary DFS (25% vs 38%; P = .18) or OS (49% vs 42%, P = .37) between the surgical approaches of thoracotomy and thoracoscopy. In Cox regression analysis controlling for other factors impacting outcome, there was a significantly increased risk of mortality (HR 2.11; P = .027; 95% CI 1.09-4.09) but not pulmonary recurrence (HR 0.96; P = .90; 95% CI 0.52-1.79) with a thoracoscopic approach. However, in the subset analysis limited to patients with oligometastatic disease, thoracoscopy had no increased risk of mortality (HR 1.16; P = .62; 0.64-2.11). In conclusion, patients with metastatic osteosarcoma and limited pulmonary disease burden demonstrate comparable outcomes after thoracotomy and thoracoscopy for metastasectomy. While significant selection bias in these surgical cohorts limits the generalizability of the conclusions, clinical equipoise for a randomized clinical trial in patients with oligometastatic disease is supported.

Increased DEF6 expression is correlated with metastasis and poor prognosis in human osteosarcoma

Metastasis is the primary cause of high mortality in patients with osteosarcoma (OS). However, the molecular mechanisms underlying the regulation of metastatic disease are yet to be determined. Differentially expressed in FDCP 6 homolog (DEF6) has been demonstrated to be correlated with the metastatic behavior of several cancers, such as breast, ovarian and colorectal cancers. However, the role of DEF6 in OS remains unknown. Accordingly, the current study aimed to investigate the relationship between DEF6 expression and the malignant behavior of OS. The results revealed that high levels of DEF6 in OS tissues were associated with advanced clinical stage and metastases. Furthermore, immunohistochemistry results predicted a poor prognosis in 58 human OS specimens. Additionally, DEF6 expression was reported to be upregulated in human OS cell lines compared with a normal osteoblast cell line. small interfering RNA transfection, cell proliferation and colony formation assays, wound healing assays and Transwell assays were performed. DEF6 was not identified to be a major driver of OS cell proliferation, but it significantly contributed to metastatic potential in vitro. In addition, bioinformatics, western blotting and immunohistochemistry results indicated that MMP9 expression was positively correlated with DEF6 expression in human OS. To summarize, the results revealed that increased levels of DEF6 were associated with metastasis and poor prognosis in human OS and that DEF6 expression is positively correlated with MMP9 expression. The results indicated that DEF6 may serve as a potential antimetastatic target for OS.

Management of Refractory Pediatric Sarcoma: Current Challenges and Future Prospects

Paediatric sarcomas are a heterogeneous group of disorders constituting bone sarcoma and various soft tissue sarcomas. Almost one-third of these presents with metastasis at baseline and another one-third recur after initial curative treatment. There is a huge unmet need in this cohort in terms of curative options and/or prolongation of survival. In this review, we have discussed the current treatment options, challenges and future strategies of managing relapsed/refractory paediatric sarcomas. Upfront risk-adapted treatment with multidisciplinary management remains the main strategy to prevent future recurrence or relapse of the disease. In the case of limited local and/or systemic relapse or late relapse, initial multimodality management can be administered. In treatment-refractory cases or where cure is not feasible, the treatment options are limited to novel therapeutics, immunotherapeutic approach, targeted therapies, and metronomic therapies. A better understanding of disease biology, mechanism of treatment refractoriness, identifications of driver mutation, the discovery of novel targeted therapies, cellular vaccine and adapted therapies should be explored in relapsed/refractory cases. Close national and international collaboration for translation research is needed to fulfil the unmet need.

What is the best clinical approach to recurrent/refractory osteosarcoma?

Introduction: Osteosarcoma is the most common malignant bone tumor. It is currently treated with pre-and postoperative chemotherapy, associated with surgical resection of the tumor.Area covered: Relapses occur in about one in three patients presenting with localized disease, and three in four of those with metastases at diagnosis. Relapsing disease carries a very poor prognosis, with 5-year survival rates ranging between 13% and 40%.Expert opinion: Patients with unilateral lung involvement or solitary lung metastases and a recurrence-free interval (RFI) longer than 24 months have a better prognosis, and could be managed with surgical resection and close observation. Complete surgical resection of all sites of disease remains essential to survival: patients unable to achieve complete remission have a catastrophic overall survival rate. The role of second-line chemotherapy is not at all clear, and no controlled studies are available on this topic. It is worth considering for patients unable to achieve complete surgical remission, and those with multiple metastases and/or a RFI <24 months. Given their dismal prognosis, patients with multiple sites of disease not amenable to complete surgical resection should also be considered for innovative therapeutic approaches.

Long-Term Follow-up of a Randomized Study of Oral Etoposide versus Viscum album Fermentatum Pini as Maintenance Therapy in Osteosarcoma Patients in Complete Surgical Remission after Second Relapse

BACKGROUND

In relapsed osteosarcoma, the 5-yr postrelapse disease-free survival (PRDFS) rate after the second relapse is <20%. In June 2007, a randomized study was started comparing oral etoposide vs Viscum album fermentatum Pini (an extract derived from the parasitic plant Viscum album L., European mistletoe) as maintenance therapy in patients with metastatic osteosarcoma in complete surgical remission after the second relapse. The primary endpoint was the PRDFS rate at 12 months (compared to the historical control rate). This is a long-term updated result. Patients and Methods. 10 patients received oral etoposide 50 mg/m2 daily for 21 days every 28 days for 6 months, and 9 patients received Viscum album fermentatum Pini 3 times/wk subcutaneously for 1 year. The study closed early in July 2011 due to insufficient recruitment. Lymphocyte subpopulations were analyzed at T0, T3, T6, T9, and T12 months.

RESULTS

On 30 June 2019, at a median follow-up ITT of 83 months (range 3-144 ms), a median PRDFS of 106 ms (2-144) was observed in the Viscum arm with 5/9 patients who never relapse vs a PRDFS of 7 months (3-134) in the etoposide arm (all patients in the Etoposide arm relapsed) (hazard ratio HR = 0.287, 95% CI: 0.076-0.884, p=0.03). Model forecast 10-yr overall survival rates as 64% in the Viscum arm and 33% in the etoposide arm. Lymphocyte subpopulation counts (CD3, CD4, and CD56) showed an increase in the Viscum arm while a decrease was observed in the etoposide arm during treatment.

CONCLUSIONS

After 12 years from the start of the trial, the patients in the Viscum arm continue to show a considerably longer PRDFS compared to oral etoposide, and a trend for an advantage in OS is evident even if the number of treated patients is too small to draw conclusions. Viscum as maintenance treatment after complete surgical remission in relapsed osteosarcoma should be further investigated and compared with other drugs.

Long Non-Coding RNA FEZF1-AS1 Modulates CXCR4 to Promote Cell Proliferation, Warburg Effect and Suppress Cell Apoptosis in Osteosarcoma by Sponging miR-144

BACKGROUND

Osteosarcoma (OS) is a common bone tumor among children, adolescents, and young adults. Long non-coding RNA (lncRNA) FEZF1 antisense RNA 1 (FEZF1-AS1) has been reported as an oncogene in diverse tumors including colorectal cancer, pancreatic cancer and hepatocellular carcinoma, as well as in osteosarcoma. This study focused on the functions and mechanism of lncRNA FEZF1-AS1 in osteosarcoma.

METHODS

The levels of FEZF1-AS1, microRNA miR-144 and CXC motif chemokine receptor 4 (CXCR4) in OS tissues and cells (Saos-2 and HOS) were measured by quantitative real-time polymerase chain reaction (qRT-PCR) or Western blot assay. The interactions between miR-144 and FEZF1-AS1 or CXCR4 were predicted by DIANA tools online database. Then, the dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were conducted to validate the interactions. Moreover, the cell viability and apoptotic rate in transferred Saos-2 and HOS cells were assessed via 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay and flow cytometry, respectively. The levels of glucose and lactate productions were measured by glucose uptake and lactate production assay. In addition, the protein levels of Warburg-effect-related protein hexokinase 2 (HK2) and apoptosis-related proteins Bcl-2 or Bax in transferred Saos-2 and HOS cells were detected via Western blot assay.

RESULTS

The levels of FEZF1-AS1 and CXCR4 were strikingly up-regulated, and miR-144 was notably down-regulated in OS tissues and cells. DIANA tools online database exhibited that miR-144 was a direct target of FEZF1-AS1 and CXCR4 was a direct target of miR-144. Then the interactions were validated by dual-luciferase reporter assay and RIP assay. Functionally, FEZF1-AS1 silencing or miR-144 overexpression inhibited cell viability, the glucose and lactate productions and promoted cell apoptosis in Saos-2 and HOS cells. Furthermore, miR-144 inhibitor mitigated the inhibitory effects on cell viability, the glucose and lactate productions and the promoted effect on cell apoptosis rate in Saos-2 and HOS cells induced by FEZF1-AS1 depletion. Mechanistically, FEZF1-AS1 regulated CXCR4 in Saos-2 and HOS cells by sponging miR-144.

CONCLUSION

We verified that FEZF1-AS1, CXCR4 were up-regulated, and miR-144 was downregulated in OS tissues and cells. Furthermore, FEZF1-AS1 promoted cell proliferation, Warburg effect and suppressed cell apoptosis in osteosarcoma via miR-144/CXCR4 axis, this novel pathway may provide a basis for the further study of osteosarcoma.

A population-based propensity-matched study of regional dissections in patients with metastatic osteosarcoma

Background

The survival rates of patients with metastatic osteosarcoma are poor, and the prognosis is closely related to the choice of treatment, especially surgery. This study aimed to evaluate the survival outcomes of patients with metastatic osteosarcoma undergoing regional dissections.

Methods

We collected data on patients with metastatic osteosarcoma between 2004 and 2014 from the Surveillance, Epidemiology, and End Results (SEER) database. Kaplan–Meier curves were used to compare overall survival (OS) and cancer-specific survival (CSS), while univariate and multivariate Cox regression analyses were used to evaluate outcomes. Propensity score matching (PSM) was used to minimize the effects of confounding factors.

Results

The SEER database had records of 2768 patients diagnosed with osteosarcoma, of whom 398 were included in our study. Of the included patients, 116 (29.15%) underwent regional dissections, while 282 (70.85%) underwent non-regional dissections. The univariate and multivariate Cox regression analyses, prior to PSM, showed that OS (hazard ratio (HR): 0.34, 95% confidence interval (CI): 0.26–0.44, P<0.001 and HR: 0.47, 95% CI: 0.35–0.64, P<0.001, respectively) and CSS (HR: 0.33, 95% CI: 0.25–0.43, P<0.001 and HR: 0.46, 95% CI: 0.34–0.63, P<0.001, respectively) were better in patients who underwent regional dissections than those who underwent non-regional dissections. Compared with non-regional dissections, regional dissections, which included both primary tumour resection (PTR) and primary tumour and metastatic site resection (PTMR), were associated with better OS (P<0.001) and CSS (P<0.001) . However, the survival outcomes following PTR and PTMR showed no significant difference. After PSM, patients in the regional dissection group still had a higher OS (P<0.001) and CSS (P<0.001) than those in the non-regional dissection group.

Conclusions

Compared with non-regional dissection, regional dissection resulted in better survival in patients with metastatic osteosarcoma.

CXCL1/CXCR2 Paracrine Axis Contributes to Lung Metastasis in Osteosarcoma

Osteosarcoma, the most common of all bone malignancies, has a high likelihood of lung metastasis. Up until now, the molecular mechanisms involved in osteosarcomas with lung metastases are not clearly understood. Recent observations have shown that the chemokine CXCL1 and its receptor CXCR2 assist with the homing of neutrophils into the tumor microenvironment. Here, we show that the CXCL1/CXCR2 paracrine axis is crucial for lung metastasis in osteosarcoma. In an in vivo lung metastasis model of osteosarcoma, lung blood vessels expressed CXCL1 and osteosarcoma cells expressed the CXCR2 receptor. CXCR2 expression was higher in osteosarcoma cell lines than in normal osteoblast cells. Immunohistochemistry staining of clinical osteosarcoma specimens revealed positive correlations between CXCR2 expression and pathology stage and also vascular cell adhesion molecule 1 (VCAM-1) expression. High levels of CXCL1 secreted by human pulmonary artery endothelial cells (HPAECs) promoted osteosarcoma cell mobility, which was mediated by the upregulation of VCAM-1 expression. When HPAECs-conditioned media was incubated in osteosarcoma cells, we observed that the CXCR2 receptor and FAK/PI₃K/Akt/NF-κB signaling cascade were required for VCAM-1 expression. Our findings illustrate a molecular mechanism of lung metastasis in osteosarcoma and indicate that CXCL1/CXCR2 is worth targeting in treatment schemas.

Silencing METTL3 inhibits the proliferation and invasion of osteosarcoma by regulating ATAD2

BACKGROUND

Osteosarcoma is the most common primary malignant bone tumor in children and young adults. RNA N⁶-methyladenosine (m⁶A) is the most abundant internal modification in mammalian mRNA, which is involved in tumorigenesis and tumor progression. It has been reported that methyltransferase-like 3 (METTL3), the first reported m6A "writer", plays critical roles in cancer progression. However, its role and molecular mechanism in osteosarcoma is poor studied. In this study, we aimed to investigate the functional role and underlying mechanism of METTL3 in the progression of osteosarcoma.

METHODS

We detected the mRNA expression of METTL3 in osteosarcoma cell lines, and immunofluorescence assay was performed to observe the location of METTL3. Cell lines with METTL3 gene overexpression or knockdown were established by pcDNA3.1-METTL3 or siRNA interferences in order to determine the function of METTL3 in osteosarcoma in vitro. Transcriptomic RNA sequencing (RNA-seq) were used to screen the target genes of METTL3 in osteosarcoma.

RESULTS

We found that METTL3 localized in cytoplasm and nucleus of osteosarcoma cells. Silencing METTL3 in SAOS-2 and MG63 cells significantly inhibited the m⁶A methylation level, proliferation, migration, and invasion abilities, as well as promoted cell apoptosis. However, up-regulation of METTL3 had no significant effect on the biological behaviors of U2OS cells. Further mechanism analysis suggested that METTL3 knockdown inhibited the expression of ATPase family AAA domain containing 2 (ATAD2). Moreover, ATAD2 knockdown inhibited the proliferation and invasion of SAOS-2 and MG63 cells, while its overexpression showed a significant increase in cell proliferation and invasion. Furthermore, METTL3 knockdown abrogated the promoting effects of ATAD2 overexpression on osteosarcoma cells proliferation and invasion.

CONCLUSION

Overall, our study revealed that METTL3 functions as an oncogene in the growth and invasion of osteosarcoma by regulating ATAD2, suggesting a potential therapeutic target for osteosarcoma treatment.

Long-term follow-up in adults with extremity osteosarcoma: comparison of different surgical procedures - single-center experience

Introduction

Osteosarcoma is the most common primary malignant bone tumor in adults and is usually located in long bones. Standard treatment consists of perioperative chemotherapy and radical surgical resection. In the case of the extremity location, the gold standard is limb-sparing surgery (LSS) using a variety of reconstructive techniques.

Aim of the study

To assess long-term results of adults patients treated for limb osteosarcoma in our referral center depending on the method of surgical treatment.

Material and methods

In our study, we analyzed 175 adult patients with localized disease (American Joint Committee on Cancer [AJCC] stage I-III) treated for extremity osteosarcoma at our institution between 2000 and 2017. The median observation time was 41 months (3-225 months). 111 patients were treated with LSS (80 patients had tumor resection followed by endoprosthetic reconstruction, 31 patients had local resection without reconstruction) and 64 patients underwent amputation.

Results

5-year overall survival (OS) and progression-free survival (PFS) in the study group were 62% and 52% and the life expectancy was on average 136 months. In the group of patients treated with LSS, 5-year OS and PFS were 66% and 59%, respectively, and life expectancy was 147 months, while in the group of patients undergoing amputation 5-year OS, PFS and life expectancy were 55%, 42% and 117 months.

Conclusions

The best results in the treatment of extremity osteosarcoma were achieved in a group of patients without distant metastases at the time of diagnosis, treated with perioperative chemotherapy and radical resection followed by endoprosthetic reconstruction.