Improvement in histologic response but not survival in osteosarcoma patients treated with intensified chemotherapy: a randomized phase III trial of the European Osteosarcoma Intergroup

Exosomal mRNA Cargo are biomarkers of tumor and immune cell populations in pediatric osteosarcoma

Osteosarcoma is the commonest malignant bone tumor of children and adolescents and is characterized by a high risk of recurrence despite multimodal therapy, especially in metastatic disease. This suggests the presence of clinically undetected cancer cells that persist, leading to cancer recurrence. We sought to evaluate the utility of peripheral blood exosomes as a more sensitive yet minimally invasive blood test that could aid in evaluating treatment response and surveillance for potential disease recurrence. We extracted exosomes from the blood of pediatric osteosarcoma patients at diagnosis (n=7) and after neoadjuvant chemotherapy (n=5 subset), as well as from age-matched cancer-free controls (n=3). We also obtained matched tumor biopsy samples (n=7) from the cases. Exosome isolation was verified by CD9 immunoblot and characterized on electron microscopy. Profiles of 780 cancer-related transcripts were analysed in mRNA from exosomes of osteosarcoma patients at diagnosis and control patients, matched post-chemotherapy samples, and matched primary tumor samples. Peripheral blood exosomes of osteosarcoma patients at diagnosis were significantly smaller than those of controls and overexpressed extracellular matrix protein gene THBS1 and B cell markers MS4A1 and TCL1A. Immunohistochemical staining of corresponding tumor samples verified the expression of THBS1 on tumor cells and osteoid matrix, and its persistence in a treatment-refractory patient, as well as the B cell origin of the latter. These hold potential as liquid biopsy biomarkers of disease burden and host immune response in osteosarcoma. Our findings suggest that exosomes may provide novel and clinically-important insights into the pathophysiology of cancers such as osteosarcoma.

Age-dependent molecular variations in osteosarcoma: implications for precision oncology across pediatric, adolescent, and adult patients

Background

Osteosarcoma is a leading subtype of bone tumor affecting adolescents and adults. Comparative molecular characterization among different age groups, especially in pediatric, adolescents and adults, is scarce.

Methods

We collected samples from 194 osteosarcoma patients, encompassing pediatric, adolescent, and adult cohorts. Genomic analyses were conducted to reveal prevalent mutations and compare molecular features in pediatric, adolescent, and adult patients.

Results

Samples from 194 osteosarcoma patients across pediatric to adult ages were analyzed, revealing key mutations such as TP53, FLCN, NCOR1, and others. Children and adolescents showed more gene amplifications and HRD mutations, while adults had a greater Tumor Mutational Burden (TMB). Mutations in those over 15 were mainly in cell cycle and PI3K/mTOR pathways, while under 15s had more in cell cycle and angiogenesis with higher VEGFA, CCND3, TFEB mutations. CNV patterns varied with age: VEGFA and XPO5 amplifications more in under 25s, and CDKN2A/B deletions in over 25s. Genetic alterations in genes like MCL1 and MYC were associated with poor prognosis, with VEGFA mutations also indicating worse outcomes. 58% of patients had actionable mutations, suggesting opportunities for targeted therapies. Age-specific patterns were observed, with Multi-TKI mutations more common in younger patients and CDK4/6 inhibitor mutations in adults, highlighting the need for personalized treatment approaches in osteosarcoma. In a small group of patients with VEGFR amplification, postoperative treatment with multi-kinase inhibitors resulted in a PR in 3 of 13 cases, especially in patients under 15. A significant case involved a 13-year-old with a notable tumor size reduction achieving PR, even with other genetic alterations present in some patients with PD.

Conclusion

This study delineates the molecular differences among pediatric, adolescent, and adult osteosarcoma patients at the genomic level, emphasizing the necessity for precision diagnostics and treatment strategies, and may offer novel prognostic biomarkers for patients with osteosarcoma. These findings provide a significant scientific foundation for the development of individualized treatment approaches tailored to patients of different age groups.

Cell Cycle Checkpoints p16 and p21-Strong Predictors of Clinicopathologic Outcomes in High-Grade Osteosarcoma

PURPOSE

In this study, we used a series of immunohistochemical measurements of 2 cell cycle regulators, p16 and p21, to evaluate their prognostic value, separately and in combination, for the disease outcomes.

METHOD

A total of 101 patients with high-grade osteosarcoma were included in this study. Clinicopathologic data were collected, and immunohistochemistry for p16 and p21 was performed and interpreted by 3 independent pathologists. Statistical analysis was performed to assess the strength of each of these markers relative to disease outcome.

RESULTS

Our results indicate that more than 90% expression (high) of p16 by immunohistochemistry on the initial biopsy has a strong predictive value for good histologic response to chemotherapy. The patients are also more likely to survive the past 5 years and less likely to develop metastasis than patients with less than 90% p16 (low) expression. The results for p21, on the other hand, show a unique pattern of relationship to the clinicopathologic outcomes of the disease. Patients with less than 1% (low) or more than 50% (high) expression of p21 by immunohistochemistry show a higher chance of metastasis, poor necrotic response to chemotherapy, and an overall decreased survival rate when compared with p21 expression between 1% and 50% (moderate). Our results also showed that the expression of p16 and combined p16 and p21 demonstrates a stronger predictive relationship to 5-year survival than tumor histologic necrosis and p21 alone.

DISCUSSION

The results of this study, once proven to be reproducible by a larger number of patients, will be valuable in the initial assessment and risk stratification of the patients for treatment and possibly the clinical trials.

Viable tumor cell density after neoadjuvant chemotherapy assessed using deep learning model reflects the prognosis of osteosarcoma

Prognosis after neoadjuvant chemotherapy (NAC) for osteosarcoma is generally predicted using manual necrosis-rate assessments; however, necrosis rates obtained in these assessments are not reproducible and do not adequately reflect individual cell responses. We aimed to investigate whether viable tumor cell density assessed using a deep-learning model (DLM) reflects the prognosis of osteosarcoma. Seventy-one patients were included in this study. Initially, the DLM was trained to detect viable tumor cells, following which it calculated their density. Patients were stratified into high and low-viable tumor cell density groups based on DLM measurements, and survival analysis was performed to evaluate disease-specific survival and metastasis-free survival (DSS and MFS). The high viable tumor cell density group exhibited worse DSS (p = 0.023) and MFS (p = 0.033). DLM-evaluated viable density showed correct stratification of prognosis groups. Therefore, this evaluation method may enable precise stratification of the prognosis in osteosarcoma patients treated with NAC.

Significance of the Pretreatment Neutrophil-to-Lymphocyte and Platelet-to-Lymphocyte Ratios in Predicting the Response to Neoadjuvant Chemotherapy and Survival Rates in Extremity Osteosarcoma: A Multicentre Prospective Study

OBJECTIVES

We aimed to assess the effects of pretreatment neutrophil-to-lymphocyte and platelet-to-lymphocyte ratios on the response to neoadjuvant chemotherapy and survival rates in patients with extremity osteosarcoma.

PATIENTS AND METHODS

Patients with high-grade osteosarcoma admitted to oncologic centers affiliated with Iran University of Medical Sciences, Tehran, Iran from 2015 to 2021 were evaluated retrospectively to assess the impact of complete blood count-related parameters on the pathologic response after neoadjuvant chemotherapy. Then, patients were followed up prospectively to evaluate the survival rates. All patients received at least three cycles of cisplatin/doxorubicin regimen, preoperatively. In this study, the cut-off values for high neutrophil-to-lymphocyte and high platelet-to-lymphocyte ratio were considered 3.28 and 128, respectively.

RESULTS

One hundred eighty-six patients were enrolled. Patients with high neutrophil-to-lymphocyte ratio and high platelet-to-lymphocyte ratio had a significantly lower overall survival rates (20.7 [95% CI 18-23.5] month vs. 34.6 [95% CI 33.2-36], p = 0.003 and 21.9 [95% CI 20.2-23.6] month versus 35.3 [95% CI 33.9-36.7], p = 0.002; respectively). Moreover, disease-free survival of patients with high platelet-to-lymphocyte ratio was worse than patients with low platelet-to-lymphocyte ratio (20.4 [95% CI 18.4-22.4] month vs. 32.7 [95% CI 30.8-34.7], p = 0.02).

CONCLUSION

Our study showed that neutrophil-to-lymphocyte and platelet-to-lymphocyte ratios at the baseline can predict the survival of patients with high-grade osteosarcoma.

New gene signature from the dominant infiltration immune cell type in osteosarcoma predicts overall survival

The immune microenvironment of osteosarcoma (OS) has been reported to play an important role in disease progression and prognosis. However, owing to tumor heterogeneity, it is not ideal to predict OS prognosis by examining only infiltrating immune cells. This work aimed to build a prognostic gene signature based on similarities in the immune microenvironments of OS patients. Public datasets were used to examine the correlated genes, and the most consistent dominant infiltrating immune cell type was identified. The LASSO Cox regression model was used to establish a multiple-gene risk prediction signature. A nine-gene prognostic signature was generated from the correlated genes for M0 macrophages and then proven to be effective and reliable in validation cohorts. Signature comparison indicated the priority of the signature. Multivariate Cox regression models indicated that the signature risk score is an independent prognostic factor for OS patients regardless of the Huvos grade in all datasets. In addition, the results of the association between the signature risk score and chemotherapy sensitivity also showed that there was no significant difference in the sensitivity of any drugs between the low- and high-risk groups. A GSEA of GO and KEGG pathways found that antigen processing- and presentation-related biological functions and olfactory transduction receptor signaling pathways have important roles in signature functioning. Our findings showed that M0 macrophages were the dominant infiltrating immune cell type in OS and that the new gene signature is a promising prognostic model for OS patients.

Chemotherapy Regimens for Non-Metastatic Conventional Appendicular Osteosarcoma: A Literature Review Based on the Outcomes

Osteosarcoma is a rare condition with a complex treatment. Most protocols include neoadjuvant chemotherapy, surgery, and consolidation chemotherapy as the standard of treatment. However, the use of neoadjuvant chemotherapy lacks scientific evidence proving superiority in opposition to the use of isolated chemotherapy in an adjuvant regimen after surgery. We conducted a review for studies published in English between 1980 and 2020, using the MEDLINE/PubMed and Scopus electronic databases, to evaluate the outcomes when using neoadjuvant chemotherapy or adjuvant chemotherapy strategies in the treatment of non-metastatic appendicular osteosarcoma, as well as the toxicity associated with different chemotherapeutic regimens. Patients were divided into a neoadjuvant chemotherapy group (NAC) and adjuvant chemotherapy group (ACT), depending on the chemotherapy regimen used in association with surgery. A total of 1254 articles in English were screened by title and abstract, and 146 were pre-selected for full reading and analysis. A total of 24 assays matching the inclusion criteria were selected: 10 prospective and 14 retrospective studies. This review points to an absence of significative differences in outcomes, namely overall survival, disease-free survival/event-free survival rates, or toxicity, regarding neoadjuvant or single adjuvant chemotherapy strategies used in the treatment of appendicular non-metastatic osteosarcomas. However, there is a significative difference in population dimensions between the NAC and the ACT groups. Additionally, clinical presentation, tumor localization, tumor volume, or histological type were not considered, with these variables presenting the potential to influence these results. Despite these limitations, our findings should allow a re-thinking of our current practice and promote new opportunities to optimize treatment, always looking towards better survival and lower complications rates.

Tumour extracellular vesicles and particles induce liver metabolic dysfunction

Cancer alters the function of multiple organs beyond those targeted by metastasis1,2. Here we show that inflammation, fatty liver and dysregulated metabolism are hallmarks of systemically affected livers in mouse models and in patients with extrahepatic metastasis. We identified tumour-derived extracellular vesicles and particles (EVPs) as crucial mediators of cancer-induced hepatic reprogramming, which could be reversed by reducing tumour EVP secretion via depletion of Rab27a. All EVP subpopulations, exosomes and principally exomeres, could dysregulate hepatic function. The fatty acid cargo of tumour EVPs-particularly palmitic acid-induced secretion of tumour necrosis factor (TNF) by Kupffer cells, generating a pro-inflammatory microenvironment, suppressing fatty acid metabolism and oxidative phosphorylation, and promoting fatty liver formation. Notably, Kupffer cell ablation or TNF blockade markedly decreased tumour-induced fatty liver generation. Tumour implantation or pre-treatment with tumour EVPs diminished cytochrome P450 gene expression and attenuated drug metabolism in a TNF-dependent manner. We also observed fatty liver and decreased cytochrome P450 expression at diagnosis in tumour-free livers of patients with pancreatic cancer who later developed extrahepatic metastasis, highlighting the clinical relevance of our findings. Notably, tumour EVP education enhanced side effects of chemotherapy, including bone marrow suppression and cardiotoxicity, suggesting that metabolic reprogramming of the liver by tumour-derived EVPs may limit chemotherapy tolerance in patients with cancer. Our results reveal how tumour-derived EVPs dysregulate hepatic function and their targetable potential, alongside TNF inhibition, for preventing fatty liver formation and enhancing the efficacy of chemotherapy.

Pathologic Complete Response and Clinical Outcomes in Patients With Localized Soft Tissue Sarcoma Treated With Neoadjuvant Chemoradiotherapy or Radiotherapy: The NRG/RTOG 9514 and 0630 Nonrandomized Clinical Trials

Importance

Pathologic complete response (pCR) may be associated with prognosis in patients with soft tissue sarcoma (STS).

Objective

We sought to determine the prognostic significance of pCR on survival outcomes in STS for patients receiving neoadjuvant chemoradiotherapy (CT-RT) (Radiation Therapy Oncology Group [RTOG] 9514) or preoperative image-guided radiotherapy alone (RT, RTOG 0630) and provide a long-term update of RTOG 0630.

Design, Setting, and Participants

RTOG has completed 2 multi-institutional, nonrandomized phase 2 clinical trials for patients with localized STS. One hundred forty-three eligible patients from RTOG 0630 (n = 79) and RTOG 9514 (n = 64) were included in this ancillary analysis of pCR and 79 patients from RTOG 0630 were evaluated for long-term outcomes.

Intervention

Patients in trial 9514 received CT interdigitated with RT, whereas those in trial 0630 received preoperative RT alone.

Main Outcomes and Measures

Overall and disease-free survival (OS and DFS) rates were estimated by the Kaplan-Meier method. Hazard ratios (HRs) and P values were estimated by multivariable Cox model stratified by study, where possible; otherwise, P values were calculated by stratified log-rank test. Analysis took place between December 14, 2016, to April 13, 2017.

Results

Overall there were 42 (53.2%) men; 68 (86.1%) were white; with a mean (SD) age of 59.6 (14.5) years. For RTOG 0630, at median follow-up of 6.0 years, there was 1 new in-field recurrence and 1 new distant failure since the initial report. From both studies, 123 patients were evaluable for pCR: 14 of 51 (27.5%) in trial 9514 and 14 of 72 (19.4%) in trial 0630 had pCR. Five-year OS was 100% for patients with pCR vs 76.5% (95% CI, 62.3%-90.8%) and 56.4% (95% CI, 43.3%-69.5%) for patients with less than pCR in trials 9514 and 0630, respectively. Overall, pCR was associated with improved OS (P = .01) and DFS (HR, 4.91; 95% CI, 1.51-15.93; P = .008) relative to less than pCR. Five-year local failure rate was 0% in patients with pCR vs 11.7% (95% CI, 3.6%-25.1%) and 9.1% (95% CI, 3.3%-18.5%) for patients with less than pCR in 9514 and 0630, respectively. Histologic types other than leiomyosarcoma, liposarcoma, and myxofibrosarcoma were associated with worse OS (HR, 2.24; 95% CI, 1.12-4.45).

Conclusions and Relevance

This ancillary analysis of 2 nonrandomized clinical trials found that pCR was associated with improved survival in patients with STS and should be considered as a prognostic factor of clinical outcomes for future studies.

Trial Registration

ClinicalTrials.gov Identifiers: RTOG 0630 (NCT00589121); RTOG 9514 (NCT00002791).

The Survival Outcomes, Prognostic Factors and Adverse Events following Systemic Chemotherapy Treatment in Bone Sarcomas: A Retrospective Observational Study from the Experience of the Cancer Referral Center in Northern Thailand

This study aimed to assess survival outcomes, prognostic factors, and adverse events following chemotherapy treatment for osteosarcoma and Ewing’s sarcoma. This retrospective observational study was conducted to collect the data of the patients with osteosarcoma or Ewing’s sarcoma who received chemotherapy treatment between 2008 and 2019. The flexible parametric survival model was performed to explore the adjusted survival probability and the prognostic factors. A total of 102 patients (79 with osteosarcoma and 23 with Ewing’s sarcoma) were included. The estimated 5-year disease-free survival (DFS) and 5-year overall survival (OS) probabilities in patients with resectable disease were 60.9% and 63.3% for osteosarcoma, and 54.4% and 88.3% for Ewing’s sarcoma, respectively, whereas the 5-year DFS and 5-year OS for those with unresectable/metastatic disease remained below 25%. Two prognostic factors for osteosarcoma included a response to neoadjuvant chemotherapy and female gender. Ewing’s sarcoma patients aged 25 years and older were significantly associated with poorer survival outcomes. Of 181 chemotherapy treatment cycles, common self-reported adverse symptoms included tumor pain (n = 32, 17.7%), fever (n = 21, 11.6%), and fatigue (n = 16, 8.8%), while common grade III adverse events included febrile neutropenia (n = 13, 7.3%) and neutropenia (n = 9, 5.1%). There was no chemotherapy-related mortality (grade V) or anaphylaxis events.

T2-weighted MRI radiomics in high-grade intramedullary osteosarcoma: predictive accuracy in assessing histologic response to chemotherapy, overall survival, and disease-free survival

OBJECTIVE

To analyze radiomic features obtained from pre-treatment T2-weighted MRI acquisitions in patients with histologically proven intramedullary high-grade osteosarcomas and assess the accuracy of radiomic modelling as predictive biomarker of tumor necrosis following neoadjuvant chemotherapy (NAC), overall survival (OS), and disease-free survival (DFS).

MATERIALS AND METHODS

Pre-treatment MRI exams in 105 consecutive patients who underwent NAC and resection of high-grade intramedullary osteosarcoma were evaluated. Histologic necrosis following NAC, and clinical outcome-survival data was collected for each case. Radiomic features were extracted from segmentations performed by two readers, with poorly reproducible features excluded from further analysis. Cox proportional hazard model and Spearman correlation with multivariable modelling were used for assessing relationships of radiomics features with OS, DFS, and histologic tumor necrosis.

RESULTS

Study included 74 males, 31 females (mean 32.5yrs, range 15-77 years). Histologic assessment of tumor necrosis following NAC was available in 104 cases, with good response (≥ 90% necrosis) in 41, and poor response in 63. Fifty-three of 105 patients were alive at follow-up (median 40 months, range: 2-213 months). Median OS was 89 months. Excluding 14 patients with metastases at presentation, median DFS was 19 months. Eleven radiomics features were employed in final radiomics model predicting histologic tumor necrosis (mean AUC 0.708 ± 0.046). Thirteen radiomic features were used in model predicting OS (mean concordance index 0.741 ± 0.011), and 12 features retained in predicting DFS (mean concordance index 0.745 ± 0.010).

CONCLUSIONS

T2-weighted MRI radiomic models demonstrate promising results as potential prognostic biomarkers of prospective tumor response to neoadjuvant chemotherapy and prediction of clinical outcomes in conventional osteosarcoma.

Formulation and validation of a baseline prognostic score for osteosarcoma treated uniformly with a non-high dose methotrexate-based protocol from a low middle income healthcare setting: a single centre analysis of 594 patients

Introduction

The outcomes of osteosarcoma in low middle income countries (LMICs) are different due to patients presenting in advanced stages, resource constraints and the use of non-high-dose-methotrexate (HDMTX)-based regimens. This study derived and validated a prognostic score for osteosarcoma that integrates biologic and social factors and is tailored for patients from an LMIC setting using a non-HDMTX-based protocol.

Materials and methods

A retrospective study including osteosarcoma patients enrolled for treatment at a single tertiary care centre in India between 2003-19 was conducted. Baseline biologic and social characteristics were extracted from medical records and survival outcomes were noted. The cohort was randomised into a derivation and validation cohort. Multivariable Cox regression was used to identify baseline characteristics that were independently prognostic for survival outcomes in the derivation cohort. A score was derived from the prognostic factors identified in the derivation cohort and further validated in the validation cohort with estimation of its predictive ability.

Results

594 patients with osteosarcoma were eligible for inclusion in the study. Around one-third of the cohort had metastatic disease with 59% of the patients residing in rural areas. The presence of metastases at baseline (HR 3.39; p<0.001; score=3), elevated serum alkaline phosphatase (SAP) >450 IU/L (HR 1.57; p=0.001; score=1) and baseline tumour size > 10 cm (HR 1.68; p<0.001; score=1) were identified to be independent factors predicting inferior event free survival (EFS) and were included in development of the prognostic score. Patients were categorized as low risk (score 0), intermediate risk (score 1-3) and high risk (4-5). Harrell's c-indices for the score were 0.682, 0.608 and 0.657 respectively for EFS in the derivation, validation and whole cohort respectively. The timed AUC of ROC was 0.67 for predicting 18-month EFS in the derivation, validation and whole cohorts while that for 36-month EFS were 0.68, 0.66 and 0.68 respectively.

Conclusions

The study describes the outcomes among osteosarcoma patients from an LMIC treated uniformly with a non-HDMTX-based protocol. Tumor size, baseline metastases and SAP were prognostic factors used to derive a score with good predictive value for survival outcomes. Social factors did not emerge as determinants of survival.

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.

Identification and Development of an Age-Related Classification and Signature to Predict Prognosis and Immune Landscape in Osteosarcoma

Background. In childhood and adolescence, the prevailing bone tumor is osteosarcoma associated with frequent recurrence and lung metastasis. This research focused on predicting the survival and immune landscape of osteosarcoma by developing a prognostic signature and establishing aging-related genes (ARGs) subtypes. Methods. The training group comprised of the transcriptomic and associated clinical data of 84 patients with osteosarcoma accessed at the TARGET database and the validation group consisted of 53 patients from GSE21257. The aging-related subtypes were identified using unsupervised consensus clustering analysis. The ARG signature was developed utilizing multivariate Cox analysis and LASSO regression. The prognostic value was assessed using the univariate and multivariate Cox analyses, Kaplan-Meier plotter, time-dependent ROC curve, and nomogram. The functional enrichment analyses were performed by GSEA, GO, and KEGG analysis, while the ssGSEA, ESTIMATE, and CIBERSORT analyses were conducted to reveal the immune landscape in osteosarcoma. Results. The two clusters of osteosarcoma patients formed based on 543 ARGs, depicted a considerable difference in the tumor microenvironment, and the overall survival and immune cell infiltration rate varied as well. Among these, the selected 23 ARGs were utilized for the construction of an efficient predictive prognostic signature for the overall survival prediction. The testing in the validation group of osteosarcoma patients confirmed the status of the high-risk score as an independent indicator for poor prognosis, which was already identified as such using the univariate and multivariate Cox analyses. Furthermore, the ARG signature could distinguish different immune-related functions, infiltration status of immune cells, and tumor microenvironment, as well as predict the immunotherapy response of osteosarcoma patients. Conclusion. The aging-related subtypes were identified and a prognostic signature was developed in this research, which determined different prognoses and allowed for treatment of osteosarcoma patients to be tailored. Additionally, the immunotherapeutic response of individuals with osteosarcoma could also be predicted by the ARG signature.

Tumor lysis syndrome following ifosfamide monotherapy in metastatic osteosarcoma: a case report and review of the literature

Background

Tumor lysis syndrome is an oncologic emergency that involves multiple metabolic abnormalities and clinical symptoms such as acute renal failure, cardiac arrhythmias, seizures, and multiorgan failure, and may be fatal if not promptly recognized. Tumor lysis syndrome occurs most often in patients with hematologic malignancies, and relatively few cases have been described in patients with sarcoma.

Case presentation

A 64-year-old male of Asian heritage presented to his primary care physician with a right lower-extremity mass and was ultimately diagnosed with widely metastatic osteosarcoma. He was treated with one cycle of cisplatin and doxorubicin that was complicated by hypervolemia and hypoxic respiratory failure. Given concerns for volume overload, therapy was changed to single-agent, dose-reduced ifosfamide. After receiving one dose of ifosfamide 1 g/m² (1.8 g total) intravenously over 1 hour, the patient developed renal failure, hyperuricemia, hyperkalemia, hyperphosphatemia, and lactic acidosis. The patient ultimately died from severe electrolyte abnormalities associated with tumor lysis syndrome.

Conclusion

This is the first instance of tumor lysis syndrome described in a patient with osteosarcoma undergoing ifosfamide monotherapy. Clinicians must be vigilant in identifying tumor lysis syndrome regardless of the malignancy type or chemotherapy regimen in order to prevent potentially fatal complications.

Thymoquinone Potentiates Methotrexate Mediated-Apoptosis in Saos-2 Osteosarcoma Cell Line

INTRODUCTION

Recently, various studies have concentrated on the therapeutic potential of thymoquinone (TQ), a natural polyphenol, in various human malignancies, including osteosarcoma. However, the underlying mechanisms in TQ-mediated anti-cancer effects are not yet fully understood. Therefore, the present study investigated the effect of TQ on methotrexate (MTX)-induced apoptosis in Saos-2 cells.

METHODS

Saos-2 cells were treated with MTX, TQ, and a combination of both, and cell viability was assessed by MTT assay. mRNA expression of apoptotic markers, including Bax, Bcl-2, and caspase-3, was assessed using quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

MTX resulted in significant inhibition of cell proliferation in a dose-dependent manner. The combination of TQ and MTX inhibited proliferation compared to single treatments (P<0.05). TQ also induced apoptosis by regulating pro-apoptotic markers including Bax and caspase-3 and reducing anti-apoptotic mediators including Bcl-2. In addition, TQ increased MTX-induced apoptosis in Saos-2 cells.

CONCLUSION

The findings of the present study highlight new insights into understanding the role of TQ as a potential therapeutic agent in osteosarcoma by increasing MTX-induced apoptosis.

Modelling time-varying covariates effect on survival via functional data analysis: application to the MRC BO06 trial in osteosarcoma

Time-varying covariates are of great interest in clinical research since they represent dynamic patterns which reflect disease progression. In cancer studies biomarkers values change as functions of time and chemotherapy treatment is modified by delaying a course or reducing the dose intensity, according to patient’s toxicity levels. In this work, a Functional covariate Cox Model (FunCM) to study the association between time-varying processes and a time-to-event outcome is proposed. FunCM first exploits functional data analysis techniques to represent time-varying processes in terms of functional data. Then, information related to the evolution of the functions over time is incorporated into functional regression models for survival data through functional principal component analysis. FunCM is compared to a standard time-varying covariate Cox model, commonly used despite its limiting assumptions that covariate values are constant in time and measured without errors. Data from MRC BO06/EORTC 80931 randomised controlled trial for treatment of osteosarcoma are analysed. Time-varying covariates related to alkaline phosphatase levels, white blood cell counts and chemotherapy dose during treatment are investigated. The proposed method allows to detect differences between patients with different biomarkers and treatment evolutions, and to include this information in the survival model. These aspects are seldom addressed in the literature and could provide new insights into the clinical research.

Development and validation of apoptosis-related signature and molecular subtype to improve prognosis prediction in osteosarcoma patients

BACKGROUND

Previous evidence has shown that apoptosis performs integral functions in the tumorigenesis and development of various tumors. Therefore, this study aimed to establish a molecular subtype and prognostic signature based on apoptosis-related genes (ARGs) to understand the molecular mechanisms and predict prognosis in patients with osteosarcoma.

METHODS

The GEO and TARGET databases were utilized to obtain the expression levels of ARGs and clinical information of osteosarcoma patients. Consensus clustering analysis was used to explore the different molecular subtypes based on ARGs. GO, KEGG, GSEA, ESTIMATE, and ssGSEA analyses were performed to examine the differences in biological functions and immune characteristics between the distinct molecular subtypes. Then, we constructed an ARG signature by LASSO analysis. The prognostic significance of the ARG signature in osteosarcoma was determined by Kaplan-Meier plotter, Cox regression, and nomogram analyses.

RESULTS

Two apoptosis-related subtypes were identified. Cluster 1 had a better prognosis, higher immunogenicity, and immune cell infiltration, as well as a better response to immunotherapy than Cluster 2. We discovered that patients in the high-risk cohort had a lower survival rate than those in the low-risk cohort according to the ARG signature. Furthermore, Cox regression analysis confirmed that a high risk score independently acted as an unfavorable prognostic marker. Additionally, the nomogram combining risk scores with clinical characteristics can improve prediction efficiency.

CONCLUSION

We demonstrated that patients suffering from osteosarcoma may be classified into two apoptosis-related subtypes. Moreover, we developed an ARG prognostic signature to predict the prognosis status of osteosarcoma patients.

Short-term and long-term prognostic value of histological response and intensified chemotherapy in osteosarcoma: a retrospective reanalysis of the BO06 trial

OBJECTIVES

Cure rate models accounting for cured and uncured patients, provide additional insights into long and short-term survival. We aim to evaluate the prognostic value of histological response and chemotherapy intensification on the cure fraction and progression-free survival (PFS) for the uncured patients.

DESIGN

Retrospective analysis of a randomised controlled trial, MRC BO06 (EORTC 80931).

SETTING

Population-based study but proposed methodology can be applied to other trial designs.

PARTICIPANTS

A total of 497 patients with resectable highgrade osteosarcoma, of which 118 were excluded because chemotherapy was not started, histological response was not reported, abnormal dose was reported or had disease progression during treatment.

INTERVENTIONS

Two regimens with the same anticipated cumulative dose (doxorubicin 6×75 mg/m²/week; cisplatin 6×100 mg/m²/week) over different time schedules: every 3 weeks in regimen-C and every 2 weeks in regimen-DI.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome is PFS computed from end of treatment because cure, if it occurs, may happen at any time during treatment. A mixture cure model is used to study the effect of histological response and intensified chemotherapy on the cure status and PFS for the uncured patients.

RESULTS

Histological response is a strong prognostic factor for the cure status (OR 3.00, 95% CI 1.75 to 5.17), but it has no clear effect on PFS for the uncured patients (HR 0.78, -95% CI 0.53 to 1.16). The cure fractions are 55% (46%-63%) and 29% (22%-35%), respectively, among patients with good and poor histological response (GR, PR). The intensified regimen was associated with a higher cure fraction among PR (OR 1.90, 95% CI 0.93 to 3.89), with no evidence of effect for GR (OR 0.78, 95% CI 0.38 to 1.59).

CONCLUSIONS

Accounting for cured patients is valuable in distinguishing the covariate effects on cure and PFS. Estimating cure chances based on these prognostic factors is relevant for counselling patients and can have an impact on treatment decisions.

TRIAL REGISTRATION NUMBER

ISRCTN86294690.

SELNET clinical practice guidelines for bone sarcoma

Bone sarcoma are infrequent diseases, representing < 0.2% of all adult neoplasms. A multidisciplinary management within reference centers for sarcoma, with discussion of the diagnostic and therapeutic strategies within an expert multidisciplinary tumour board, is essential for these patients, given its heterogeneity and low frequency. This approach leads to an improvement in patient's outcome, as demonstrated in several studies. The Sarcoma European Latin-American Network (SELNET), aims to improve clinical outcome in sarcoma care, with a special focus in Latin-American countries. These Clinical Practice Guidelines (CPG) have been developed and agreed by a multidisciplinary expert group (including medical and radiation oncologist, surgical oncologist, orthopaedic surgeons, radiologist, pathologist, molecular biologist and representatives of patients advocacy groups) of the SELNET consortium, and are conceived to provide the standard approach to diagnosis, treatment and follow-up of bone sarcoma patients in the Latin-American context.

Impact of treatment refusal and abandonment on survival outcomes in pediatric osteosarcoma in Southeast Asia: A multicenter study

BACKGROUND

Treatment refusal and abandonment (TxRA) are major barriers to improving outcomes among children with sarcomas of the extremities as curative treatment options bearing on amputation or disfiguring surgery, particularly in countries with limited resources. A multi-institutional retrospective study was conducted to determine the predictive factors for TxRA among patients with osteosarcoma associated with survival outcomes across Southeast Asia (SEA).

METHODS

Pediatric patients with osteosarcoma treated between January 1998 and December 2017 in four SEA pediatric oncology centers from three countries were studied. Nelson-Aalen estimates, Kaplan-Meier method, and Cox's proportion hazard model were applied to address the cumulative incidence, survival outcomes, and to identify prognostic factors associated with TxRA.

RESULTS

From a total of 208 patients with osteosarcoma enrolled; 18 (8.7%) patients refused and 41 (19.7%) patients abandoned treatment. Income classification of countries, age at diagnosis, tumor size, disease extent, chemotherapy protocols, and types of surgery were associated with TxRA. Tumor size more than 15 cm was an independent risk factor associated with TxRA. The 5-year overall and relapse-free survivals were 49.4% and 50.4%, respectively. However, these rates declined further to 37.9% and 35.8%, respectively, when TxRA were considered as events. Tumor size larger than 15 cm and metastatic disease were independent risk factors associated with TxRA-sensitive outcomes.

CONCLUSION

The prevalence of TxRA was high in SEA, particularly in lower middle-income countries. Factors associated with TxRA related to tumor burden. Treatment outcomes could be substantially improved by lowering the refusal and abandonment rates.

Genome-wide DNA methylation patterns reveal clinically relevant predictive and prognostic subtypes in human osteosarcoma

Aberrant methylation of genomic DNA has been reported in many cancers. Specific DNA methylation patterns have been shown to provide clinically useful prognostic information and define molecular disease subtypes with different response to therapy and long-term outcome. Osteosarcoma is an aggressive malignancy for which approximately half of tumors recur following standard combined surgical resection and chemotherapy. No accepted prognostic factor save tumor necrosis in response to adjuvant therapy currently exists, and traditional genomic studies have thus far failed to identify meaningful clinical associations. We studied the genome-wide methylation state of primary tumors and tested how they predict patient outcomes. We discovered relative genomic hypomethylation to be strongly predictive of response to standard chemotherapy. Recurrence and survival were also associated with genomic methylation, but through more site-specific patterns. Furthermore, the methylation patterns were reproducible in three small independent clinical datasets. Downstream transcriptional, in vitro, and pharmacogenomic analysis provides insight into the clinical translation of the methylation patterns. Our findings suggest the assessment of genomic methylation may represent a strategy for stratifying patients for the application of alternative therapies.

Resource-appropriate selection of osteosarcoma treatment protocols in low- and middle-income countries

Osteosarcoma is a rare malignancy; however, it is still the most common primary bone tumor in adolescents and young adults. Chemotherapy improves survival indubitably in osteosarcoma; nevertheless, the concern is the stagnant progress since the last several decades. There are a handful of active agents and unresolved issues, especially in choosing the ideal chemotherapy regimen. The oncology community is in equipoise regarding the position of high-dose methotrexate (HDMTX), mandatory or adjunct. The choice of therapy becomes widely relevant, including in low- and middle-income countries (LMIC), where HDMTX administration brings additional complexities. Research into novel non-HDMTX-based protocols adapted to the available resources is pivotal in improving disease outcomes, especially in LMIC. The current review focuses on real-world challenges in decision-making and provides a comprehensive overview of the evolution of treatment protocols in LMIC.

Current approaches to management of bone sarcoma in adolescent and young adult patients

Bone tumors are a group of histologically diverse diseases that occur across all ages. Two of the commonest, osteosarcoma (OS) and Ewing sarcoma (ES), are regarded as characteristic adolescent and young adult (AYA) cancers with an incidence peak in AYAs. They are curable for some but associated with unacceptably high rates of treatment failure and morbidity. The introduction of effective new therapeutics for bone sarcomas is slow, and to date, complex biology has been insufficiently characterized to allow more rapid therapeutic exploitation. This review focuses on current standards of care, recent advances that have or may soon change that standard of care and challenges to the expert clinical research community that we suggest must be met.

Development and Validation of Nomograms to Assess Risk Factors and Overall Survival Prediction for Lung Metastasis in Young Patients with Osteosarcoma: A SEER-Based Study

BACKGROUND

To establish two nomograms to quantify the diagnostic factors of lung metastasis (LM) and their role in assessing prognosis in young patients with LM osteosarcoma.

METHODS

A total of 618 osteosarcoma young patients from 2010 to 2015 were included from the Surveillance, Epidemiology, and End Results (SEER) database. Another 131 patients with osteosarcoma from local hospitals were also collected as an external validation set. Patients were randomized into training sets (n = 434) and validation sets (n = 184) with a ratio of 7:3. Univariate and multivariate logistic regression analyses were used to identify the risk factor for LM and were used to construct the nomogram. Risk variables for the overall survival rate of patients with LM were evaluated by Cox regression. Another nomogram was also constructed to predict survival rates. The results were validated using bootstrap resampling and retrospective research on 131 osteosarcoma young patients from 2010 to 2019 at three local hospitals.

RESULTS

There were 114 (18.45%) patients diagnosed as LM at initial diagnosis. The multivariate logistic regression analysis suggested that T stage, N stage, and bone metastasis were independent risk factors for LM in newly diagnosed young osteosarcoma patients (P < 0.001). The ROC analysis revealed that area under the curve (AUC) values were 0.751, 0.821, and 0.735 in the training set, internal validation set, and external validation set, respectively, indicating good predictive discrimination. The multivariate Cox proportional hazard regression analysis suggested that age, surgery, chemotherapy, primary site, and bone metastasis were prognostic factors for young osteosarcoma patients with LM. The time-dependent ROC curves showed that the AUCs for predicting 1-year, 2-year, and 3-year survival rates were 0.817, 0.792, and 0.815 in the training set and 0.772, 0.807, and 0.804 in the internal validation set, respectively. As for the external validation set, the AUCs for predicting 1-year, 2-year, and 3-year survival rates were 0.787, 0.818, and 0.717.

CONCLUSIONS

The nomograms can help clinicians strengthen their personal decision-making and can improve the prognosis of osteosarcoma patients.

Advances in the Research of Osteosarcoma Stem Cells and its Related Genes

Osteosarcoma is a malignant tumor that often occurs in adolescents. There is an urgent need of new treatment options for osteosarcoma due to its poor prognosis after metastasis. Cancer stem cell theory states that cancer stem cells represent a small proportion of cancer cells. These cancer stem cells have self-renewal ability and are closely associated with cancer growth and metastasis as well as chemotherapy resistance. Similarly, osteosarcoma stem cells (OSCs) play an important role in the growth, metastasis, and chemotherapy resistance of osteosarcoma cells. Targeting OSCs may represent a future treatment of osteosarcoma. Furthermore, some genes have shown to regulate the growth, metastasis, and chemotherapy resistance of osteosarcoma cells by altering the stemness of OSCs. Targeting these genes may help in the treatment of osteosarcoma. This review mainly discusses recent advances in the research of OSCs and its related genes. This article is protected by copyright. All rights reserved.

Novel longitudinal Multiple Overall Toxicity (MOTox) score to quantify adverse events experienced by patients during chemotherapy treatment: a retrospective analysis of the MRC BO06 trial in osteosarcoma

OBJECTIVES

This study aims at exploring and quantifying multiple types of adverse events (AEs) experienced by patients during cancer treatment. A novel longitudinal score to evaluate the Multiple Overall Toxicity (MOTox) burden is proposed. The MOTox approach investigates the personalised evolution of high overall toxicity (high-MOTox) during the treatment.

DESIGN

Retrospective analysis of the MRC-BO06/EORTC-80931 randomised controlled trial for osteosarcoma.

SETTING

International multicentre population-based study.

PARTICIPANTS

A total of 377 patients with resectable high-grade osteosarcoma, who completed treatment within 180 days after randomisation without abnormal dosages (+25% higher than planned).

INTERVENTIONS

Patients were randomised to six cycles of conventional versus dose-intense regimens of doxorubicin and cisplatin. Non-haematological toxicity data were collected prospectively and graded according to the Common Terminology Criteria for Adverse Events (CTCAE).

MAIN OUTCOME MEASURES

The MOTox score described the overall toxicity burden in terms of multiple toxic AEs, maximum-severity episode and cycle time-dimension. Evolution of high-MOTox was assessed through multivariable models, that investigated the impact of personalised characteristics (eg, achieved chemotherapy dose, previous AEs or biochemical factors) cycle-by-cycle.

RESULTS

A cycle-by-cycle analysis identifies different evolutions of MOTox levels during treatment, detecting differences in patients' health. Mean MOTox values and percentages of patients with high-MOTox decreased cycle-by-cycle from 2.626 to 1.953 and from 57.8% to 36.6%, respectively. High-MOTox conditions during previous cycles were prognostic risk factors for a new occurrence (ORs range from 1.522 to 4.439), showing that patient's history of toxicities played an important role in the evolution of overall toxicity burden during therapy. Conventional regimen may be preferred to dose-intense in terms of AEs at cycles 2-3 (p<0.05).

CONCLUSIONS

The novel longitudinal method developed can be applied to any cancer studies with CTCAE-graded toxicity data. After validation in other studies, the MOTox approach may lead to improvements in healthcare assessment and treatment planning.

TRIAL REGISTRATION NUMBER

ISRCTN86294690; Post-results.

Prognostic Significance of Clinical and Post-Neoadjuvant Chemotherapy Associated Histomorphological Parameters in Osteosarcoma: A Retrospective Study from a Tertiary Care Center

Introduction Osteosarcoma is the most prevalent bone cancer in adolescents. Neoadjuvant chemotherapy (NACT) followed by resection is the current modality of treatment for osteosarcoma. Histological evaluation of extent of tumor necrosis on resection is a well-established prognostic indicator in osteosarcoma correlating with survival in most cases.

Objectives The main objective of this study was to establish prognostic significance of various clinical and histological parameters post-NACT in osteosarcoma and to compare the integrated prognostic index proposed by Chui et al, with grading of response to NACT by Huvos and Rosen for osteosarcoma.

Materials and Methods This is a retrospective study done over a period of four years and includes 47 cases of osteosarcoma treated with NACT. All slides were reviewed and association of various clinical and histological parameters with overall survival was assessed with chi-squared test and Cox-regression analysis.

Results Statistical analysis revealed the prognostic significance of age at presentation, anatomic site, primary tumor size, metastatic status, and clinical stage. Histological parameters such as mitosis ≥10/10hpfs, ≥10% residual tumor were significantly associated with poor survival. Tumor necrosis ≥ 90% (excluding areas of hemorrhage, fibrosis and acellular osteoid) was significantly associated with increased survival. An integrated prognostic index formed by combining above parameters gives a better estimate of overall survival compared with residual disease or necrosis alone.

Conclusion Integrated prognostic index improves prognostication in patients treated for osteosarcoma.

A Simulation Study to Compare the Predictive Performance of Survival Neural Networks with Cox Models for Clinical Trial Data

Background

Studies focusing on prediction models are widespread in medicine. There is a trend in applying machine learning (ML) by medical researchers and clinicians. Over the years, multiple ML algorithms have been adapted to censored data. However, the choice of methodology should be motivated by the real-life data and their complexity. Here, the predictive performance of ML techniques is compared with statistical models in a simple clinical setting (small/moderate sample size and small number of predictors) with Monte-Carlo simulations.

Methods

Synthetic data (250 or 1000 patients) were generated that closely resembled 5 prognostic factors preselected based on a European Osteosarcoma Intergroup study (MRC BO06/EORTC 80931). Comparison was performed between 2 partial logistic artificial neural networks (PLANNs) and Cox models for 20, 40, 61, and 80% censoring. Survival times were generated from a log-normal distribution. Models were contrasted in terms of the C-index, Brier score at 0-5 years, integrated Brier score (IBS) at 5 years, and miscalibration at 2 and 5 years (usually neglected). The endpoint of interest was overall survival.

Results

PLANNs original/extended were tuned based on the IBS at 5 years and the C-index, achieving a slightly better performance with the IBS. Comparison with Cox models showed that PLANNs can reach similar predictive performance on simulated data for most scenarios with respect to the C-index, Brier score, or IBS. However, Cox models were frequently less miscalibrated. Performance was robust in scenario data where censored patients were removed before 2 years or curtailing at 5 years was performed (on training data).

Conclusion

Survival neural networks reached a comparable predictive performance with Cox models but were generally less well calibrated. All in all, researchers should be aware of burdensome aspects of ML techniques such as data preprocessing, tuning of hyperparameters, and computational intensity that render them disadvantageous against conventional regression models in a simple clinical setting.

Assessment of Risk of Bias in Osteosarcoma and Ewing's Sarcoma Randomized Controlled Trials: A Systematic Review

Aim: The aim of this study was to systematically assess the risk of bias in osteosarcoma and Ewing’s sarcoma (ES) randomized controlled trials (RCT) and to examine the relationships between bias and conflict of interest/industry sponsorship. Methods: An OVID-MEDLINE search was performed (1976–2019). Using the Cochrane Collaboration guidelines, two reviewers independently assessed the prevalence of risk of bias in different RCT design domains. The relationship between conflicts of interest and industry funding with the frequency of bias was examined. Results: 73 RCTs met inclusion criteria. Prevalence of low-risk bias domains was 47.3%, unclear-risk domains 47.8%, and 4.9% of the domains had a high-risk of bias. Domains with the highest risk of bias were blinding of participants/personnel and outcome assessors, followed by randomization and allocation concealment. Overtime, frequency of unclear-risk of bias domains decreased (χ² = 5.32, p = 0.02), whilst low and high-risk domains increased (χ² = 8.13, p = 0.004). Studies with conflicts of interest and industry sponsorships were 4.2 and 3.1 times more likely to have design domains with a high-risk of bias (p < 0.05). Conclusion: This study demonstrates that sources of potential bias are prevalent in both osteosarcoma and ES RCTs. Studies with financial conflicts of interest and industry sponsors were significantly more likely to have domains with a high-risk of bias. Improvements in reporting and adherence to proper methodology will reduce the risk of bias and improve the validity of the results of RCTs in osteosarcoma and ES.

Grossing and reporting of bone tumor specimens in surgical oncology: Rationale with current evidence and recent updates

Primary bone tumors, including sarcomas, are rare tumors and require a multidisciplinary approach, including inputs from a radiologist, pathologist, medical oncologist, and surgical and radiation oncologist, for optimal management. Over the years, there has been a paradigm shift toward the treatment of bone sarcomas, from radical resections to conservative surgical procedures, to achieve improved clinical and functional outcomes. This has led to receiving and processing various types of specimens in orthopedic oncopathology. Grossing and reporting of bone tumors require expertise. This review focuses upon the types of biopsies, grossing techniques of various specimens in orthopedic oncology and reporting, with rationale and recommendations from pathologists, actively involved in reporting and pursuing a special interest in bone tumors, based on current evidence. Furthermore, there is a section on some of the updates in the diagnosis of bone tumors, based on the recent fifth edition of the World Health Organization classification of tumors of soft tissues and bone.

Mesenchymal stem cells plus bone repair materials as a therapeutic strategy for abnormal bone metabolism: Evidence of clinical efficacy and mechanisms of action implied

The regeneration process of human bones is very complicated, the management and treatment of bone damage caused by diseases are the main problems faced by clinicians worldwide. It is known that cell-based stem cell therapy together with biomaterials is a fast-developing method of tissue regeneration. This review focuses on the different types and main characteristics of scaffolds and stem cells suitable for bone regeneration, and aims to provide a state-of-the-art description of the current treatment of common bone metabolism related diseases such as osteoarthritis, osteoporosis and osteosarcoma and the strategies based on stem cell biological scaffolds used in bone tissue engineering. This method may provide a new treatment option for the treatment of common bone metabolism-related diseases that cannot be cured by ordinary and routine applications. Three databases (PubMed, CNKI and Web of Science) search terms used to write this review are: "arthritis", "osteoporosis", "osteosarcoma", "bone tissue engineering", "mesenchymal stem cells", "materials", "bioactive scaffolds" and their combinations, and the most relevant studies are selected. As a conclusion, it needs to be emphasized that despite the encouraging results, further development is needed due to the need for more in-depth research, standardization of stem cell manufacturing processes, large-scale development of clinical methods for bone tissue engineering, and market regulatory approval. Although the research and application of tissue regeneration technology and stem cells are still in their infancy, the application prospect is broad and it is expected to solve the current clinical problems.

Outcomes of Osteosarcoma in Children Without High-Dose Methotrexate: Could It Be Less Toxic Without Effecting Survival Rates?

Background: Osteosarcoma (OS) is the most common primary bone sarcoma in childhood. High-dose methotrexate, doxorubicine, cisplatin, and/or ifosfamide combinations are used as standard treatment in chemotherapy and could cause serious toxicity. Another alternative chemotherapy protocol is consisting of epirubicin, ifosfamide, and cisplatin (ECI), which we use in our center. The aim of this study was to evaluate the patients with OS who were treated with ECI protocol, retrospectively. Methods: Forty-three patients with OS diagnosed at our center between December 1995 and September 2017 were evaluated retrospectively. Results: The mean follow-up period was 31 months (5-145 months). Recurrence was detected in 15 of 43 patients. When the factors affecting relapse are examined, recurrence was higher in patients who were older than 10 years at the time of diagnosis, upper extremity involvement, osteoblastic, and chondroblastic subgroups, but there was no statistically significant difference. Five-year and 10-year overall survival rates were 67.4% and 58.9%, and event-free survival rates were 54% and 47.3%, respectively. While 5-year overall survival rate was 86.7% in nonrecurrent cases, this rate was 40.9% in recurrent cases and this difference was statistically significant (p = 0.023). Just two patients died because of the toxicity. Conclusion: The prognosis of OS is still poor in relapse cases, so the choice of chemotherapy for neoadjuvant and adjuvant therapy is vital. When the risk of toxicity is also considered, the first step of ECI protocol is seen as a preferable treatment option because the survival rates are similar to the literature.

Adjuvant and neoadjuvant chemotherapy for osteosarcoma: JCOG Bone and Soft Tissue Tumor Study Group

The usefulness of adjuvant chemotherapy for high-grade osteosarcoma was established by two randomized, controlled trials conducted in the 1980s, which used six drugs, doxorubicin, cisplatin, high-dose methotrexate, bleomycin, cyclophosphamide and actinomycin D. Since then, development has been promoted in the direction of introducing preoperative chemotherapy, changing post-operative adjuvant chemotherapy according to histological effects, adding ifosfamide as a key drug and strengthening adjuvant chemotherapy. No clinical trials, however, have shown the effectiveness of study treatment, and the improvement of treatment results during that time has been slight, although the JCOG0905 study is now going to verify the effectiveness of introducing ifosfamide for patients who experienced limited preoperative therapeutic effects. We are desperately looking for a breakthrough.

PODN is a prognostic biomarker and correlated with immune infiltrates in osteosarcoma

Background

Osteosarcoma was the most common primary bone malignancy in children and adolescents. It was imperative to identify effective prognostic biomarkers for this cancer. This study was aimed to identify potential crucial genes of osteosarcoma by integrated bioinformatics analysis.

Methods

Identification of differentially expressed genes from public data gene expression profiles (GSE42352), functional and pathway enrichment analysis, protein–protein interaction (PPI) network construction and module analysis, Cox regression and survival analysis was conducted.

Results

Totally 17 co-differential genes were found to be differentially expressed. These genes were enriched in biological processes, Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Set Enrichment Analysis (GSEA) pathway of inflammatory immune response. PPI network was constructed with 63 differentially expressed genes that co-existed between the test set and the validation set. The area under the receiver operating characteristic curve (AUC value) was 0.855, which indicated that the expression of PODN had a good diagnostic value for osteosarcoma. Furthermore, Cox regression and survival analysis revealed 5 genes were statistically significant.

Conclusions

PODN was regarded as a potential biomarker for the diagnosis and prognosis of osteosarcoma, ACTA2, COL6A1, FAP, OLFML2B and COL6A3, can be used as potential prognostic indicators for osteosarcoma.

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.

Correlation between Prognostic Factors and the Histopathological Response to Neoadjuvant Chemotherapy in Osteosarcoma: A Retrospective Study

Background

Multimodality treatment, incorporating neoadjuvant chemotherapy and adjuvant chemotherapy, is the standard management plan for osteosarcoma that increases the overall survival (OS) rate. However, data regarding prognostic factors affecting the histopathological response following neoadjuvant chemotherapy is limited. Patients and Methods. We retrospectively reviewed patients diagnosed with osteosarcoma in our center between 2008 and 2018. We classified patient characteristics according to gender, age, tumor size, site and stage at diagnosis, site of metastasis, type of surgery, necrosis rate based on the Huvos grading system, and the number of neoadjuvant chemotherapy cycles. We divided response to neoadjuvant chemotherapy into poor responder for patients with Huvos grades 1 and 2 and good responder for patients with Huvos grades 3 and 4. We also documented patients' survival and follow-up information.

Results

We reviewed 64 patients within 5–65 years of age, dominated by men (62.5%). The distal femur (53.1%) was the most common site of osteosarcoma. Fifteen (23.4%) patients had a good response while 49 (76.6%) patients were poor responders to neoadjuvant chemotherapy based on the Huvos grading system. Based on multivariate analysis, gender (p = 0.012), age (p = 0.029), symptom duration (p = 0.004), and tumor enlargement after neoadjuvant chemotherapy (p < 0.001) were significantly associated with histopathological response. A scoring system was proposed integrating these significant variables (age > 20 years = 1 point, female gender = 1 point, symptom duration > 12 weeks = 1 point, and increased tumor size after neoadjuvant chemotherapy = 2 points). This scoring system divides patients into two groups with a total score of more than two predicting a poor responder to neoadjuvant chemotherapy.

Conclusions

Age, gender, symptoms duration, and tumor size after neoadjuvant chemotherapy are the prognostic features that affect the histopathological response to neoadjuvant chemotherapy in patients with osteosarcoma.

Impact of Secondary Aneurysmal Bone Cysts on Survival of Patients with Enneking Stage IIB Extremity Osteosarcoma: A Propensity Score Matching Analysis

BACKGROUND

The clinicopathology of aneurysmal bone cysts (ABCs) secondary to osteosarcoma has not yet been reported. We conduct a retrospective review of ABCs secondary to osteosarcoma to characterize clinicopathology and influence on the survival of patients with Enneking stage IIB extremity osteosarcoma.

PATIENTS AND METHODS

A total of 300 patients with Enneking stage IIB extremity osteosarcoma were eligible for analysis. These cases were divided, according to the pathology of biopsy and magnetic resonance imaging (MRI), into ABCs group and no ABCs group. Patients (ABCs versus no ABCs) were compared using a 1:2 propensity score analysis to best match between groups. Clinicopathology and survival data were analyzed.

RESULTS

The total occurrence rate of secondary ABCs was 10.3%. A higher prevalence of pathological fractures was observed in the ABCs group (22.6%) compared with the no ABCs group (8.6%) (p = 0.032). Patients with ABCs were more likely to undergo amputation compared with patients without ABCs (p = 0.007). Those with secondary ABCs had poorer response to chemotherapy before and after propensity score matching (p = 0.006 and p = 0.048, respectively). Kaplan-Meier survival analysis showed that EFS and OS distributions were not significantly different between the two patient groups. ABCs were not significantly different in terms of EFS or OS in the multivariate analysis model (p > 0.05).

CONCLUSIONS

The presence of secondary ABCs was associated with increased occurrence rate of pathological fracture and high percentage of amputation. Moreover, patients with secondary ABCs had poorer response to chemotherapy. However, the presence of secondary ABCs did not influence survival of patients with Enneking stage IIB extremity osteosarcoma.

Leptomeningeal disease from melanoma-Poor prognosis despite new therapeutic modalities

OBJECTIVE

The development of leptomeningeal disease (LMD) among melanoma patients is associated with short survival. Unspecific clinical symptoms and imprecise diagnostic criteria often delay diagnosis. Because melanoma patients with LMD have been excluded from most clinical trials, the efficacy of immune checkpoint blockade (ICB) and targeted therapies (TTs) has not been adequately investigated among these patients.

METHODS

We performed a retrospective study in two tertiary-referral skin cancer centres to evaluate the clinical characteristics, diagnostics, treatments, and overall survival (OS) of melanoma patients with LMD between June 2011 and March 2019.

RESULTS

In total, 52 patients were included. The median age at LMD diagnosis was 58 years. Most patients (n = 30, 58%) were men. The median time from the first diagnosis of unresectable disease to the first diagnosis of LMD was 8.5 months (range 0-91.5 months). Most patients (65%, n = 34) were BRAF V600 mutated. Sixteen patients (31%) presented with LMD only, whereas 36 patients (69%) presented with concomitant brain metastases at LMD diagnosis. Eleven patients (21%) showed no evidence of extracranial disease. Forty-four patients (85%) had clinical symptoms at LMD diagnosis. Forty-two patients (81%) had received at least one prior therapy. Forty patients (77%) received at least one treatment after LMD diagnosis, including TT (n = 17), ICB (n = 13), bevacizumab (n = 1), radiotherapy (n = 3), and intrathecal chemotherapy (n = 1); five patients received both TT and ICB. Twelve patients (23%) received no treatment because of rapid progression of LMD. The median OS for the entire cohort was 2.9 months (95% confidence interval [CI] 1.7-4.1). Among patients receiving systemic therapy, OS was 3.7 months (95% CI 2.4-4.9).

CONCLUSIONS

Systemic treatment with TT or ICB seems to improve OS among patients with LMD. However, despite new therapy modalities, the prognosis of LMD remains poor.

Combination immunotherapy using G-CSF and oncolytic virotherapy reduces tumor growth in osteosarcoma

BACKGROUND

Osteosarcoma is the most common malignant solid tumor that affects bones, however, survival rates of patients with relapsed osteosarcoma have not improved in the last 30 years. Oncolytic virotherapy, which uses viruses designed to selectively replicate in cancer cells, has emerged as a promising treatment for solid tumors. Our group uses mesenchymal stem cells (MSCs) to transport oncolytic adenoviruses (OAds) to the tumor site, a therapeutic strategy called Celyvir. This treatment has been already applied in human patients, canine patients and different mouse models. In parallel, previous results have probed that administration of granulocyte-colony stimulating factor (G-CSF) increased immune infiltration in tumors. We then hypothesized that the mobilization of immune cells by G-CSF may increase the antitumor efficacy of Celyvir treatment by increasing the immune infiltration into the tumors.

METHODS

In this study, we use a murine version of Celyvir consisting in murine MSCs carrying the murine OAd dlE102-here called OAd-MSCs-in an immunocompetent model of osteosarcoma. We tested the antitumoral efficacy of the combination of OAd-MSCs plus G-CSF.

RESULTS

Our results show that treatment with OAd-MSCs or the union of OAd-MSCs with G-CSF (Combination) significantly reduced tumor growth of osteosarcoma in vivo. Moreover, treated tumors presented higher tumor infiltration of immune cells-especially tumor-infiltrating lymphocytes-and reduced T cell exhaustion, which seems to be enhanced in tumors treated with the Combination. The comparison of our results to those obtained from a cohort of pediatric osteosarcoma patients showed that the virotherapy induces immunological changes similar to those observed in patients with good prognosis.

CONCLUSIONS

The results open the possibility of using cellular virotherapy for the treatment of bone cancers. Indeed, its combination with G-CSF may be considered for the improvement of the therapy.

Managing axial bone sarcomas in childhood

Introduction: Axial osteosarcoma and Ewing sarcoma are rare, aggressive neoplasms with a worse prognosis than with tumors involving the extremities because they are more likely to be associated with larger tumor volumes, older age, primary metastases, and a poor histological response to chemotherapy. The 5-year OS rates are reportedly in the range of 18-41% for axial osteosarcoma, and 46-64% for Ewing sarcoma.Area covered: The treatment of axial bone tumors is the same as for extremity bone tumors, and includes chemotherapy, surgery and/or radiotherapy.Expert opinion: Local treatment of axial tumors is particularly difficult due to their proximity to neurological and vascular structures, which often makes extensive and en bloc resections impossible without causing significant morbidity. The incidence of local relapse is consequently high, and this is the main issue in the treatment of these tumors. Radiotherapy is an option in the case of surgical resections with close or positive margins, as well as for inoperable tumors. Delivering high doses of RT to the spinal cord can be dangerous. Given the complexity and rarity of these tumors, it is essential for this subset of patients to be treated at selected reference institutions with specific expertise and multidisciplinary skills.

The prognostic significance of lymphovascular tumor invasion in localized high-grade osteosarcoma: Outcomes of a single institution over 10 years

BACKGROUNDS AND OBJECTIVES

Lymphovascular invasion (LVI) has shown evidence of an association with worse survival in high-grade osteosarcoma patients. The purpose of this investigation was to prognosticate LVI as a predictor of survival.

METHODS

This was a retrospective review of high-grade, localized osteosarcoma patients over a consecutive 10-year period. Proportional hazards regression was used to identify prognostic factors. Cumulative mortality incidence was estimated with recurrence as a competing risk.

RESULTS

Forty-two cases with a median follow-up of 64 months (range, 6-158 months) were reviewed. LVI was present in 21.4% (n = 9) cases. The five- and ten-year survivals in LVI (+) were 40% and 20%, compared to 93% and 81% in LVI (-), respectively (p < .001). After controlling for confounders, advanced age (hazards ratio [HR], 1.134; 95% confidence interval [CI], 1-1.2; p = .01) and LVI (HR, 21.768; 95% CI, 3-135; p = .001) were negative prognosticators. The cumulative incidence of recurrence was no different between LVI (+) and LVI (-) (p = .811), though the incidence of mortality was significantly higher in LVI (+) (p = .003).

CONCLUSION

The presence of LVI in the setting of high-grade, localized osteosarcoma is associated with greater rates of mortality and appears to portend a dismal prognosis.

Mechanisms of Resistance to Conventional Therapies for Osteosarcoma

Osteosarcoma (OS) is the most common primary bone tumor, mainly occurring in children and adolescents. Current standard therapy includes tumor resection associated with multidrug chemotherapy. However, patient survival has not evolved for the past decades. Since the 1970s, the 5-year survival rate is around 75% for patients with localized OS but dramatically drops to 20% for bad responders to chemotherapy or patients with metastases. Resistance is one of the biological processes at the origin of therapeutic failure. Therefore, it is necessary to better understand and decipher molecular mechanisms of resistance to conventional chemotherapy in order to develop new strategies and to adapt treatments for patients, thus improving the survival rate. This review will describe most of the molecular mechanisms involved in OS chemoresistance, such as a decrease in intracellular accumulation of drugs, inactivation of drugs, improved DNA repair, modulations of signaling pathways, resistance linked to autophagy, disruption in genes expression linked to the cell cycle, or even implication of the micro-environment. We will also give an overview of potential therapeutic strategies to circumvent resistance development.

The safety of current pharmacotherapeutic strategies for osteosarcoma

Introduction: Peri-operative chemotherapy is the backbone of treatment for patients with osteosarcoma. Methotrexate, cisplatinum, doxorubicin and ifosfamide are the main drugs used in chemotherapy regimens used for osteosarcoma.Areas covered: We have reviewed here the relevant literature related to the incidence and management of acute and late toxicities of systemic treatment used for the management of patients with osteosarcoma.Expert opinion: Early diagnosis and appropriate management of acute and late toxicities of chemotherapy is crucial for an efficient care of osteosarcoma patients. Although the incidence and management of chemotherapy-related acute toxicities are well known by most oncologists, the use of high doses of methotrexate have the potential to cause fatal toxicities and, therefore, needs careful monitoring. Moreover, the diagnosis of late toxicities is more challenging and requires long-term follow-up for an appropriate management.

TRIM21-regulated Annexin A2 plasma membrane trafficking facilitates osteosarcoma cell differentiation through the TFEB-mediated autophagy

Osteosarcoma (OS) is the most common primary malignant bone tumor in children and adolescents, which is characterized by dysfunctional autophagy and poor differentiation. Our recent studies have suggested that the tripartite motif containing-21 (TRIM21) plays a crucial role in regulating OS cell senescence and proliferation via interactions with several proteins. Yet, its implication in autophagy and differentiation in OS is largely unknown. In the present study, we first showed that TRIM21 could promote OS cell autophagy, as determined by the accumulation of LC3-II, and the degradation of cargo receptor p62. Further, we were able to identify that Annexin A2 (ANXA2), as a novel interacting partner of TRIM21, was critical for TIRM21-induced OS cell autophagy. Although TRIM21 had a negligible effect on the mRNA and protein expressions of ANXA2, we did find that TRIM21 facilitated the translocation of ANXA2 toward plasma membrane (PM) in OS cells through a manner relying on TRIM21-mediated cell autophagy. This functional link has been confirmed by observing a nice co-expression of TRIM21 and ANXA2 (at the PM) in the OS tissues. Mechanistically, we demonstrated that TRIM21, via facilitating the ANXA2 trafficking at the PM, enabled to release the transcription factor EB (TFEB, a master regulator of autophagy) from the ANXA2-TFEB complex, which in turn entered into the nucleus for the regulation of OS cell autophagy. In accord with previous findings that autophagy plays a critical role in the control of differentiation, we also demonstrated that autophagy inhibited OS cell differentiation, and that the TRIM21/ANXA2/TFEB axis is implicated in OS cell differentiation through the coordination with autophagy. Taken together, our results suggest that the TRIM21/ANXA2/TFEB axis is involved in OS cell autophagy and subsequent differentiation, indicating that targeting this signaling axis might lead to a new clue for OS treatment.

Factors Affecting Prognosis and Survival in Extremity Osteosarcoma

Background

Osteosarcoma is a malignant bone tumor affecting mainly children and young adults and commonly involves extremities. The aim of this study was to assess the patient-related, tumor-related, and treatment-related factors affecting the overall survival in patients with non-metastatic extremity osteosarcoma.

Methodology

A retrospective, single institutional study of 100 patients with non-metastatic extremity osteosarcoma was done between 2014 and 2019. Age, sex, histologic type, tumor site, use of preoperative chemotherapy and its duration, response to chemotherapy, type of surgery, presence of local recurrence, occurrence of lung metastasis, and survival data were recorded. Survival analysis was done using Kaplan-Meier method. p < 0.05 by log-rank test was considered statistically significant. Statistical data were analyzed using SPSS v.25(IBM).

Results

The median age of presentation was 18 years with male sex preponderance. The most common site of presentation was distal femur, and commonest histological variant was osteoblastic osteosarcoma. Incidence of local recurrence was 9%, and lung metastasis was identified in 12% on follow-up. The 5-year overall survival (OS) was 65.5%, and 5-year local recurrence-free survival was 57.6%. The 5-year OS in neoadjuvant chemotherapy group was 80% compared to 39.5% in upfront surgery group (p = 0.015). The 5-year OS in patients with tumor necrosis > 90% and < 90% was 93.2% and 71.2%, respectively (p = 0.038). The 5-year OS in patients without lung metastasis was 76%, whereas none who developed lung metastasis has survived 5 years (p < 0.001).

Conclusion

The use of neoadjuvant chemotherapy, good response to chemotherapy, and the absence of lung metastasis on follow-up can independently predict better overall survival.

Wnt Signaling in Osteosarcoma

Wnt molecules are a class of cysteine-rich secreted glycoproteins that participate in various developmental events during embryogenesis and adult tissue homeostasis. Since its discovery in 1982, the roles of Wnt signaling have been established in various key regulatory systems in biology. Wnt signals exert pleiotropic effects, including mitogenic stimulation, cell fate specification, and differentiation. The Wnt signaling pathway in humans has been shown to be involved in a wide variety of disorders including colon cancer, sarcoma, coronary artery disease, tetra-amelia, Mullerian duct regression, eye vascular defects, and abnormal bone mass. The canonical Wnt pathway functions by regulating the function of the transcriptional coactivator β-catenin, whereas noncanonical pathways function independent of β-catenin. Although the role of Wnt signaling is well established in epithelial malignancies, its role in mesenchymal tumors is more controversial. Some studies have suggested that Wnt signaling plays a pro-oncogenic role in various sarcomas by driving cell proliferation and motility; however, others have reported that Wnt signaling acts as a tumor suppressor by committing tumor cells to differentiate into a mature lineage. Wnt signaling pathway also plays an important role in regulating cancer stem cell function. In this review, we will discuss Wnt signaling pathway and its role in osteosarcoma.

Enhanced Antiproliferative Effect of Combined Treatment with Calcitriol and All-Trans Retinoic Acid in Relation to Vitamin D Receptor and Retinoic Acid Receptor α Expression in Osteosarcoma Cell Lines

The main objective of this study was to analyze changes in the antiproliferative effect of vitamin D3, in the form of calcitriol and calcidiol, via its combined application with all-trans retinoic acid (ATRA) in osteosarcoma cell lines. The response to treatment with calcitriol and calcidiol alone was specific for each cell line. Nevertheless, we observed an enhanced effect of combined treatment with ATRA and calcitriol in the majority of the cell lines. Although the levels of respective nuclear receptors did not correlate with the sensitivity of cells to these drugs, vitamin D receptor (VDR) upregulation induced by ATRA was found in cell lines that were the most sensitive to the combined treatment. In addition, all these cell lines showed high endogenous levels of retinoic acid receptor α (RARα). Our study confirmed that the combination of calcitriol and ATRA can achieve enhanced antiproliferative effects in human osteosarcoma cell lines in vitro. Moreover, we provide the first evidence that ATRA is able to upregulate VDR expression in human osteosarcoma cells. According to our results, the endogenous levels of RARα and VDR could be used as a predictor of possible synergy between ATRA and calcitriol in osteosarcoma cells.

Mesenchymal stem cell-derived exosomes carrying microRNA-150 suppresses the proliferation and migration of osteosarcoma cells via targeting IGF2BP1

BACKGROUND

MicroRNA-150 (miR-150) plays a critical role in varied types of human cancers. In this study, we explored the effect and mechanism of mesenchymal stem cell (MSC)-derived exosomes (exo) carrying miR-150 (MSC-Exo-150) on the proliferation, migration, invasion, and apoptosis of osteosarcoma (OS) cells.

METHODS

MiR-150 expression in OS cell lines was assessed by quantitative reverse-transcription PCR (qRT-PCR). MSCs were transfected with cell-miR-67 or has-miR-150, and grouped as MSC-67 or MSC-150. Exosomes were isolated from each group, and separately named MSC-Exo-67, MSC-Exo-150 and MSC-Exo. MTT or flow cytometry assay was used to analyze the proliferation or apoptosis of U2SO and HOS cells, respectively. Wound healing or transwell assay was utilized to examine the migration or invasion of U2SO and HOS cells, respectively. The target relationship of miR-150 and insulin-like growth factor 2 mRNA binding protein 1 (IGF2BP1) was established using StarBase2.0 and verified by dual-luciferase reporter gene analysis. Xenografted tumor model was established in rats to confirm the inhibitory effect of MSC-Exo-150 on the growth of xenografted tumor in vivo.

RESULTS

The expression of miR-150 was downregulated in OS cell lines, and significantly higher in MSC-150 cells than that in MSCs. MiR-150 was overexpressed in MSC-Exo-150 group compared with MSC-Exo group. After transfection of MSC-Exo-150 into U2SO and HOS cells, cell viability, mobility and invasion rate were decreased, and the cell apoptosis was increased. MiR-150 targeted IGF2BP1 and IGF2BP1 expression was negatively modulated by miR-150. Overexpression of IGF2BP1 reversed the anti-tumor effect of MSC-Exo-150 on HOS cells.

CONCLUSIONS

MSC-Exo-150 inhibited proliferation, migration, invasion, and induced apoptosis of OS cells by targeting IGF2BP1.

Guideline for Limb-Salvage Treatment of Osteosarcoma

Osteosarcoma is the most common primary malignant bone tumor, occurring mainly in children and adolescents, and the limbs are the main affected sites. At present, limb‐salvage treatment is considered as an effective basic standard treatment for osteosarcoma of the limb. China has a vast territory, but the development of technology is not balanced,which requires sufficient theoretical coverage, strong technical guidance and the application of limb‐salvage treatment guidelines to the treatment of osteosarcoma. Therefore, to standardize and promote the development of limb‐salvage surgery technology and improve the success rate of limb‐salvage treatment, this guide systematically introduces limb‐salvage techniques for the treatment of patients with limb osteosarcoma through definition of limb‐salvage treatment, surgical methods, efficacy evaluation, postoperative treatment and prevention of complications, rehabilitation guidance, and follow‐up advice.