Outcome in dedifferentiated chondrosarcoma for patients treated with multimodal therapy: Results from the EUROpean Bone Over 40 Sarcoma Study

Controversies in orthopaedic oncology

Chondrosarcoma is the second most common surgically treated primary bone sarcoma. Despite a large number of scientific papers in the literature, there is still significant controversy about diagnostics, treatment of the primary tumour, subtypes, and complications. Therefore, consensus on its day-to-day treatment decisions is needed. In January 2024, the Birmingham Orthopaedic Oncology Meeting (BOOM) attempted to gain global consensus from 300 delegates from over 50 countries. The meeting focused on these critical areas and aimed to generate consensus statements based on evidence amalgamation and expert opinion from diverse geographical regions. In parallel, periprosthetic joint infection (PJI) in oncological reconstructions poses unique challenges due to factors such as adjuvant treatments, large exposures, and the complexity of surgery. The meeting debated two-stage revisions, antibiotic prophylaxis, managing acute PJI in patients undergoing chemotherapy, and defining the best strategies for wound management and allograft reconstruction. The objectives of the meeting extended beyond resolving immediate controversies. It sought to foster global collaboration among specialists attending the meeting, and to encourage future research projects to address unsolved dilemmas. By highlighting areas of disagreement and promoting collaborative research endeavours, this initiative aims to enhance treatment standards and potentially improve outcomes for patients globally. This paper sets out some of the controversies and questions that were debated in the meeting.

A Systematic Review of Adjuvant Chemotherapy in Localized Dedifferentiated Chondrosarcoma

Dedifferentiated chondrosarcoma (DDCS) is a high-grade subtype of chondrosarcoma with the bimorphic histological appearance of a conventional chondrosarcoma component with abrupt transition to a high-grade, non-cartilaginous sarcoma. DDCS can be radiographically divided into central and peripheral types. Wide resection is currently the main therapeutic option for localized DDCS. Moreover, the effectiveness of adjuvant chemotherapy remains controversial. Therefore, we performed a systematic review of available evidence to evaluate the effect of adjuvant chemotherapy on localized DDCS. The purpose was to compare the 5-year survival rate among patients treated with surgery plus adjuvant chemotherapy or surgery alone for localized DDCS. The search was conducted in PubMed, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL) databases. Of the 217 studies shortlisted, 11 retrospective non-randomized studies (comprising 556 patients with localized DDCS) were selected. The 5-year survival rates were similar between the two treatment groups (28.2% (51/181) vs. 24.0% (90/375), respectively). The overall pooled odds ratio was 1.25 (95% confidence interval: 0.80-1.94; p = 0.324), and heterogeneity I2 was 2%. However, when limited to peripheral DDCS, adjuvant chemotherapy was associated with prolonged survival (p = 0.03). Due to the paucity of included studies and the absence of prospective comparative studies, no conclusions can be drawn regarding the effectiveness or ineffectiveness of adjuvant chemotherapy for localized DDCS.

Outcome of rare primary malignant bone sarcoma treated with multimodal therapy: Results from the EUROpean Bone Over 40 Sarcoma Study (EURO-B.O.S.S.)

BACKGROUND

Rare primary malignant bone sarcomas (RPMBS) account for 5%-10% of primary high-grade bone tumors and represent a major treatment challenge. The outcome of patients with RPMBS enrolled in the EUROpean Bone Over 40 Sarcoma Study (EURO-B.O.S.S) is presented.

METHODS

Inclusion criteria were as follows: age from 41 to 65 years and a diagnosis of high-grade spindle cell, pleomorphic, or vascular RPMBS. The chemotherapy regimen included doxorubicin 60 mg/m2 , ifosfamide 9 g/m2 , and cisplatin 90 mg/m2 ; postoperative methotrexate 8 g/m2 was added in case of a poor histologic response. Version 2.0 of the Common Terminology Criteria for Adverse Events, Kaplan-Meier curves, log-rank tests, and univariate Cox regression models were used.

RESULTS

In total, 113 patients were evaluable for analysis. The median patient age was 52 years (range, 40-66 years), and 67 patients were men. Eighty-eight tumors were categorized as undifferentiated pleomorphic sarcomas (UPS), 20 were categorized as leiomyosarcomas, three were categorized as fibrosarcomas, and two were categorized as angiosarcomas. Eighty-three of 113 tumors were located in the extremities. Ninety-five of 113 patients presented with no evidence of metastases. After a median follow-up of 6.8 years (interquartile range [IQR], 3.5-9.8 years), the 5-year overall survival rate for patients with localized disease was 68.4% (IQR, 56.9%-77.5%), and it was 71.7% (IQR, 58.1%-81.6%) for patients with UPS and 54.9% (IQR, 29.5%-74.5%) for patients with leiomyosarcoma. Grade III-IV hematologic toxicity was reported in 81% patients; 23% had grade II-III neurotoxicity, and 37.5% had grade I-II nephrotoxicity. Five-year overall survival was significantly better for patients with localized disease, for patients who obtained surgical complete remission, and when the primary tumor was located in the extremities.

CONCLUSIONS

The survival of patients who had RPMBS in the current series was similar to that of age-matched patients who had high-grade osteosarcoma treated according to the same protocol. An osteosarcoma-like chemotherapy may be proposed in patients who have RPMBS.

Establishment and characterization of a novel dedifferentiated chondrosarcoma cell line, SMU-DDCS, harboring an IDH1 mutation

Dedifferentiated chondrosarcoma (DDCS) is a high-grade subtype with a bi-morphic histological appearance of a conventional chondrosarcoma component and it can abruptly transition to a high-grade non-cartilaginous sarcoma. To better understand the biological features of DDCSs and to help develop new therapies, a novel DDCS cell line, SMU-DDCS, was established. Tissue from an open biopsy of a tumor resected from a 75-year-old patient was subjected to primary culture. The cell line was established and authenticated by assessing DNA microsatellite short tandem repeats. The cells maintained in monolayer cultures exhibited constant growth, spheroid formation, and high invasive capacity. Out of the four mice inoculated with SMU-DDCS cells, tumors developed in three mice after 2 weeks. R132C mutation was found in the IDH1 but not the IDH2 genomic DNA sequence of SMU-DDCS cells. SMU-DDCS cells exhibited low chemosensitivity to doxorubicin, methotrexate, and cisplatin. This SMU-DDCS cell line harboring an IDH1 mutation will be a useful tool for investigating DDCS development and for evaluating novel therapeutic agents against it.

Construction of novel predictive tools for post-surgical cancer-specific survival probability in patients with primary chondrosarcoma and external validation in Chinese cohorts: a large population-based retrospective study

BACKGROUND

Surgery is the predominant treatment modality for chondrosarcoma. This study aims to construct a novel clinic predictive tool that accurately predicts the 3-, 5-, and 8-year probability of cancer-specific survival (CSS) for primary chondrosarcoma patients who have undergone surgical treatment.

METHODS

The Surveillance, Epidemiology, and End Results (SEER) database was used to identify 982 primary chondrosarcoma patients after surgery, who were randomly divided into two sets: training set (60%) and internal validation set (40%). Cox proportional regression analyses were used to screen post-surgical independent prognostic variables in primary chondrosarcoma patients. These identified variables were used to construct a nomogram to predict the probability of post-surgical CSS of primary chondrosarcoma patients. The k-fold cross-validation method (k = 10), Harrell's concordance index (C-index), receiver operating characteristic curve (ROC) and area under curve (AUC) were used to assess the predictive accuracy of the nomogram. Calibration curve and decision curve analysis (DCA) were used to validate the clinical application of the nomogram.

RESULTS

Age, tumor size, disease stage and histological type were finally identified post-surgical independent prognostic variables. Based the above variables, a nomogram was constructed to predict the 3-, 5- and 8-year probability of post-surgical CSS in primary chondrosarcoma patients. The results of the C-index showed excellent predictive performance of the nomogram (training set: 0.837, 95% CI: 0.766-0.908; internal validation set: 0.835, 95% CI: 0.733-0.937; external validation set: 0.869, 95% CI: 0.740-0.998). The AUCs of ROC were all greater than 0.830 which again indicated that the nomogram had excellent predictive performance. The results of calibration curve and DCA indicated that the clinical applicability of this nomogram was outstanding. Finally, the risk classification system and online access version of the nomogram was developed.

CONCLUSION

We constructed the first nomogram to accurately predict the 3-, 5- and 8-year probability of post-surgical CSS in primary chondrosarcoma patients. This nomogram would assist surgeons to provide individualized post-surgical survival predictions and clinical strategies for primary chondrosarcoma patients.

IDH mutations in G2-3 conventional central bone chondrosarcoma: a mono institutional experience

BACKGROUND

Heterozygous isocitrate dehydrogenase (IDH) mutations occur in about half of conventional central bone chondrosarcomas (CCBC). Aim of this study was to assess the frequency and prognostic impact of IDH mutations in high grade CCBC patients.

METHODS

64 patients with G2 and G3 CCBC were included. DNA extraction, PCR amplification of IDH1/2 exon 4s, and sequencing analysis with Sanger were performed.

RESULTS

IDH mutations were detected in 24/54 patients (44%): IDH1 in 18, IDH2 in 4, and both IDH1/2 in 2 patients. The frequency of mutations was 37% in G2 vs. 69% in G3 (p = 0.039), and 100% in three Ollier disease associated chondrosarcoma. 5-year overall survival (OS) at 124 months (range 1-166) was 51%, with no significant difference based on the IDH mutational status: 61% in IDHmut vs. 44% in IDH wild type (IDHwt). The 5-year relapse free survival (RFS) was 33% (95% CI:10-57) for IDHmut vs. 57% (95%CI: 30-77) for IDHwt. Progression free survival (PFS) was 25% (95%CI:1-65) IDHmut vs. 16% (95%CI: 0.7-52) IDHwt. 55% (5/9) of IDHmut G2 became higher grade at the recurrence, as compared with 25% (3/12) of G2 IDHwt.

CONCLUSIONS

This study shows a higher frequency of IDH mutations in G3 CCBC as compared with G2. No significant differences in OS, RFS, and PFS by mutational status were detected. After relapse, a higher rate of G3 for IDH mutated CCBC was observed.

Dedifferentiated Chondrosarcoma from Molecular Pathology to Current Treatment and Clinical Trials

Dedifferentiated chondrosarcoma (DDCS) is a rare subtype of chondrosarcoma, a primary cartilaginous malignant neoplasm. It accounts for up to 1-2% of all chondrosarcomas and is generally associated with one of the poorest prognoses among all chondrosarcomas with the highest risk of metastasis. The 5-year survival rates range from 7% to 24%. DDCS may develop at any age, but the average presentation age is over 50. The most common locations are the femur, pelvis humerus, scapula, rib, and tibia. The standard treatment for localised disease is surgical resection. Most patients are diagnosed in unresectable and advanced stages, and chemotherapy for localised and metastatic dedifferentiated DDCS follows protocols used for osteosarcoma.

Establishment, Maintenance, and Performance of the Cooperative Osteosarcoma Study Group (COSS)

INTRODUCTION

Osteosarcoma treatment has benefitted greatly from collaborative research. This paper describes the history and accomplishments of the Cooperative Osteosarcoma Study Group (COSS), mainly dedicated to clinical questions, as well as remaining challenges.

MATERIALS AND METHODS

Narrative review of over four decades of uninterrupted collaboration within the multi-national German-Austrian-Swiss COSS group.

RESULTS

Since its very first prospective osteosarcoma trial starting in 1977, COSS has continuously been able to provide high-level evidence on various tumor- and treatment-related questions. This includes both the cohort of patients enrolled into prospective trials as well as those patients excluded from them for various reasons, followed in a prospective registry. Well over one hundred disease-related publications attest to the group's impact on the field. Despite these accomplishments, challenging problems remain.

DISCUSSION

Collaborative research within a multi-national study group resulted in better definitions of important aspects of the most common bone tumor, osteosarcoma, and its treatments. Important challenges continue to persist.

Appendicular dedifferentiated chondrosarcoma: A management and survival study from the SEER database

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Dedifferentiated chondrosarcoma is an aggressive bone tumor with high rates of metastasis that severely impact the patient’s prognosis.

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Treatment usually consists of either a limb-salvage procedure or limb amputation, the former being more commonly performed.

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Size of the tumor severely impacts the likelihood of presenting metastasis at diagnosis.

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Female gender appears to be an important protective factor against death.

Introduction

Dedifferentiated chondrosarcoma (DDC) is an aggressive osseous neoplasm with a dismal prognosis. Treatment commonly involves limb-salvage surgery or amputation. In patients with appendicular DDC, we sought to describe demographic, clinical and treatment characteristics (1), analyze risk factors for metastasis (2) and overall death (3), and assess survival rates by treatment (4).

Materials and methods

Two-hundred-and-five patients from the SEER Database were included in our analysis. Demographic, clinical and treatment variables were analyzed. Multivariate regression was performed to identify risk factors. Survival analysis was performed using the Kaplan-Meier method.

Results

Fifty-one (24.9 %) of the patients included presented metastasis at diagnosis. The most common locations were the lungs, other sites, and bone. Surgery to the primary site was more common in patients without metastasis (94.2 %) than those with (78.2 %); limb-salvage procedures were more common than amputations. Tumors >8 cm (T2) and those discontinuous (T3) were more likely to present metastasis at diagnosis (OR = 2.54, p = 0.043 and OR = 7.4, p = 0.008, respectively). Female gender was found to be a protective factor for overall death on crude analysis (OR = 0.33, p = 0.019). Metastases to sites other than the lungs (M1b) had the highest risk of overall death (OR = 49, p = 0.01). Combination of surgery and chemotherapy showed a trend towards higher overall survival in non-metastatic patients (p = 0.1069 and p = 0.1703).

Conclusions

Appendicular DDC displays a high metastatic rate and low survival rates. The most common procedure is a limb-salvage surgery. Tumor size increases the risk of presenting metastases at diagnosis and female gender is a protective factor against death.

Systemic treatment for primary malignant sarcomas arising in craniofacial bones

Introduction

Craniofacial bones may be the site of origin of various sarcomas. We review the various malignancies affecting this region of the body and attempt to put systemic treatment approaches into perspective.

Material and methods

Non-systematic literature review

Results

Conventional types of osteosarcoma, Ewing sarcoma, and chondrosarcoma are the most frequent bone sarcomas occurring in craniofacial region, but variants may occur. The tumors’ biologies and the resulting treatment strategies vary distinctly. As a general rule, local control remains paramount regardless of histology. The efficacy of antineoplastic chemotherapy varies by type of malignancy. It is clearly indicated in Ewing sarcoma and related tumors, potentially of benefit in high-grade osteosarcoma, undifferentiated pleomorphic sarcoma, dedifferentiated and mesenchymal chondrosarcoma, and of no proven benefit in the others.

Conclusions

Various histologies demand various and distinct treatment approaches, with local control remaining paramount in all. The efficacy of systemic treatments varies by type of tumor. Prospective trials would help in all of these to better define systemic treatment strategies.

Surgical Treatment of Bone Sarcoma

Bone sarcomas are rare primary malignant mesenchymal bone tumors. The three main entities are osteosarcoma, chondrosarcoma, and Ewing sarcoma. While prognosis has improved for affected patients over the past decades, bone sarcomas are still critical conditions that require an interdisciplinary diagnostic and therapeutic approach. While radiotherapy plays a role especially in Ewing sarcoma and chemotherapy in Ewing sarcoma and osteosarcoma, surgery remains the main pillar of treatment in all three entities. After complete tumor resection, the created bone defects need to be reconstructed. Possible strategies are implantation of allografts or autografts including vascularized bone grafts (e.g., of the fibula). Around the knee joint, rotationplasty can be performed or, as an alternative, the implantation of (expandable) megaprostheses can be performed. Challenges still associated with the implantation of foreign materials are aseptic loosening and infection. Future improvements may come with advances in 3D printing of individualized resection blades/implants, thus also securing safe tumor resection margins while at the same time shortening the required surgical time. Faster osseointegration and lower infection rates may possibly be achieved through more elaborate implant surface structures.

Management of Primary Aggressive Tumors of the Knee

Primary bone sarcomas and aggressive benign bone tumors are relatively rare. It is essential to recognize features that are concerning for these aggressive tumors based on a patient's history, physical exam, and radiographs. Physicians and other health care providers should have a high suspicion for these tumors and promptly refer these patients to orthopaedic oncologists. A multidisciplinary, team-based approach is required to obtain an accurate diagnosis and provide comprehensive care. This review discussed the appropriate work-up, biopsy principles, relevant peri-operative medical management, and surgical treatment options for patients with aggressive primary bone tumors around the knee. Primary bone sarcomas (osteosarcoma and chondrosarcoma) and aggressive benign bone tumors (giant cell tumor, chondroblastoma, and chondromyxoid fibroma) that have a predilection to the distal femur and proximal tibia are the focus of this review.

Clinical features and treatment outcomes of dedifferentiated and grade 3 chondrosarcoma: A multi-institutional study

Chondrosarcoma is the second most common primary malignant bone tumor. In this multicenter study, we sought to evaluate the (i) disease-specific survival (DSS) and disease-free survival (DFS), and (ii) prognostic factors in patients with dedifferentiated chondrosarcoma (DDCS) and grade 3 chondrosarcoma (G3CS) in Japan. We retrospectively investigated the treatment outcomes and prognostic factors in 62 patients with DDCS and 19 patients with G3CS at 15 institutions participating in the Japanese Musculoskeletal Oncology Group. We also clarified significant clinico-pathological factors for oncological outcomes. In surgery for primary lesions aimed at cure, a histologically negative margin (R0) was obtained in 93% (14/15) of patients with G3CS and 100% (49/49) of patients with DDCS. The 5-year DSS was 18.5% in patients with DDCS and 41.7% in patients with G3CS (P = 0.13). Local control was obtained in 80% (12/15) and 79.6% (39/49) of patients with G3CS and DDCS in the primary lesion after surgery with a wide surgical margin, respectively. In multivariate analysis, stage and no treatment/palliative treatment for the primary lesion were independent prognostic factors for DSS of DDCS, age and no treatment/palliative treatment for DSS of G3CS. The 5-year DFS rate was 22.8% in 26 patients with DDCS who did not receive adjuvant chemotherapy, and 21.4% in 14 patients who received adjuvant chemotherapy. The prognosis of DDCS remains poor, although R0 resection was performed in most cases. Effective and/or intensive chemotherapeutic regimens or agents should be considered or developed for patients with high-grade chondrosarcoma, particularly for those with DDCS.

Is Chemotherapy Associated with Improved Overall Survival in Patients with Dedifferentiated Chondrosarcoma? A SEER Database Analysis

BACKGROUND

Dedifferentiated chondrosarcoma is a chondrosarcoma subtype associated with high rates of recurrence and a poor prognosis. Others have proposed treatment of dedifferentiated chondrosarcoma using osteosarcoma protocols, including perioperative chemotherapy. However, the rarity of this condition poses difficulties in undertaking single- institution studies of sufficient sample size.

QUESTION/PURPOSE

Is perioperative chemotherapy associated with improved overall survival in patients with dedifferentiated chondrosarcoma?

METHODS

We queried the Surveillance, Epidemiology, and End Results (SEER) 1973 to 2016 database for patients with a diagnosis of dedifferentiated chondrosarcoma (n = 308). As dedifferentiated chondrosarcoma was only classified as a distinct entity in SEER starting in 2000, only patients treated in 2000 and later were included. We excluded from our analyses those patients with distant disease at diagnosis, a primary site of disease other than bone or joints, and those who did not receive cancer-directed surgery. These criteria yielded 185 dedifferentiated chondrosarcoma patients for inclusion. We used Kaplan-Meier analyses and Cox proportional hazards models to assess the association of clinical, demographic, and treatment characteristics on overall survival (OS).

RESULTS

After controlling for confounding variables, including age, sex, tumor size, stage, grade, location, and radiation treatment status, and after adjusting for missing data, no overall survival benefit was associated with receipt of chemotherapy in patients with dedifferentiated chondrosarcoma (hazard ratio 0.75 [95% confidence interval 0.49 to 1.12]; p = 0.16).

CONCLUSION

Chemotherapy treatment of dedifferentiated chondrosarcoma was not associated with improved OS. These results must be viewed cautiously, given the limited granularity of information on chemotherapy treatment, the concerns regarding chemotherapy misclassification in SEER data, and the small sample of patients with dedifferentiated chondrosarcoma, all of which limit the power to detect a difference. Our findings are nevertheless consistent with those of prior reports in which no benefit of chemotherapy could be detected. Lack of clear benefit from perioperative chemotherapy in dedifferentiated chondrosarcoma argues that it should be used only after careful consideration, and ideally in the context of a clinical trial.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Challenges of Systemic Therapy Investigations for Bone Sarcomas

Bone sarcoma is a rare component of malignant solid tumors that accounts for only ~0.2% of malignancies. Bone sarcomas present various histological types, and genomic mutations differ markedly by the histological types. Although there are vast mutations in various bone sarcomas, most of them are non-actionable, and even potential targetable mutations that are actionable targets in other malignancies have not shown the appropriate responses in clinical trials for bone sarcomas. Investigations of new systemic therapy, including molecular targeted therapies for bone sarcomas, have thus not progressed like those for other solid tumors. Another problem is that high rates of pediatric/adolescent and young adult patients have bone sarcomas such as osteosarcoma, and patient recruitment for clinical trials (especially randomized trials) is challenging. For pediatric patients, evaluations of tolerability and appropriate dose modifications of new drugs are needed, as their findings could provide the threshold for investigating new drugs for bone sarcomas. To solve these problems, improvements in registry systems, real world data, and pediatric extrapolation have been attempted. We review the issues regarding targeted drug investigations for bone sarcomas, focusing on the current clinical evidence and efforts to resolve these issues.

Dedifferentiated chondrosarcoma: current standards of care

Dedifferentiated chondrosarcomas are aggressive variants of chondrosarcoma, associated with poor outcomes. Tumor biphasism is the norm. The majority of these tumors are symptomatic at presentation. Radiologically, large soft tissue masses with bony destruction predominate. Treatment protocols of these tumors are not well defined. Surgical resection forms the standard of care for localized disease. (Neo)adjuvant therapies remain controversial as the results from multiple (mainly retrospective) studies remain conflicting. Age at presentation, stage and ability to obtain negative resection margins are important prognostic factors. The overall prognosis is dismal. Newer and novel therapies targeting the complex genetic makeup of these tumors have renewed interest in the adjuvant setting that could hold promise in the near future.