The role of FDG PET/CT in patients treated with neoadjuvant chemotherapy for localized bone sarcomas

Clinical practice guidelines for the treatment of Ewing sarcoma (Spanish Sarcoma Research Group-GEIS)

Ewing sarcoma is a small round-cell sarcoma characterized by gene fusion involving EWSR1 (or another TET family protein like FUS) and an ETS family transcription factor. The estimated incidence of this rare bone tumor, which occurs most frequently in adolescents and young adults, is 0.3 per 100,000/year. Although only 25% of patients with Ewing sarcoma are diagnosed with metastatic disease, historical series show that this is a systemic disease. Patient management requires multimodal therapies-including intensive chemotherapy-in addition to local treatments (surgery and/or radiotherapy). In the recurrent/refractory disease setting, different approaches involving systemic treatments and local therapies are also recommended as well as patient inclusion in clinical trials whenever possible. Because of the complexity of Ewing sarcoma diagnosis and treatment, it should be carried out in specialized centers and treatment plans should be designed upfront by a multidisciplinary tumor board. These guidelines provide recommendations for diagnosis, staging, and multimodal treatment of Ewing sarcoma.

A bibliometric analysis based on hotspots and frontier trends of positron emission tomography/computed tomography utility in bone and soft tissue sarcoma

Purpose

This study aimed to analyze articles on the diagnosis and treatment of bone and soft tissue sarcoma using positron emission tomography (PET)/computed tomography (CT) published in the last 13 years. The objective was to conduct a bibliometric analysis and identify the research hotspots and emerging trends.

Methods

Web of Science was used to search for articles on PET/CT diagnosis and treatment of bone and soft tissue sarcoma published from January 2010 to June 2023. CiteSpace was utilized to import data for bibliometric analysis.

Results

In total, 425 relevant publications were identified. Publications have maintained a relatively stable growth rate for the past 13 years. The USA has the highest number of published articles (139) and the highest centrality (0.35). The UDICE-French Research Universities group is the most influential institution. BYUN BH is a prominent contributor to this field. The Journal of Clinical Oncology has the highest impact factor in the field.

Conclusion

The clinical application of PET/CT is currently a research hotspot. Upcoming areas of study concentrate on the merging of PET/CT with advanced machine learning and/or alternative imaging methods, novel imaging substances, and the fusion of diagnosis and therapy. The use of PET/CT has progressively become a crucial element in the identification and management of sarcomas. To confirm its efficacy, there is a need for extensive, multicenter, prospective studies.

A reduction in tumor volume exceeding 65% predicts a good histological response to neoadjuvant chemotherapy in patients with Ewing sarcoma

OBJECTIVE

No consensus exists for tumor volume response criteria in patients with Ewing sarcoma. This study aimed to identify an optimal cutoff for predicting a good histological response by analyzing tumor volume changes and tumor necrosis after neoadjuvant chemotherapy.

MATERIALS AND METHODS

We performed a retrospective analysis of 184 Ewing sarcoma patients, analyzing tumor volume changes before and after neoadjuvant chemotherapy. Patients were divided into two groups based on histological response: good (tumor necrosis ≥ 95%) and poor (tumor necrosis < 95%) responders. The receiver operating characteristic (ROC) area under the curve (AUC) method was used to determine the optimal thresholds for predicting the histological response. Additionally, the prognostic value of this cutoff for relapse-free survival was assessed.

RESULTS

Out of 184 patients, 83 (45%) had tumor necrosis ≥ 95%, while 101 (55%) had tumor necrosis < 95%. ROC analysis identified the optimal cutoff for a good histological response as over 65% tumor volume reduction (AUC = 0.69; p < 0.001). Patients with volume reduction of ≥ 65% had a higher likelihood of a good histological response than those with lesser reductions (p = 0.004; odds ratio = 2.61). Multivariable analysis indicated a correlation between poor histological response and reduced relapse-free survival (hazard ratio = 2.17; p = 0.01), while tumor volume reduction itself did not impact survival.

CONCLUSION

We reported that a tumor volume reduction of ≥ 65% was able to predict a good histological response in Ewing sarcoma patients. We recommend preoperative tumor volume assessment to identify patients at greater risk for poor histological response who could benefit from more intensive chemotherapy protocols or additional radiotherapy.

Can FDG-PET assess the response to chemotherapy and predict tissue necrosis in osteosarcoma and Ewing sarcoma?

INTRODUCTION

Osteosarcoma (OS) and Ewing sarcoma (ES) represent the pediatric population's most common malignant bone tumors. 18-Fluorodeoxyglucose positron emission tomography has been shown to be effective in both the diagnostic and staging phases of cancer treatment. In recent years, some studies have also explored the possibility that FDG-PET could have a prognostic role.

Evaluation of response to neoadjuvant chemotherapy in osteosarcoma using dynamic contrast-enhanced MRI: development and external validation of a model

OBJECTIVE

To identify which dynamic contrast-enhanced (DCE-)MRI features best predict histological response to neoadjuvant chemotherapy in patients with an osteosarcoma.

METHODS

Patients with osteosarcoma who underwent DCE-MRI before and after neoadjuvant chemotherapy prior to resection were retrospectively included at two different centers. Data from the center with the larger cohort (training cohort) was used to identify which method for region-of-interest selection (whole slab or focal area method) and which change in DCE-MRI features (time to enhancement, wash-in rate, maximum relative enhancement and area under the curve) gave the most accurate prediction of histological response. Models were created using logistic regression and cross-validated. The most accurate model was then externally validated using data from the other center (test cohort).

RESULTS

Fifty-five (27 poor response) and 30 (19 poor response) patients were included in training and test cohorts, respectively. Intraclass correlation coefficient of relative DCE-MRI features ranged 0.81-0.97 with the whole slab and 0.57-0.85 with the focal area segmentation method. Poor histological response was best predicted with the whole slab segmentation method using a single feature threshold, relative wash-in rate <2.3. Mean accuracy was 0.85 (95%CI: 0.75-0.95), and area under the receiver operating characteristic curve (AUC-index) was 0.93 (95%CI: 0.86-1.00). In external validation, accuracy and AUC-index were 0.80 and 0.80.

CONCLUSION

In this study, a relative wash-in rate of <2.3 determined with the whole slab segmentation method predicted histological response to neoadjuvant chemotherapy in osteosarcoma. Consistent performance was observed in an external test cohort.

NTRK rearranged sarcoma of the bone. Role for larotrectinib in the neoadjuvant setting of an ultra-rare tumor: a case report

BACKGROUND

Neurotrophic tyrosine receptor kinase (NTRK) gene-fusion targeted molecules revolutionized the paradigm of treatment of a limited subgroup of cancers of various histologies. Entrectinib and larotrectinib obtained unprecedented response rates in patients with cancer harboring NTRK rearrangements. This evidence recently led to the agnostic approval of these drugs, and evidence (confirmation) of their activity in a broader disease setting is emerging. Here, we report the case of a patient affected by EML4-NTRK3 rearranged undifferentiated spindle cell bone sarcoma treated with larotrectinib, and we argue (discuss about) the incidence and clinical presentation of NTRK gene-fusion positive bone sarcomas, the potential use of upfront treatment with NTRK inhibitors in neoadjuvant setting, and the role of a multidisciplinary tumor board. Despite the rarity of these rearrangements in patients with primitive bone sarcomas, the therapy with NTRK inhibitors represents a highly effective strategy to be pursued in selected cases even in neoadjuvant settings. The management of these very rare cancers should always be discussed in a multidisciplinary board of reference centers.

Guideline and Implementation of Osteosarcoma Nursing Care for Children and Adolescents

Clinical trials on pediatric oncology use therapeutic techniques with the overwhelming majority of children's cancer patients obtaining therapy via clinical investigation procedures. Medical treatment is scheduled according to a specific protocol for enrolled patients. These protocols often do not refer to nursing care. Nursing care, on the other hand, must complement the medical care specified in the medical research protocol. Safe treatment administration, assessment of treatment responses, patients' and families' education, and communication with the whole medical team are just a few of the critical nursing tasks that should be properly managed. Nursing care standards have been developed in this study to strike a good balance between the procedure for clinical research and the nursing care connected with it. These recommendations outline the nursing activities and considerations that must be made while caring for pediatric cancer patients who are engaged in a specific clinical investigation procedure. The objective of this study is to outline the procedure through which nursing care guidelines could be developed and evaluated. The goal of this study was to find out the involvement of nurses in the process of health education for osteosarcoma and family patients.

Prognostic value of fluorodeoxyglucose positron emission tomography derived metabolic parameters and textural features in pediatric sarcoma

PURPOSE

The aim of this study was to evaluate the prognostic value of PET-derived metabolic features and textural parameters of primary tumors in pediatric sarcoma patients.

METHODS

The imaging findings of 43 patients (14 girls and 29 boys; age 11.4 ± 4.4 years) who underwent 18-fluorodeoxyglucose positron emission tomography (PET)/computed tomography for primary staging prior to therapy between 2005 and 2020 were retrospectively evaluated. The diagnoses were osteosarcoma in 10, rhabdomyosarcoma in 10, and Ewing sarcoma in 23 patients. PET metabolic data and textural features of primary tumors were obtained. Cox proportional hazards regression models were used to identify predictors for progression-free survival and overall survival. Survival curves were estimated by using the Kaplan-Meier method.

RESULTS

Distant metastases were detected in primary staging in 13 patients (30.2%). The median follow-up duration after diagnosis was 28 months (range: 10-171 months). In multivariate Cox regression analysis, the presence of distant metastasis and neighborhood grey-level difference matrix_Contrast (ngldm_Contrast) were found as independent predictors for both progression-free survival and overall survival. Grey-level zone length matrix_Zone-length nonuniformity (glzlm_ZLNU) was also found as an independent predictor for overall survival. The Kaplan-Meier survival analysis showed that higher ngldm_Contrast and glzlm_ZLNU values of primary tumors were significantly associated with shorter progression-free survival and overall survival.

CONCLUSION

In addition to the presence of distant metastasis at initial diagnosis, textural features of primary tumors may be used as prognostic biomarkers to identify patients with worse prognosis in pediatric sarcoma. Higher tumor heterogeneity is significantly associated with shorter progression-free survival and OS.

An evaluation of the response to neoadjuvant chemotherapy for osteosarcoma of extremities: PERCIST versus RECIST 1.1 criteria after long-term follow-up

OBJECTIVE

The aim of this study was to compare the recent Positron emission tomography (PET) Response Criteria in Solid Tumors (PERCIST) and Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 criteria for evaluating the response of osteosarcoma to neoadjuvant chemotherapy of the extremities.

METHODS

We retrospectively reviewed patients with osteosarcoma of the extremities who received neoadjuvant chemotherapy and then surgical resection at Peking University People's Hospital. Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) and magnetic resonance imaging (MRI) were performed prior to chemotherapy and before surgical resection. Therapeutic response was assessed separately by the PERCIST and RECIST 1.1 criteria. The association between the data acquired by the PERCIST and RECIST 1.1 criteria was then analyzed by Wilcoxon's signed-rank test. The association between the PERCIST criteria and the pathological necrosis rate was analyzed by Fisher's exact test. Finally, the impact of a range of clinicopathological factors on overall survival (OS) and event-free survival (EFS) was analyzed by Cox proportional hazards regression.

RESULTS

We recruited 68 patients with a median follow-up of 74 months (range 45-102 months). The evaluations resulting from the RECIST 1.1 and PERCIST criteria were significantly different (p = 0.000). Only two responders were identified according to the RECIST 1.1 criteria. However, 34 responders were identified by the PERCIST criteria. Data arising from the PERCIST criteria were in accordance with the pathological necrosis rate. Survival analysis showed that metastasis at diagnosis, poor pathological response, and disease progression (according to the RECIST 1.1 or PERCIST criteria) were all associated with a poor prognosis (p < 0.05).

CONCLUSION

Our data indicate that the PERCIST criteria are significantly more sensitive than RECIST 1.1 criteria to identify more responders when evaluating the response of osteosarcoma to neoadjuvant chemotherapy.

Clinical Perspectives for 18F-FDG PET Imaging in Pediatric Oncology: Μetabolic Tumor Volume and Radiomics

Pediatric cancer, although rare, requires the most optimized treatment approach to obtain high survival rates and minimize serious long-term side effects in early adulthood. 18F-FDG PET/CT is most helpful and widely used in staging, recurrence detection, and response assessment in pediatric oncology. The well-known 18F-FDG PET metabolic indices of metabolic tumor volume (MTV) and tumor lesion glycolysis (TLG) have already revealed an independent significant prognostic value for survival in oncologic patients, although the corresponding cut-off values remain study-dependent and not validated for use in clinical practice. Advanced tumor “radiomic” analysis sheds new light into these indices. Numerous patterns of texture 18F-FDG uptake features can be extracted from segmented PET tumor images due to new powerful computational systems supporting complex “deep learning” algorithms. This high number of “quantitative” tumor imaging data, although not decrypted in their majority and once standardized for the different imaging systems and segmentation methods, could be used for the development of new “clinical” models for specific cancer types and, more interestingly, for specific age groups. In addition, data from novel techniques of tumor genome analysis could reveal new genes as biomarkers for prognosis and/or targeted therapies in childhood malignancies. Therefore, this ever-growing information of “radiogenomics”, in which the underlying tumor “genetic profile” could be expressed in the tumor-imaging signature of “radiomics”, possibly represents the next model for precision medicine in pediatric cancer management. This paper reviews 18F-FDG PET image segmentation methods as applied to pediatric sarcomas and lymphomas and summarizes reported findings on the values of metabolic and radiomic features in the assessment of these pediatric tumors.

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.

The Role of FDG-PET and Whole-Body MRI in High Grade Bone Sarcomas With Particular Focus on Osteosarcoma

Sarcoma represents less than 2% of adult malignancies and about 15% to 20% of malignancies in children and adolescents/young adults. This neoplasm accounts for more than 80 different clinico-pathological entities with different clinical behavior; osteosarcoma and ewing sarcoma are the most frequent primary bone tumors. Because of the general poor prognosis, it is important to find out as many prognostic factors as possible to choose the best therapeutical approach and to correctly schedule the follow-up examinations. Third level imaging such as MRI and PET/CT are of utmost importance in the evaluation of sarcoma patients. The spine and bones in general are optimal sites to be evaluated with FDG PET/CT since the physiological background is low. The standardized uptake value (SUV max, a semiquantitave parameter) is used as a surrogate for proliferative cell rate, and the spatial heterogeneity of FDG distribution within the primary mass as a surrogate for malignancy. In several studies SUVmax was a predictive value for overall survival and progression-free survival. Whole-body MRI is a well-established technique for systemic, radiation-free evaluation, which is mostly applied in the oncological field. WB-MRI provides a combination of anatomical and functional sequences and is useful specifically in the evaluation of disease in organs with relatively high background activity such as the brain, liver, kidney, and spinal canal. These technologies provide accurate staging (also useful to drive the biopsy towards the most active foci in large heterogeneous masses), therapy assessment, relapse detection of local recurrence and distance metastasis but also prognostic indexes, in the context of whole body diagnostic procedures. This paper will provide an overview of the role and added value of PET/CT and WB-MRI in bone sarcomas particular focus on osteosarcoma. We also analyzed the role of the PET/CT and MRI for target delineation of radiation therapy and we and we will do an analysis of future prospects as new tracer non FDG.

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.

Targeted and immuno-based therapies in sarcoma: mechanisms and advances in clinical trials

Sarcomas represent a distinct group of rare malignant tumors with high heterogeneity. Limited options with clinical efficacy for the metastatic or local advanced sarcoma existed despite standard therapy. Recently, targeted therapy according to the molecular and genetic phenotype of individual sarcoma is a promising option. Among these drugs, anti-angiogenesis therapy achieved favorable efficacy in sarcomas. Inhibitors targeting cyclin-dependent kinase 4/6, poly-ADP-ribose polymerase, insulin-like growth factor-1 receptor, mTOR, NTRK, metabolisms, and epigenetic drugs are under clinical evaluation for sarcomas bearing the corresponding signals. Immunotherapy represents a promising and favorable method in advanced solid tumors. However, most sarcomas are immune "cold" tumors, with only alveolar soft part sarcoma and undifferentiated pleomorphic sarcoma respond to immune checkpoint inhibitors. Cellular therapies with TCR-engineered T cells, chimeric antigen receptor T cells, tumor infiltrating lymphocytes, and nature killer cells transfer show therapeutic potential. Identifying tumor-specific antigens and exploring immune modulation factors arguing the efficacy of these immunotherapies are the current challenges. This review focuses on the mechanisms, advances, and potential strategies of targeted and immune-based therapies in sarcomas.

Is It Time to Call Time on Bone Marrow Biopsy for Staging Ewing Sarcoma (ES)?

Simple Summary

Ewing sarcoma (ES) is a rare primary bone cancer, usually found in children and adolescents, which can spread to the lungs, other bones and less commonly, the bone marrow. An accurate determination of the disease spread at baseline (staging) is important to establish prognosis, monitor treatment response and help with management decisions. There is no standard of care for staging ES, although the invasive bone marrow biopsy has traditionally been used to establish whether patients have bone marrow infiltration. Imaging techniques, including FDG-PET/CT and whole-body MRI (WB-MRI), have become established in staging other cancers with expanding use for staging ES. A number of studies have validated the accuracy, sensitivity and specificity of these modalities for detecting bone and bone marrow metastases in ES. The main aim of this review was to examine the current literature for the use of FDG-PET/CT and WB-MRI in staging ES to determine whether a bone marrow biopsy is still needed and would influence the management of patients. Hereafter, a new staging algorithm for ES recommends WB-MRI and/or FDG-PET/CT without bone marrow biopsy as the standard of care for staging localised and metastatic ES.

Abstract

Primary malignant bone sarcomas are rare and Ewing sarcoma (ES), along with osteosarcoma, predominates in teenagers and young adults. The well-established multimodality treatment incorporates systemic chemotherapy with local control in the form of surgery, with or without radiation. The presence and extent of metastases at diagnosis remains the most important prognostic factor in determining patient outcome; patients with skeletal metastases or bone marrow infiltration having a significantly worse outcome than those with lung metastases alone. There is, however, no accepted staging algorithm for ES. Large cooperative groups and national guidelines continue to advocate bone marrow biopsy (BMB) for staging but functional imaging techniques, such as 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) with computerised tomography (CT) have been increasingly used for staging cancers and whole-body magnetic resonance imaging (WB-MRI) for staging skeletal metastases. This review outlines the current literature, from which we conclude that BMB is no longer required for the staging of ES as it does not influence the standard of care management. BMB may, however, provide prognostic information and insights into the biology of ES in selected patients on prospective clinical trials.

Intraabdominal lesser sac metastasis from Ewing's sarcoma: An exceptional localization

Ewing's sarcoma/primitive neuroectodermal tumor is rare and aggressive with a poor prognosis. Intraabdominal metastases are an uncommon condition. Metastasis in the lesser sac is an exceptional occurrence. To the best of our knowledge, this location has not been described previously. We report a case of a 15-year-old patient treated for Ewing's sarcoma of the left arm 6 years back. She had developed a suspicious mass in the lesser sac 6 years following her primary tumor. The histopathologic exam revealed a tumor with "small round cells" that were positive for CD99, confirming the relapse of Ewing's sarcoma. The relapse was successfully managed with chemotherapy and surgery. Intraabdominal, extraintestinal masses in patients treated previously for Ewing's sarcoma should be considered as Ewing's sarcoma relapse in the differential diagnosis. We fully describe the management of this atypical relapse, with different components of clinical, radiological, and histological findings.

[18F]FDG PET/CT quantitative parameters for the prediction of histological response to induction chemotherapy and clinical outcome in patients with localised bone and soft-tissue Ewing sarcoma

OBJECTIVE

The application of [¹⁸F]FDG PET/CT in predicting histologic response to induction chemotherapy in patients with Ewing sarcoma (EWS) has been proposed using the values of pre-post treatment SUV_max as a referral parameter, although with heterogeneous results. The aim of this retrospective study was to evaluate the diagnostic accuracy of [¹⁸F]FDG PET/CT volumetric parameters (metabolic tumour volume (MTV) and total lesion glycolysis (TLG)) as compared to SUV_max to predict response to chemotherapy and clinical outcome in patients with localised EWS of bone and soft-tissue.

METHODS

Twenty-eight patients with non-metastatic EWS of bone (n = 20) and soft tissues (n = 8) who underwent a [¹⁸F]FDG PET/CT scan before (PET₁) and after induction chemotherapy (PET₂) were enclosed in the analysis. Values of PET metrics (SUV_max, MTV, TLG) at diagnosis and after neoadjuvant chemotherapy as well as the percentage change between PET₁ and PET₂ (ΔSUV, ΔMTV and ΔTLG) were correlated to histological response and to progression-free survival (PFS).

RESULTS

ΔTLG (cut-off: -60%) is the best predictor for histologic response with 100% sensitivity and 77.8% specificity. MTV₁ > 33.4 cm³ and TLG₁ > 112 were also associated with a favourable histologic response (sensitivity 80% and specificity 77.8% for both). On multivariate analysis, SUV₂ (> 3.3) and ΔTLG (< -18%) were independent predictors of worse PFS.

CONCLUSIONS

[¹⁸F]FDG PET/CT could accurately predict histologic response to neoadjuvant chemotherapy in patients with EWS, also showing a possible prognostic value for future disease relapse.

KEY POINTS

• The variation of the PET parameter tumour lesion glycolysis (TLG) can predict the histologic response to induction chemotherapy (sensitivity 100%, specificity 77.8%), in patients with Ewing sarcoma. • The percentage variation of TLG and the value of the SUVmax at PET scan after chemotherapy show a prognostic role for future disease relapse. The combination of both the parameters identifies three prognostic classes of patients with low, intermediate and high risk of disease relapse.

Personalising sarcoma care using quantitative multimodality imaging for response assessment

Over the last decades, technological developments in the field of radiology have resulted in a widespread use of imaging for personalising medicine in oncology, including patients with a sarcoma. New scanner hardware, imaging protocols, image reconstruction algorithms, radiotracers, and contrast media, enabled the assessment of the physical and biological properties of tumours associated with response to treatment. In this context, medical imaging has the potential to select sarcoma patients who do not benefit from (neo-)adjuvant treatment and facilitate treatment adaptation. Due to the biological heterogeneity in sarcomas, the challenge at hand is to acquire a practicable set of imaging features for specific sarcoma subtypes, allowing response assessment. This review provides a comprehensive overview of available clinical data on imaging-based response monitoring in sarcoma patients and future research directions. Eventually, it is expected that imaging-based response monitoring will help to achieve successful modification of (neo)adjuvant treatments and improve clinical care for these patients.

Rare Primary Malignant Bone Sarcomas

Simple Summary

Primary malignant bone tumors are infrequent cancers. More than 90% of these neoplasms are classified as osteosarcomas, Ewing sarcomas or chondrosarcomas, and their clinical presentation, diagnosis, and treatment principles are well-established. The entities described in this article, are ultra-rare varieties of bone sarcomas, and there clinical and histological characteristics are not well known. Therefore, they are very difficult to be diagnosed and there is a lot of uncertainty on their treatment. Because of their rarity, it is also extremely difficult to perform clinical research on these cancers. This article creates more awareness of these very rare bone tumors. It explains how to recognize and diagnose each entity and it summarizes the medical scientific literature that is available on these cancers. Increasing awareness and clinical research for these cancers are key elements to improve the prognosis for patients with these diseases in the long term.

Abstract

Rare primary malignant bone sarcomas (RPMBS), other than osteosarcoma, chondrosarcoma, chordoma, and Ewing sarcoma, account for about 5–10% of primary bone tumors and represent a major diagnostic challenge. These tumors include spindle cell and round cell sarcoma entities, hemangiopericytoma-like and vascular tumors. Additionally, several histotypes, traditionally described in the soft tissues, such as myxofibrosarcoma, synovial sarcoma, and malignant peripheral nerve sheath tumor of bone, have been reported in patients with primary bone tumors. While wide surgical resection is the mainstay of local treatment, systemic therapy of these rare entities is controversial. Patients with undifferentiated spindle cell or pleomorphic high-grade tumors of bone, are usually treated with osteosarcoma-like chemotherapy, while patients with round cell and undifferentiated round cell tumors (URCTs), may respond to sarcoma treatment regimens for Ewing sarcoma patients. Studies on analogies and differences among these ultra-rare tumors have seldom been reported. This review describes relevance, clinical aspects, diagnostic procedures, staging, treatment recommendations, and current research in this composite tumor group.

[18F]FDG PET/CT for evaluating early response to neoadjuvant chemotherapy in pediatric patients with sarcoma: a prospective single-center trial

INTRODUCTION

This is a prospective, single-center trial in pediatric patients with sarcoma aiming to evaluate [¹⁸F]FDG PET/CT as a tool for early response assessment to neoadjuvant chemotherapy (neo-CTX).

METHODS

Bone or soft tissue sarcoma patients with (1) baseline [¹⁸F]FDG PET/CT within 4 weeks prior to the start of neo-CTX (PET1), (2) early interim [¹⁸F]FDG PET/CT (6 weeks after the start of neo-CTX (PET2), (3) evaluation of neo-CTX response by histology or MRI, and (4) definitive therapy after neo-CTX (surgery or radiation) were included. Semiquantitative PET parameters (SUVmax, SUVmean, SUVpeak, MTV and TLG) and their changes from PET1 to PET2 (ΔPET) were obtained. The primary endpoint was to evaluate the predictive value of PET1, PET2 and ΔPET parameters for overall survival (OS) and time to progression (TTP). The secondary outcome was to evaluate if [¹⁸F]FDG PET/CT can predict the response to neo-CTX assessed by histopathology or MRI. Primary and secondary outcomes were also evaluated in a subpopulation of patients with bone involvement only.

RESULTS

Thirty-four consecutive patients were enrolled (10 females; 24 males; median age 15.1 years). 17/34 patients (50%) had osteosarcoma, 13/34 (38%) Ewing's sarcoma, 2/34 (6%) synovial sarcoma and 2/34 (6%) embryonal liver sarcoma. Median follow-up was 39 months (range 16-84). Eight of 34 patients (24%) died, 9/34 (27%) were alive with disease, and 17/34 (50%) had no evidence of residual/recurrent disease. Fifteen of 34 (44%) and 19/34 (56%) were responders and non-responders, respectively. PET2-parameters were associated with longer TTP (p < 0.02). ΔMTV was associated with tissue response to neo-CTX (p = 0.047). None of the PET1, PET2 or ΔPET parameters were associated with OS.

CONCLUSION

[¹⁸F]FDG PET/CT performed 6 weeks after the start of neo-CTX can serve as an early interim biomarker for TTP and pathologic response but not for OS in pediatric patients with sarcoma.

The effect of Imatinib Mesylate in diffuse-type Tenosynovial Giant Cell Tumours on MR imaging and PET-CT

INTRODUCTION

Recurrence rates remain high after surgical treatment of diffuse-type Tenosynovial Giant Cell Tumour (TGCT). Imatinib Mesylate (IM) blocks Colony Stimulating Factor1 Receptor (CSF1R), the driver mechanism in TGCT. The aim of this study was to determine if IM reduces the tumour metabolic activity evaluated by PET-CT and to compare this response with the response seen on MR imaging.

MATERIALS AND METHODS

25 Consecutive patients treated with IM (off label use) for locally advanced (N = 12) or recurrent (N = 13) diffuse-type TGCT were included, 15 male and median age at diagnosis 39 (IQR 31-47) years. The knee was most frequently affected (n = 16; 64%). The effect of IM was assessed pre- and post-IM treatment by comparing MR scans and PET-CT. MR scans were assessed by Tumour Volume Score (TVS), an estimation of the tumour volume as a percentage of the total synovial cavity. PET-CT scans were evaluated based on maximum standardized uptake value (SUV-max). Partial response was defined as more than 50% tumour reduction with TVS and a decrease of at least 30% on SUV-max.

RESULTS

Median duration of IM treatment was 7.0 (IQR 4.2-11.5) months. Twenty patients (80%) discontinued IM treatment for poor response or intended surgery. Twenty patients experienced an adverse event grade 1-2, three patients grade 3 (creatinine increment, neutropenic sepsis, liver dysfunction). MR assessment of all joints showed 32% (6/19) partial response and 63% (12/19) stable disease, with a mean difference of 12% (P = 0.467; CI -22.4-46.0) TVS between pre- and post-IM and a significant mean difference of 23% (P = 0.021; CI 4.2-21.6) in all knee lesions. PET-CT, all joints, showed a significantly decreased mean difference of 5.3 (P = 0.004; CI 1.9-8.7) SUV-max between pre- and post-IM treatment (58% (11/19) partial response, 37% (7/19) stable disease). No correlation between MR imaging and PET-CT could be appreciated in 15 patients with complete radiological data.

CONCLUSION

This study confirms the moderate radiological response of IM in diffuse-type TGCT. PET-CT is a valuable additional diagnostic tool to quantify response to tyrosine kinase inhibitor treatment. Its value should be assessed further to validate its efficacy in the objective measurement of biological response in targeted systemic treatment of TGCT.

Clinical and Prognostic Role of 18F-FDG PET/CT in Pediatric Ewing Sarcoma

Ewing sarcoma (ES) is one of the most common pediatric solid tumors with aggressive behavior and unfavorable survival. In this study, we evaluated the diagnostic accuracy of baseline and restaging fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) scans and their possible prognostic role in pediatric ES. We evaluated 17 patients who underwent a total of 27 18F-FDG-PET/CT scans (10 for staging and 17 for restaging). The PET images were analyzed visually and semiquantitatively by measuring SUVmean, SUVmax, SUVlbm, SUVbsa, MTV, and TLG. Moreover, PET/CT results were compared with other conventional imaging (CI) results. Among 10 baseline PET/CT scan results, 9 were positive and 1 not valuable by interference; baseline PET/CT and CI were concordant in 7 cases and discordant in 2, with pulmonary micrometastases not detected by PET/CT. Among 17 restaging PET/CT scan results, 9 were positive and 8 negative; CI and restaging PET/CT were concordant in 9 cases and discordant in 8. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of restaging 18F-FDG-PET/CT were 73%, 83%, 89%, 62.5%, and 76%, respectively. After a median follow-up of 20 months, relapse/progression occurred in 8 patients and death in 5. A positive 18F-FDG-PET/CT at restaging was significantly associated with shorter overall survival compared with unremarkable PET/CT at the same timepoint, but not with progression-free survival. Instead, metabolic PET/CT features were not correlated with outcome. 18F-FDG-PET/CT showed a good diagnostic performance in pediatric ES; except for pulmonary micrometastases, PET/CT was better than CI at restaging. Only restaging PET/CT result was significantly correlated with overall survival.

Effectiveness of 18F-FDG PET/CT in the diagnosis and staging of osteosarcoma: a meta-analysis of 26 studies

BACKGROUND

Multiple trials have attempted to assess the diagnostic value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in osteosarcoma with results remaining inconclusive. This study aims to investigate the effectiveness of 18F-FDG PET and PET/CT in the diagnosis, staging, recurrence and metastasis formation observations of osteosarcoma through systematic review followed by meta-analysis.

METHODS

Three electronic databases, Medline/PubMed, Embase and the Cochrane Library were utilized in this study. Eligible studies that assessed the performance of 18F-FDG PET/CT for the diagnosis, staging, restaging and recurrence monitoring of osteosarcoma were retrieved utilizing specific search criteria. After screening and diluting out the non-conforming articles, all relevant articles and their data were identified and extracted to calculate the summary metrics involving sensitivity, specificity, diagnostic odd ratio (DOR), and area under the curve (AUC) to determine the effectiveness of 18F-FDG PET in diagnosing osteosarcoma clinically.

RESULTS

Out of 1976 articles searched, twenty-six studies were identified that were viable. All data from these articles, utilized in the quantitative analyses, showed after meta-analysis that when utilizing 18F-FDG PET or PET/CT it was better with a success rate of 90-100% for detecting primary lesions and distant metastases of patients with osteosarcoma. Similar results were also obtained for detecting lung and bone metastases in a subgroup analysis.

CONCLUSIONS

As such the investigation demonstrated that 18F-FDG PET and PET/CT are very accurate for the diagnosis, staging and recurrence monitoring of osteosarcoma. 18F-FDG-avid lesions should be further examined in osteosarcoma, especially for suspicious lung lesions.

18F-FDG PET-CT in paediatric oncology: established and emerging applications

Accurate staging and response assessment is vital in the management of childhood malignancies. Fluorine-18 fluorodeoxyglucose positron emission tomography/CT (FDG PET-CT) provides complimentary anatomical and functional information. Oncological applications of FDG PET-CT are not as well-established within the paediatric population compared to adults. This article will comprehensively review established oncological PET-CT applications in paediatric oncology and provide an overview of emerging and future developments in this domain.

Usefulness of Quantitative Bone Single Photon Emission Computed Tomography/Computed Tomography for Evaluating Response to Neoadjuvant Chemotherapy in a Patient with Periosteal Osteosarcoma

We report here a case of periosteal sarcoma in a 10-year-old female, along with quantitative values obtained with bone single photon emission computed tomography/computed tomography (SPECT/CT), which were useful to evaluate treatment response to preoperative chemotherapy. Pretreatment radiograph images of the lower leg showed cortical thickening eroded by a broad-based soft-tissue mass without the involvement of the underlying cortex, while computed tomography (CT) revealed a small juxtacortical mass with thick calcification and periosteal reaction. In magnetic resonance imaging (MRI), the mass showed hypointensity in the inner part and isointensity in the outer part in T1-weighted images, while the inner part showed hypointensity and the outer part hyperintensity in T2-weighted images. Bone SPECT/CT results indicated the focal and intense uptake of the mass. Following neoadjuvant chemotherapy (NAC), radiograph and MRI results revealed a slight increase in size, with growing calcification. Although visual inspection of the bone SPECT/CT findings showed nearly the same amount of focal uptake, quantitative parameters determined with those findings were decreased, with maximum standardized uptake value (SUV), peak SUV, mean SUV, metabolic bone volume (MBV), and total bone uptake (TBU) reduced by -20.7%, -22.0%, -12.6%, -33.5%, and -41.9%, respectively. The excision biopsy at the surgery showed a pathological grade 1 (non-complete response) after NAC, including a more than 20% of cell necrosis part. The quantitative bone SPECT/CT was considered to reflect treatment response in this case.

Future Perspective of the Application of Positron Emission Tomography-Computed Tomography-MR Imaging in Musculoskeletal Disorders

Fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) is the imaging method of choice in sarcoma patients. PET may help in diagnosis, grading, staging, biopsy guidance, monitoring response to therapy, restaging for recurrence, and prognosis. 18F-FDG-PET/MRI combines the higher tissue contrast of MRI in the study of soft-tissue lesions and the peculiarities of PET imaging that allow the characterization of tissues. The use of 18F-FDG-PET/MRI in these patients has reduces the radiation dose, which is of great importance, particularly in children. Data support the routine use of 18F-FDG-PET either using CT or MRI in patients with sarcoma.

[Postoperative and posttherapeutic changes after primary bone tumors : What's important for radiologists?]

Posttreatment imaging of primary bone tumours represents a diagnostic challenge for radiologists. Depending on the primary bone tumour common radiological procedures, such as radiography, computed tomography (CT), and magnetic resonance imaging (MRI), are employed. Radiography and CT are particularly useful in benign bone tumours and in matrix-forming bone tumours. MRI comes into consideration with malignant tumour recurrence and tumoral soft tissue infiltration. Bone scintigraphy is of superior importance if a primarily multifocal manifestation of bone tumour or metastasizing tumour disease is suspected. Molecular imaging (FDG-PET and hybrid imaging, using CT) are gaining increasing importance in light of monitoring neoadjuvant chemotherapy and detecting recurrent tumour appearance. The current literature shows sensitivity and specificity values for recurrent detection of up to 92% and 93%. Diagnostic accuracy is as high as 95%, thus, exceeding accuracy values for CT (67%) and MRI (86%) by far. Likewise, this is also applicable for the assessment of the neoadjuvant chemotherapy. Moreover, PET-based modalities are able to establish prognostic statements using SUV-threshold values at baseline (especially for Ewing sarcomas). Advanced imaging techniques have made a great diagnostic step forward and have proven to be relevant and reproducible with respect to both relapse detection and treatment assessment. Furthermore, it is not clear whether a higher detection rate of early tumour recurrence will inevitably lead to better outcome and survival.

Prognostic value of FDG-PET indices for the assessment of histological response to neoadjuvant chemotherapy and outcome in pediatric patients with Ewing sarcoma and osteosarcoma

Purpose

The objective of this retrospective work was to evaluate the prognostic value on histological response and survival of quantitative indices derived from FDG-PET performed before and after chemotherapy (CHT), in a homogeneous pediatric Ewing sarcoma (EWS) and Osteosarcoma (OST) population.

Methods

Thirty-one patients with EWS and 31 with OST were included. All patients were treated with neoadjuvant CHT, and underwent surgery for local control. All patients had FDG-PET at diagnosis and after CHT, prior to surgery. Several parameters were evaluated: SUVmax, SUVpeak, SUVmean, metabolic tumor volume, total lesion glycolysis, 7 textural features and 3 shape features (SF). The segmentation was performed using an adaptive approach. Results were compared to histopathological regression of the resected tumor and to clinical follow-up for survival evaluation.

Results

For EWS, univariate analysis did not highlight any prognostic value on histological response, or survival regardless of all the considered metrics. For OST, only one of the SF, namely elongation, was significantly associated with PFS and OS on both univariate and multivariate analysis (PFS: p = 0.019, HR = 5.583; OS: p = 0.0062, HR = 7.113).

Conclusion

Only elongation determined on initial FDG-PET has a potential interest as a prognostic factor of PFS and OS in pediatric OST patients. Unlike recent studies of the literature realized in adult population, all the metrics reveal limited additional prognostic value in pediatric EWS patients. This seems to reinforce the question of whether children experience different subtypes of the same pathologies than older patients, with different outcomes.

18F-FDG PET/CT as an Indicator of Survival in Ewing Sarcoma of Bone

Objective: The existing literature of 18 F-FDG PET/CT in Ewing sarcoma investigates mixed populations of patients with both soft tissue and bone primary tumors. The aim of our study was to evaluate whether the maximum standardized uptake value (SUVmax) obtained with 18F-FDG PET/CT before and after induction chemotherapy can be used as an indicator of survival in patients with Ewing sarcoma originating exclusively in the skeleton.

Materials and Methods: A retrospective database search from 2004-2011 identified 28 patients who underwent 18 F-FDG PET/CT before (SUV1, n= 28) and after (SUV2, n=23) induction chemotherapy. Mean follow up was 3.3 years and median follow up for survivors was 6.3 years (range: 2.6-9.8 years). Multivariate and univariate Cox proportional hazard model was used to assess for correlation of SUV1, SUV2, and the change in SUVmax with overall survival (OS) and progression-free survival (PFS).

Results: Mean SUVmax was 10.74 before (SUV1) and after 4.11 (SUV2) induction chemotherapy. High SUV1 (HR = 1.05, 95% CI: 1.0-1.1, P = 0.01) and SUV2 (HR =1.2, 95% CI: 1.0-1.4, P = 0.01) were associated with worse OS. A cut off point of 11.6 was identified for SUV1. SUV1 higher than 11.6 had significantly worse OS (HR = 5.71, 95% CI: 1.85 - 17.61, P = 0.003) and PFS (HR = 3.16, 95% CI: 1.13 - 8.79, P = 0.03, P < 0.05 is significant).

Conclusion: 18F-FDG PET/CT can be used as a prognostic indicator for survival in primary Ewing sarcoma of bone.

[Effectiveness of unicompartment allografts replacement for bone tumor around the knee]

Objective

To analyze the effectiveness of unicompartment allografts replacement for reconstructing bone defect after bone tumor resection around knee.

Methods

Between January 2007 and January 2014, a total of 9 patients received unicompartment allografts replacement to treat bone tumor around the knee, including 6 males and 3 females, with an average age of 25.8 years (range, 17-38 years). There were 7 patients with bone giant cell tumor (postoperative recurrence of bone giant cell tumor in 1 case) and 2 patients with chondromyxoid fibroma. The tumors were located at the distal femur in 7 cases and proximal tibia in 2 cases, and the tumors were almost at the lateral limbs. The symptom duration was 2-5 months (mean, 3.2 months). The size of lesion ranged from 6 cm×2 cm to 9 cm×4 cm by X-ray film and MRI; and the metastasis was excluded by CT. The length of the allograft was 8.0-9.2 cm (mean, 8.6 cm).

Results

The intraoperative blood loss volume was 400-550 mL (mean, 480 mL); and 0-3 U of erythrocyte was transfused after operation. The continuous exudate of incision occurred in 1 patient, and cured after 3 months; the other incisions healed primarily at 2 weeks after operation. All patients were followed up 3-10 years (mean, 6 years). No operation area infection, allograft bone poor healing or rupture was found. At 1 year after operation, the knee range of motion was 90-110° (mean, 100°); the Musculoskeletal Tumor Society score was 24-29 (mean, 26). Low density area (osteolysis) was found in 6 allografts; no articular surface collapse, hairline fracture, or fracture was found in patients; callus formation was observed in the contact surface between the allograft and the host bone, and the cortical bone showed good continuity.

Conclusion

Unicompartment allografts replacement can provide good support and function in terms of bone tumor resection, and achieve good effectiveness by biological reconstruction.

The role of 18F-FDG PET/CT in the detection of osteosarcoma recurrence

AIM

The aim of this study was to investigate the diagnostic accuracy of ¹⁸F-FDG-PET/CT in osteosarcoma patients suspicious for disease recurrence after adequate surgical therapy.

METHODS

Inclusion criteria were: a) adequate surgical treatment for proven osteosarcoma and documented complete remission after therapy; b) ¹⁸F-FDG-PET/CT performed during follow-up for clinical/diagnostic suspicion of relapse; c) new surgical treatment with excision of the suspected lesions; d) histological validation of ¹⁸F-FDG-PET/CT findings. Thirty-seven patients matching all inclusion criteria were retrospectively enrolled (20 men and 17 female). Primary surgical treatment consists of resection (31 cases) or amputation (six cases). ¹⁸F-FDG-PET/CT performance was assessed with a per-patient and per-site evaluation of sensitivity, specificity, accuracy, positive predicting value (PPV), and negative predicting value (NPV). The sites of relapse were classified as local, lung, lymphnodes (LNs), and distant (other skeletal segments and/or distant soft tissue). The disease-free survival (DFS) and the overall survival (OS) after 18F-FDG PET/CT were evaluated.

RESULTS

¹⁸F-FDG-PET/CT was positive in 89.2% (33/37) of patients. Local uptake only was observed in 35.1% patients (13/37); lung uptake only in 18.9% (7/37); distant uptake only in 2.7% (1/37) case; multiple sites of uptake in 32.4% (12/37). Histology resulted positive in 92% (34/37) of patients. A total of 51 pathologic lesions were evaluated (22 local relapse, 11 lung metastasis, 10 metastatic LNs, eight distant metastatic lesions). On a per-patient analysis ¹⁸F-FDG-PET/CT showed a sensitivity, specificity, accuracy, PPV, and NPV of 91%, 75%, 89%, 97%, 50%. On a per-site analysis the performance for local relapse was 96%, 100%, 97%, 100%, 93%, while for lung relapse detection was 80%, 100%, 92%, 100%, 88%. The mean follow-up after ¹⁸F-FDG-PET/CT was 21.5 months. At the last follow-up, 19% (7/37) of patients were death with disease, 38% (14/37) were alive with disease, and 43% (16/37) had no evidence of disease. Overall survival was 90% and 75% at 24 and 60 months, respectively.

CONCLUSION

¹⁸F-FDG-PET/CT showed valuable results for detecting recurrence(s) in osteosarcoma patients with suspicious of relapse after treatment, particularly in the detection of local relapse and lung metastasis.