Regional nodal involvement and patterns of spread along in-transit pathways in children with rhabdomyosarcoma of the extremity: a report from the Children's Oncology Group

PET/CT and PET/MR in Soft Tissue Sarcoma: An Update

Soft tissue sarcomas account for 6%-8% of pediatric cancers. The rhabdomyosarcoma family is the most frequent soft tissue sarcoma in this age group accounting for 3% of pediatric cancers. Rhabdomyosarcomas are high-grade tumors with a high propensity to metastasize. The risk-adapted, multimodal therapeutic approach for rhabdomyosarcomas incorporates a combination of surgery, radiotherapy, and multi-agent cytotoxic chemotherapy. Soft tissue sarcomas other than rhabdomyosarcoma account for 3%-4% of pediatric cancers. The nonrhabdomyosarcoma soft tissue sarcomas include both low-grade and high-grade tumors. While surgery is the mainstay of therapy in most non-rhabdomyosarcoma soft tissue sarcomas, many cases require a multimodal therapeutic approach including radiotherapy and chemotherapy. In North America, most pediatric patients with soft tissue sarcomas are treated in Children's Oncology Group clinical trials. In this article, we will primarily focus on the staging, risk stratification, imaging recommendations, and interpretations in accordance with the Children's Oncology Group trials. We will review the results and recommendations of International Soft Tissue Sarcoma Database Consortium and European trials in relevant sections where they provide complementary guidelines.

INternational Soft Tissue saRcoma ConsorTium (INSTRuCT) consensus statement: Imaging recommendations for the management of rhabdomyosarcoma

Rhabdomyosarcoma is the most common soft-tissue neoplasm in the pediatric population. The survival of children with rhabdomyosarcoma has only marginally improved over the past 25 years and remains poor for those with metastatic disease. A significant challenge to advances in treatment of rhabdomyosarcoma is the relative rarity of this disease, necessitating years to complete clinical trials. Progress can be accelerated by international cooperation and sharing national experiences. This necessitates agreement on a common language to describe patient cohorts and consensus standards to guide diagnosis, treatment, and response assessment. These goals formed the premise for creating the INternational Soft Tissue saRcoma ConsorTium (INSTRuCT) in 2017. Multidisciplinary members of this consortium have since developed international consensus statements on the diagnosis, treatment, and management of pediatric soft-tissue sarcomas. Herein, members of the INSTRuCT Diagnostic Imaging Working Group present international consensus recommendations for imaging of patients with rhabdomyosarcoma at diagnosis, at staging, and during and after completion of therapy. The intent is to promote a standardized imaging approach to pediatric patients with this malignancy to create more-reliable comparisons of results of clinical trials internationally, thereby accelerating progress in managing rhabdomyosarcoma and improving survival.

Imaging of pediatric extremity soft tissue tumors: A COG Diagnostic Imaging Committee/SPR Oncology Committee White Paper

Pediatric soft tissue tumors of the extremity include rhabdomyosarcoma and nonrhabdomyosarcoma neoplasms. This manuscript provides consensus-based imaging recommendations for imaging evaluation at diagnosis, during treatment, and following completion of therapy for patients with a soft tissue tumor of the extremity.

Surgical management of extremity rhabdomyosarcoma: A consensus opinion from the Children's Oncology Group, the European Pediatric Soft-Tissue Sarcoma Study Group, and the Cooperative Weichteilsarkom Studiengruppe

The treatment of extremity rhabdomyosarcoma remains a challenge due to several adverse prognostic factors frequently associated with this tumor site. The International Soft-Tissue Sarcoma Database Consortium (INSTRuCT) is a collaboration of the Children's Oncology Group Soft-Tissue Sarcoma Committee, the European Pediatric Soft-Tissue Sarcoma Study Group, and the Cooperative Weichteilsarkom Studiengruppe. The INSTRuCT surgical committee developed an internationally applicable consensus opinion document for the surgical treatment of extremity rhabdomyosarcoma. This document addresses surgical management, including biopsy, nodal staging, timing of therapy, resection and reexcision, reconstruction, and surgical approach at relapse.

Clinical group and modified TNM stage for rhabdomyosarcoma: A review from the Children's Oncology Group

The Children's Oncology Group (COG) uses Clinical Group (CG) and modified Tumor Node Metastasis (TNM) stage to classify rhabdomyosarcoma (RMS). CG is based on surgicopathologic findings and is determined after the completion of initial surgical procedure(s) but prior to chemotherapy and/or radiation therapy. The modified TNM stage is based on clinical and radiographic findings and is assigned prior to any treatment. These systems have evolved over several decades. We review the history, evolution, and rationale behind the current CG and modified TNM classification systems used by COG for RMS. Data from the seven most recently completed and reported frontline COG trials (D9602, D9802, D9803, ARST0331, ARST0431, ARST0531, ARST08P1) were analyzed, and confirm that CG and modified TNM stage remain relevant and useful for predicting prognosis in RMS. We propose updates based on recent data and discuss factors warranting future study to further optimize these classification systems.

Surgical treatment for extremity rhabdomyosarcoma: longitudinal national questionnaire survey in Japan

BACKGROUND

Extremity rhabdomyosarcoma differs from other soft tissue sarcomas, being highly sensitive to chemotherapy and radiotherapy and having a high rate of metastasis to lymph nodes. Therefore, the treatment modality differs from that of other soft tissue sarcomas. The purpose of this study was to conduct a longitudinal questionnaire survey of orthopedic oncologists in charge of surgical treatment for extremity rhabdomyosarcoma in Japan to determine whether the treatment modality chosen here is in line with the international and national treatment ones.

METHODS

Questionnaire surveys were conducted in 2012 and 2019 to orthopedic oncologists of Japanese Orthopaedic Association and Japanese Musculoskeletal Oncology Group.

RESULTS

Responses were obtained from 80 facilities and 76 facilities, respectively. Fewer than 50% of the facilities treated one or more patients a year in both years. Many facilities first performed diagnostic biopsy, but most did not perform pretreatment re-excision. The number of facilities that provided radiotherapy in addition to surgery increased significantly from 2012 to 2019 (P = 0.028), but it was still 21% in 2019. The number of facilities performing excision and lymph node dissection was 19% in both 2012 and 2019, which was a very low result without improvement. The departments responsible for follow-up have been changed to pediatrics and orthopedic oncology in tandem (P = 0.0004).

CONCLUSIONS

Radiotherapy and pathological evaluation of lymph nodes are important for improving the prognosis of patients with extremity rhabdomyosarcoma. It is necessary to continue and develop more efficient educational activities on the appropriate medical treatment modalities for extremity RMS.

Value of the Sentinel Node Procedure in Pediatric Extremity Rhabdomyosarcoma: A Systematic Review and Retrospective Cohort Study

Background

Our aim is to show whether the sentinel node procedure (SNP) is recommendable for pediatric patients with extremity rhabdomyosarcoma (RMS). Lymph node metastases are an important prognostic factor in pediatric patients with extremity RMS. Accurate nodal staging is necessary to treat the patient accordingly. An alternative to the current recommended lymph node sampling is the sentinel node procedure (SNP).

Methods

A systematic review was performed summarizing all published cases of SNP in addition to 13 cases from our hospital and 8 cases from two other hospitals that have not been published before.

Results

For all patients (n = 55), at least one SLN was identified, but the SNP technique used was not uniform. The SNP changed the nodal classification of eight patients (17.0%) and had a false-negative rate of 10.5%.

Conclusions

The SNP is recommendable for pediatric patients with extremity RMS. It can change lymph node status and can be used to sample patients in a more targeted way than nodal sampling alone. Therefore, we recommend use of the SNP in addition to clinical and radiological nodal assessment for pediatric patients with extremity RMS.

Pattern of relapse in pediatric localized extremity rhabdomyosarcomas correlated with locoregional therapies administered

BACKGROUND

Treatment of extremity rhabdomyosarcomas (RMS) includes chemotherapy, surgery, and radiotherapy. Lymph node irradiation is recommended in the presence of regional node involvement at diagnosis. The aim of this study was to analyze the correlation between the pattern of relapse of non-metastatic extremity RMS and the initial therapies delivered.

METHODS

All patients with localized extremity RMS prospectively treated in France in the MMT-95 and RMS-05 protocols were selected. Extent of disease and pattern of relapse were evaluated by clinical examination and imaging.

RESULTS

We identified 59 patients with clinical characteristics corresponding to unfavorable prognostic factors. Twenty patients (34%) were considered to have lymph node involvement at diagnosis. Regional node biopsy was performed in 32 patients (54%) and modified the lymph node stage in 8 of the 59 patients (14%). Seventy-three percent of patients received radiotherapy. Fifty-two patients achieved first remission. Overall, 26 patients underwent complete tumor resection, 17 had R1 margins, and 5 were not operated due to early tumor progression. With a median follow-up of 82 months (range: 5-287), 18 relapses had occurred, at least locoregional in 12 cases. The 5‑year local and nodal control rates were 73% (63-86%) and 86% (77-95%), respectively. Five-year progression-free and overall survival were 57% (95%CI [45-72%]) and 70% (95%CI [58-84%]), respectively.

CONCLUSION

The main sites of extremity RMS relapse are locoregional. Nodal failures in non-irradiated fields are not uncommon. We recommend systematic biopsy of in-transit nodes, especially in alveolar RMS and/or RMS with regional positive nodes at diagnosis to ensure their negativity.

Imaging of Soft Tissue Tumors

Differentiation of malignant from benign soft tissue tumors is challenging with imaging alone, including that by magnetic resonance imaging and computed tomography. However, the accuracy of this differentiation has increased owing to the development of novel imaging technology. Detailed patient history and physical examination remain essential for differentiation between benign and malignant soft tissue tumors. Moreover, measurement only of tumor size based on Response Evaluation Criteria In Solid Tumors criteria is insufficient for the evaluation of response to chemotherapy or radiotherapy. Change in metabolic activity measured by ¹⁸F-fluorodeoxyglucose positron emission tomography or dynamic contrast enhanced-derived quantitative endpoints can more accurately evaluate treatment response compared to change in tumor size. Magnetic resonance imaging can accurately evaluate essential factors in surgical planning such as vascular or bone invasion and "tail sign". Thus, imaging plays a critical role in the diagnosis and treatment of soft tissue tumors.

Lymphadenopathy in children: A streamlined approach for the surgeon - A report from the APSA Cancer Committee

BACKGROUND/PURPOSE

Lymphadenopathy is a common complaint in children. Pediatric surgeons are often called upon to evaluate, treat, and/or biopsy enlarged lymph nodes. With many nonsurgical causes in the differential diagnosis, the surgeon plays the important role of providing reassurance and timely diagnosis while minimizing the pain and morbidity associated with surgical interventions in children. The purpose of this summary paper is to provide a management guide for surgeons working up children with lymphadenopathy.

MATERIALS/METHODS

The English language literature was searched for "lymphadenopathy in children". All manuscript types were considered for review, regardless of medical specialty, with emphasis placed on published guidelines, algorithms, and reviews. After thorough review of these manuscripts and cross-referencing of their bibliographies, the attached algorithm was developed, with emphasis on the role and timing of surgical intervention.

RESULTS

The APSA Cancer Committee developed the attached algorithm to fill a gap in the surgical literature. It outlines lymphadenopathy workup and treatment with emphasis on the role and timing of surgical intervention.

CONCLUSION

This review defines and summarizes the common etiologies and presentations of lymphadenopathy in children, and offers a straightforward algorithm for evaluation of and treatment with an emphasis on malignancy risk and surgical management.

TYPE OF STUDY

Summary paper.

LEVEL OF EVIDENCE

Level V.

European guideline for imaging in paediatric and adolescent rhabdomyosarcoma - joint statement by the European Paediatric Soft Tissue Sarcoma Study Group, the Cooperative Weichteilsarkom Studiengruppe and the Oncology Task Force of the European Society of Paediatric Radiology

Appropriate imaging is essential in the treatment of children and adolescents with rhabdomyosarcoma. For adequate stratification and optimal individualised local treatment utilising surgery and radiotherapy, high-quality imaging is crucial. The paediatric radiologist, therefore, is an essential member of the multi-disciplinary team providing clinical care and research. This manuscript presents the European rhabdomyosarcoma imaging guideline, based on the recently developed guideline of the European Paediatric Soft Tissue Sarcoma Study Group (EpSSG) Imaging Committee. This guideline was developed in collaboration between the EpSSG Imaging Committee, the Cooperative Weichteilsarkom Studiengruppe (CWS) Imaging Group, and the Oncology Task Force of the European Society of Paediatric Radiology (ESPR). MRI is recommended, at diagnosis and follow-up, for the evaluation of the primary tumour and its relationship to surrounding tissues, including assessment of neurovascular structures and loco-regional lymphadenopathy. Chest CT along with [F-18]2-fluoro-2-deoxyglucose (FDG) positron emission tomography (PET)/CT or PET/MRI are recommended for the detection and evaluation of loco-regional and distant metastatic disease. Guidance on the estimation of treatment response, optimal long-term follow-up, technical imaging settings and standardised reporting are described. This European imaging guideline outlines the recommendations for imaging in children and adolescents with rhabdomyosarcoma, with the aim to harmonise imaging and to advance patient care.

Update on pediatric rhabdomyosarcoma: A report from the APSA Cancer Committee

BACKGROUND/PURPOSE

Rhabdomyosarcoma is the most common soft tissue sarcoma in children and young adults and requires multimodality treatment. The purpose of this review is to present an update on risk stratification as well as surgical and medical management strategies in pediatric rhabdomyosarcoma.

METHODS

A comprehensive review of the current literature on pediatric rhabdomyosarcoma, including the most recent Children's Oncology Group studies and several international collaboratives, was performed by the authors and key findings were summarized in the manuscript.

RESULTS

FOXO1 fusion status is a stronger prognostic factor than histology and is now used for risk stratification in treatment protocols. For assessment of regional nodal involvement, FDG-PET-CT shows poor sensitivity and specificity to detect histologically confirmed nodal metastasis. Thus, surgical assessment of regional lymph nodes is required for rhabdomyosarcoma of the extremities or trunk as well as paratesticular rhabdomyosarcoma in patients ≥10 years of age, although adherence to surgical guidelines remains poor. Hemiscrotectomy performed for scrotal violation in paratesticular rhabdomyosarcoma has not shown an improvement in event free survival and is not recommended.

CONCLUSIONS

Surgical and medical treatment strategies for rhabdomyosarcoma in children continue to evolve. This review provides current evidence-based treatment standards with an emphasis on surgical care.

TYPE OF STUDY

Review.

LEVEL OF EVIDENCE

Level IV.

Survival stratification in childhood rhabdomyosarcoma of the extremities: a derivation and validation study

The objective of this study was to estimate overall survival in children with extremity rhabdomyosarcoma (RMS). In addition, we attempted to construct a nomogram to predict the prognosis in such patients using a population-based cohort. The national Surveillance, Epidemiology, and End Results (SEER) registry was used to identify a cohort of childhood RMS patients. A total of 197 patients with RMS were ultimately included. Multivariable analysis identified age group, N classification, M classification, and treatment combinations as independent predictive factors for patient overall survival. Candidate variables such as age group, N classification, M classification, and treatment combinations were used to fit the model. For overall survival, the bootstrap-adjusted c-index was 0.76 (95% CI, 0.73–0.80) for the nomogram. Furthermore, we performed recursive partitioning analysis for risk stratification according to overall survival, and 3 prognostic subgroups were generated (low, intermediate and high risk). Finally, we evaluated multimodal treatment based on the risk stratification according to the nomogram and IRSG prognostic stratification model. With regard to the entire cohort, overall survival in patients who received surgery and radiation was superior to that in patients who received surgery or radiation (p = 0.001). Regarding RPA and IRSG prognostic stratification, we found that the differences remained significant (p < 0.05) in patients with low-intermediate risk. However, the difference disappeared in patients with high risk (p > 0.05). We performed a population-based analysis of data from the SEER registry in an effort to identify prognostic factors and develop a nomogram in children with extremity RMS. The nomogram appears to be suitable for the survival stratification of children with RMS and will help clinicians identify patients who may be at a reduced probability of survival and assist them in making treatment and surveillance decisions. More studies concerning overall survival in children with RMS are needed to confirm and update our findings.

Lymph Node Sampling and Survival in Child and Adolescent Extremity Soft-Tissue Sarcoma

BACKGROUND

The significance of lymph node sampling (LNS) on disease-specific survival (DSS) of extremity soft tissue sarcomas (STS) is unknown. We investigated the effect of LNS on DSS in child and adolescent extremity STS.

MATERIALS AND METHODS

The Surveillance, Epidemiology, and End Results registry was queried for patients aged <20 y with extremity STS who underwent surgery. Patient demographics were collected and analyzed.

RESULTS

A total of 1550 patients were included, with findings of 10-y DSS of 74% for all extremity STS and 49% for rhabdoymyosarcoma (RMS) (P < 0.005). LNS was associated with worse DSS in patients with extremity nonrhabdomyosacrcoma soft tissue sarcomas (79% versus 84%, P = 0.036). Conversely, LNS was associated with an improved DSS in patients with extremity RMS (64% versus 49%, P = 0.005).

CONCLUSIONS

LNS is positively associated with an improved DSS in child and adolescent extremity RMS. Multivariate analysis found no correlation between DSS and LNS in child and adolescent extremity nonrhabdomyosarcoma soft tissue sarcomas.

Rhabdomyosarcoma and Extraosseous Ewing Sarcoma

Rhabdomyosarcoma (RMS) is a malignant tumor that represents the most common form of pediatric soft tissue sarcoma. It arises from mesenchymal origin and forms part of the group of small round blue cell tumors of childhood. It has a constant annual incidence of 4.5 cases per 1,000,000 children. The known histological diagnosis of the two major subtypes (embryonal and alveolar) has been recently enhanced by tumor biological markers and molecular differentiation diagnostic tools that have improved not only the updated classification based on risk stratification, but also the treatment approach based on the clinical group. Ewing sarcoma (ES) is a round cell tumor, highly malignant and poorly differentiated that is currently the second most common malignant bone tumor in children. In rare instances, it develops from an extraskeletal origin, classified as extraosseous Ewing sarcoma (EES). We provide an updated, evidence-based and comprehensive review of the molecular diagnosis, clinical and diagnostic approach and a multidisciplinary medical and surgical management according to the latest standard of care for the treatment of pediatric RMS and EES.

The Children's Oncology Group Radiation Oncology Discipline: 15 Years of Contributions to the Treatment of Childhood Cancer

PURPOSE

Our aim was to review the advances in radiation therapy for the management of pediatric cancers made by the Children's Oncology Group (COG) radiation oncology discipline since its inception in 2000.

METHODS AND MATERIALS

The various radiation oncology disease site leaders reviewed the contributions and advances in pediatric oncology made through the work of the COG. They have presented outcomes of relevant studies and summarized current treatment policies developed by consensus from experts in the field.

RESULTS

The indications and techniques for pediatric radiation therapy have evolved considerably over the years for virtually all pediatric tumor types, resulting in improved cure rates together with the potential for decreased treatment-related morbidity and mortality.

CONCLUSIONS

The COG radiation oncology discipline has made significant contributions toward the treatment of childhood cancer. Our discipline is committed to continuing research to refine and modernize the use of radiation therapy in current and future protocols with the goal of further improving the cure rates and quality of life of children with cancer.

Fusion status in patients with lymph node-positive (N1) alveolar rhabdomyosarcoma is a powerful predictor of prognosis: Experience of the European Paediatric Soft Tissue Sarcoma Study Group (EpSSG)

BACKGROUND

Alveolar rhabdomyosarcoma (aRMS) with lymph node involvement (N1 classification) accounts for up to 10% of all cases of RMS. The prognosis is poor, and is comparable to that of distant metastatic disease. In the European Paediatric Soft Tissue Sarcoma Study Group (EpSSG) RMS2005 protocol, patients with a histologic diagnosis of aRMS/N1 received intensified chemotherapy with systematic locoregional treatment.

METHODS

Patients with aRMS/N1 were enrolled prospectively after primary surgery/biopsy and fusion status was assessed in tumor samples. All patients received 9 cycles of induction chemotherapy and 6 months of maintenance therapy. Local treatment included radiotherapy to the primary site and lymph nodes with or without secondary surgical resection.

RESULTS

A total of 103 patients were enrolled. The clinical characteristics of the patients were predominantly unfavorable: 90% had macroscopic residual disease after initial surgery/biopsy, 63% had locally invasive tumors, 77% had a tumor measuring >5 cm, and 81% had disease at unfavorable sites. Fusion genes involving forkhead box protein O1 (FOXO1) were detected in 56 of 84 patients. Events occurred in 52 patients: 43 developed disease recurrence, 7 had disease that was refractory to treatment, and 2 patients developed second neoplasms. On univariate analysis, unfavorable disease site, tumor invasiveness, Intergroup Rhabdomyosarcoma Study group III, and fusion-positive status correlated with worse prognosis. The 5-year event-free survival rate of patients with fusion-positive tumors was 43% compared with 74% in patients with fusion-negative tumors (P = .01). On multivariate analysis, fusion positivity and tumor invasiveness proved to be unfavorable prognostic markers.

CONCLUSIONS

Fusion status and tumor invasiveness appear to have a strong impact on prognosis in patients with aRMS/N1. Fusion status will be used to stratify these patients in the next EpSSG RMS study, and treatment will be intensified in patients with fusion-positive tumors. Cancer 2018. © 2018 American Cancer Society.

Quality assessment of lymph node sampling in rhabdomyosarcoma: A surveillance, epidemiology, and end results (SEER) program study

BACKGROUND

Lymph node sampling is integral in the management of extremity and paratesticular rhabdomyosarcoma (RMS). The aim of this study was to determine overall surgical compliance with treatment protocols and impact of nodal sampling outcomes in these tumors.

METHODS

A query of the surveillance, epidemiology, and end results program (SEER) database was performed from 2003 to 2008 for patients <19years of age with RMS. Data obtained included demographics, five-year survival and rate of nodal sampling. Analysis was performed utilizing chi-squared, Kaplan-Meier and hazard ratio modeling.

RESULTS

Of 537 patients with extremity RMS, nodal sampling was performed in 25.7% (n=138). This lack of nodal sampling had a negative outcome on survival (p=0.004). Sixty five patients with paratesticular RMS aged greater than 10 were identified and also displayed low rates of lymph node sampling (47.7%, n=31). For paratesticular patients, a similar increase in survival was seen in patients who underwent nodal evaluation (p=0.024).

CONCLUSION

Lymph node sampling is the standard of care in RMS. However, surgical compliance with treatment protocols is poor. Nodal evaluation correlated significantly with overall survival. These findings suggest a need for improved education among surgeons and oncologists regarding the need lymph node assessment in pediatric oncology patients. Evidence rating/classification: Prognosis study, Level III.

Rhabdomyosarcoma

A malignant tumor of striated muscle origin, rhabdomyosarcoma (RMS) is a childhood tumor that has benefited from nearly 30 years of multimodality therapy, culminating in a >70% overall 5-year survival. Prognosis for RMS is dependent on primary tumor site, age, completeness of resection, presence and number of metastatic sites, histology, and biology of the tumor cells. Multimodality treatment is based on risk stratification according to pre-treatment stage, postoperative group, histology, and site. Unique to RMS is the concept of postoperative clinical grouping that assesses the completeness of disease resection and takes into account lymph node evaluation at both the regional and metastatic basins. At all sites, if complete operative resection of disease is accomplished, including microscopic disease, survival is improved. Therefore, the surgeon plays a vital role in determining risk stratification for treatment, local control of the primary tumor and overall outcome for the patient with RMS.

Detection of lymph node metastases in pediatric and adolescent/young adult sarcoma: Sentinel lymph node biopsy versus fludeoxyglucose positron emission tomography imaging-A prospective trial

BACKGROUND

Lymph node metastases are an important cause of treatment failure for pediatric and adolescent/young adult (AYA) sarcoma patients. Nodal sampling is recommended for certain sarcoma subtypes that have a predilection for lymphatic spread. Sentinel lymph node biopsy (SLNB) may improve the diagnostic yield of nodal sampling, particularly when single-photon emission computed tomography/computed tomography (SPECT-CT) is used to facilitate anatomic localization. Functional imaging with positron emission tomography/computed tomography (PET-CT) is increasingly used for sarcoma staging and is a less invasive alternative to SLNB. To assess the utility of these 2 staging methods, this study prospectively compared SLNB plus SPECT-CT with PET-CT for the identification of nodal metastases in pediatric and AYA patients.

METHODS

Twenty-eight pediatric and AYA sarcoma patients underwent SLNB with SPECT-CT. The histological findings of the excised lymph nodes were then correlated with preoperative PET-CT imaging.

RESULTS

A median of 2.4 sentinel nodes were sampled per patient. No wound infections or chronic lymphedema occurred. SLNB identified tumors in 7 of the 28 patients (25%), including 3 patients who had normal PET-CT imaging of the nodal basin. In contrast, PET-CT demonstrated hypermetabolic regional nodes in 14 patients, and this resulted in a positive predictive value of only 29%. The sensitivity and specificity of PET-CT for detecting histologically confirmed nodal metastases were only 57% and 52%, respectively.

CONCLUSIONS

SLNB can safely guide the rational selection of nodes for biopsy in pediatric and AYA sarcoma patients and can identify therapy-changing nodal disease not appreciated with PET-CT. Cancer 2017;155-160. © 2016 American Cancer Society.

Prognostic Factors for Outcome in Localized Extremity Rhabdomyosarcoma. Pooled Analysis from Four International Cooperative Groups

BACKGROUND

Extremity rhabdomyosarcomas do not always show satisfactory outcomes. We analyzed data from 643 patients treated in 14 studies conducted by European and North American groups between 1983 and 2004 to identify factors predictive of outcome.

PROCEDURE

Clinical factors, including age; histology; site of primary (hand and foot vs. other); size; invasiveness (T stage); nodal involvement (N stage); and treatment factors, including post-surgical group; chemotherapy type and duration; radiotherapy; and treatment (before or after 1995); were evaluated for impact on overall survival (OS).

RESULTS

5-year OS were 67% (se 1.8). Multivariate analysis showed that lower OS correlated with age >3 years, T2 and N1 stage, incomplete initial surgery, treatment before 1995, and European cooperative group treatment. Patients with gross residual disease after initial incomplete resection/biopsy had similar outcomes in both continental groups. The better global survival of patients treated in American studies was accounted for by differences in outcome in the subset of those with grossly resected tumors (OS 86% [se 3] for COG patients vs. 68% [se 4] for European patients (P = 0.004)). When excluding chemotherapy duration from the model, analysis in this subset of patients showed that cooperative group (P = 0.001), site (P = 0.001), and T stage (P = 0.05) were all significant. However, after adding duration of chemotherapy (≥27 weeks) to the model, only primary site remained significant (P = 0.006).

CONCLUSION

This meta-analysis confirms the role of many established prognostic factors but identifies for the first time that chemotherapy duration may have an impact on outcome in patients with grossly resected tumors.

Recent advances in understanding and managing rhabdomyosarcoma

Rhabdomyosarcoma is the most common childhood soft tissue sarcoma and the fourth most common pediatric solid tumor. For most patients, treatment consists of a multimodality approach, including chemotherapy, surgery, and/or radiotherapy. To guide treatment, patients with rhabdomyosarcoma are risk stratified based on a number of factors. These factors include clinical group, which depends largely on the extent of resection and nodal involvement, and stage, which takes into account tumor size, invasion, nodal involvement, and disease site. Histology of the tumor and age at diagnosis are also factored into risk stratification. Recent advances in understanding the biology of the disease have allowed for the further sub-classification of rhabdomyosarcoma. In addition, elucidation of additional clinical features associated with poor prognosis has allowed for better understanding of risk and provides more clarity regarding those patients who require more intensive therapy. Many areas of active investigation are ongoing, including the following: further delineation of the biological underpinnings of the various disease subtypes with the possibility of molecularly targeted therapy; a better understanding of clinical risk factors, including the evaluation and management of potentially involved lymph nodes; determination of the appropriate role of post-treatment imaging and assessment of response to therapy; and incorporation of advanced radiotherapeutic techniques, including conformal intensity-modulated photon and proton therapy.

Children's Oncology Group's 2013 blueprint for research: Soft tissue sarcomas

In the US, approximately 850-900 children are diagnosed each year with soft tissue sarcomas (STS). Key findings from recent Children's Oncology Group (COG) clinical trials include safe reduction in therapy for low risk rhabdomyosarcoma (RMS), validation of FOXO1 fusion as a prognostic factor, a modest improvement in outcome for high-risk RMS, and a biologically designed non-cytotoxic therapy for pediatric desmoid tumor. Planned Phase 2 trials include targeted agents for VEGF/PDGF, mTOR, and IGF-1R for children with RMS and VEGF for children with non-RMS STS (NRSTS). For RMS, COG Phase 3 trials potentially will explore VEGF/mTOR inhibition or chemotherapy interval compression. For NRSTS, a COG Phase 3 trial will explore VEGF inhibition.

Radiotherapy for rhabdomyosarcoma: indications and outcome

Rhabdomyosarcoma is the most common soft tissue sarcoma of childhood. Improvements in the clinical outcomes of rhabdomyosarcoma have been secondary to the intensification and refinement of treatment investigated by the Intergroup Rhabdomyosarcoma Study Group. Advances in diagnostic imaging techniques have led to improvements in staging and contribute to precision in radiation field design. Radiation treatment has been integrated into the primary treatment of most patients with rhabdomyosarcoma. Each treatment site has special considerations with regards to prognosis, outcomes and potential morbidities that affect the choice of local therapy. Advanced radiotherapy techniques using conformal treatment with intensity-modulated radiotherapy and proton therapy are particularly advantageous for the treatment of sites close to critical structures, such as the head and neck and genitourinary system. Active investigation is underway to develop strategies to reduce the radiation dose and volume in an effort to minimise late toxicity and improve the therapeutic ratio.

18F-FDG microPET imaging detects early transient response to an IGF1R inhibitor in genetically engineered rhabdomyosarcoma models

BACKGROUND

Alveolar rhabdomyosarcoma (ARMS) and embryonal rhabdomyosarcoma (ERMS) are among the most common and most treatment resistant soft tissue sarcomas of childhood. Here, we evaluated the potential of (18)F-Fluorodeoxyglucose (FDG) as a marker of therapeutic response to picropodophyllin (PPP), an IGF1R inhibitor, in a conditional mouse model of ARMS and a conditional model of ERMS/undifferentiated pleomorphic sarcoma (UPS).

PROCEDURE

Primary tumor cell cultures from Myf6Cre,Pax3:Fkhr,p53 and Pax7CreER,Ptch1,p53 conditional models of ARMS and ERMS/UPS were found to be highly sensitive to PPP (IC(50) values 150 and 200 nM, respectively). Animals of each model were then treated with 80 mg/kg/day PPP by intraperitoneal injection for 12 days and imaged by (18)F-FDG microPET.

RESULTS

Tumor volumes on day 4 for PPP-treated ARMS and ERMS mice were lower than untreated control mouse tumor volumes, although treated tumors were larger than day 0. However, tumor FDG uptake was significantly reduced on day 4 for PPP-treated mice compared to pretreatment baseline or untreated control mice on day 4 (P < 0.05). Nevertheless, by day 12 tumor volumes and FDG uptake for treated mice had increased significantly, indicating rapidly evolving resistance to therapy.

CONCLUSIONS

(18)F-FDG PET imaging is a potential imaging biomarker of molecular susceptibility to targeted agents early in treatment for this aggressive form of sarcoma, but may find best use serially for Phase I/II studies where chemotherapy and targeted agents are combined to cytoreduce tumors and abrogate Igf1r inhibitor resistance.

Intensity modulated radiation therapy with dose painting to treat rhabdomyosarcoma

PURPOSE

To examine local control and patterns of failure in rhabdomyosarcoma patients treated with intensity modulated radiation therapy (RT) with dose painting (DP-IMRT).

PATIENTS AND METHODS

A total of 41 patients underwent DP-IMRT with chemotherapy for definitive treatment. Nineteen also underwent surgery with or without intraoperative RT. Fifty-six percent had alveolar histologic features. The median interval from beginning chemotherapy to RT was 17 weeks (range, 4-25). Very young children who underwent second-look procedures with or without intraoperative RT received reduced doses of 24-36 Gy in 1.4-1.8-Gy fractions. Young adults received 50.4 Gy to the primary tumor and lower doses of 36 Gy in 1.8-Gy fractions to at-risk lymph node chains.

RESULTS

With 22 months of median follow-up, the actuarial local control rate was 90%. Patients aged ≤7 years who received reduced overall and fractional doses had 100% local control, and young adults had 79% (P=.07) local control. Three local failures were identified in young adults whose primary target volumes had received 50.4 Gy in 1.8-Gy fractions.

CONCLUSIONS

DP-IMRT with lower fractional and cumulative doses is feasible for very young children after second-look procedures with or without intraoperative RT. DP-IMRT is also feasible in adolescents and young adults with aggressive disease who would benefit from prophylactic RT to high-risk lymph node chains, although dose escalation might be warranted for improved local control. With limited follow-up, it appears that DP-IMRT produces local control rates comparable to those of sequential IMRT in patients with rhabdomyosarcoma.