Local Control For High-Grade Nonrhabdomyosarcoma Soft Tissue Sarcoma Assigned to Radiation Therapy on ARST0332: A Report From the Childrens Oncology Group

Contemporary surgical management of pediatric non-rhabdomyosarcoma soft tissue sarcoma

Non-rhabdomyosarcoma soft tissue sarcoma (STS) comprises most STS in pediatric patients. It is a diverse set of over 30 histologic subtypes. Treatment is based on risk group determined by tumor size, grade, and the presence of metastases. Surgical resection is a cornerstone of therapy, as tumors are often resistant to chemotherapy or radiation. While patients with isolated tumors less than 5 cm may undergo upfront resection, strong consideration should be given to neoadjuvant chemoradiotherapy to ensure negative margins at surgical resection and optimal outcomes. Sentinel lymph node biopsy is strongly recommended for clear cell and epithelioid sarcomas. The most common metastatic site is the lung, and metastases should be resected at the end of therapy, when feasible. Unfortunately, many high-risk patients progress on therapy, and alternative strategies including earlier metastatic control require investigation.

Proton Therapy in Non-Rhabdomyosarcoma Soft Tissue Sarcomas of Children and Adolescents

This paper provides insights into the use of Proton Beam Therapy (PBT) in pediatric patients with non-rhabdomyosarcoma soft tissue sarcomas (NRSTS). NRSTS are a heterogeneous group of rare and aggressive mesenchymal extraskeletal tumors, presenting complex and challenging clinical management scenarios. The overall survival rate for patients with NRSTS is around 70%, but the outcome is strictly related to the presence of various variables, such as the histological subtype, grade of malignancy and tumor stage at diagnosis. Multimodal therapy is typically considered the preferred treatment for high-grade NRSTS. Radiotherapy plays a key role in the treatment of children and adolescents with NRSTS. However, the potential for radiation-induced side effects partially limits its use. Therefore, PBT represents a very suitable therapeutic option for these patients. The unique depth-dose characteristics of protons can be leveraged to minimize doses to healthy tissue significantly, potentially allowing for increased tumor doses and enhanced preservation of surrounding tissues. These benefits suggest that PBT may improve local control while reducing toxicity and improving quality of life. While clear evidence of therapeutic superiority of PBT over other modern photon techniques in NRSTS is still lacking-partly due to the limited data available-PBT can be an excellent treatment option for young patients with these tumors. A dedicated international comprehensive collaborative approach is essential to better define its role within the multidisciplinary management of NRSTS. Shared guidelines for PBT indications-based on the patient's age, estimated outcome, and tumor location-and centralization in high-level referral centers are needed to optimize the use of resources, since access to PBT remains a challenge due to the limited number of available proton therapy facilities.

Children's Oncology Group's 2023 blueprint for research: Soft tissue sarcomas

In the United States, approximately 850-900 children and adolescents each year are diagnosed with soft tissue sarcomas (STS). STS are divided into rhabdomyosarcoma (RMS) and non-rhabdomyosarcoma STS (NRSTS). RMS and NRSTS are risk stratified into low-, intermediate-, and high-risk categories, with 5-year survival rates of approximately 90%, 50%-70%, and 20%, respectively. Recent key achievements from the Children's Oncology Group (COG) STS Committee include the identification of new molecular prognostic factors for RMS, development and validation of a novel risk stratification system for NRSTS, successful completion of a collaborative NRSTS clinical trial with adult oncology consortia, and collaborative development of the INternational Soft Tissue SaRcoma ConsorTium (INSTRuCT). Current COG trials for RMS are prospectively evaluating a new risk stratification system that incorporates molecular findings, de-intensification of therapy for a very low-risk subgroup, and augmented therapy approaches for intermediate- and high-risk RMS. Trials for NRSTS exploring novel targets and local control modalities are in development.

Neoadjuvant pazopanib in nonrhabdomyosarcoma soft tissue sarcomas (ARST1321): A report of major wound complications from the Children's Oncology Group and NRG Oncology

BACKGROUND AND OBJECTIVES

The impact upon wound healing of targeted molecular therapies, when incorporated into neoadjuvant therapy of soft tissue sarcoma, is largely unknown. Here, we describe wound complications following addition of pazopanib, a tyrosine kinase inhibitor (TKI), to neoadjuvant radiotherapy (RT) +/- chemotherapy for soft tissue sarcoma.

METHODS

Wound complications were evaluated on dose-finding and randomized arms of ARST1321, a phase II/III study incorporating neoadjuvant RT, +/- pazopanib, +/- ifosfamide/doxorubicin (ID) for sarcoma therapy.

RESULTS

Of 85 evaluable patients, 35 (41%) experienced postoperative wound complications. Most (57%) were grade III. Randomization to pazopanib + RT + ID carried a 50% wound complication rate (17/34, with 47% grade III), compared to 22% (5/23) with ID + RT alone. In nonchemotherapy study arms, pazopanib + RT resulted in a 59% wound complication rate versus 25% for those receiving RT alone. Grade III wound complications occurred among 26% (15/58) of all patients receiving pazopanib. Wound complications occurred a median of 35 days postoperatively. Some occurred following diagnostic biopsies and at remote surgical sites.

CONCLUSION

The addition of pazopanib to neoadjuvant chemotherapy and RT resulted in a higher wound complication rate following therapy of soft tissue sarcoma. The rate of grade III complications remained comparable to that reported in contemporary literature.

The significance of margins in pediatric Non-Rhabdomyosarcoma soft tissue sarcomas: Consensus on surgical margin definition harmonization from the INternational Soft Tissue SaRcoma ConsorTium (INSTRuCT)

BACKGROUND

Margin status following surgery in children, adolescents, and young adults with soft tissue sarcomas is controversial and has been defined differently by various specialties, with definitions changing over time and by cooperative group. The International Soft Tissue Sarcoma Consortium (INSTRuCT) is a collaboration of the Children's Oncology Group (COG) Soft Tissue Sarcoma Committee, European pediatric Soft Tissue sarcoma Study Group (EpSSG), and the European Cooperative Weichteilsarkom Studiengruppe (CWS) devoted to improving patient outcomes by pooling and mining cooperative group clinical trial data.

METHODS

The INSTRuCT non-rhabdomyosarcoma soft tissue sarcoma (NRSTS) working group aimed to develop international harmonized recommendations regarding surgical margin assessment and definitions in children and adolescents with soft tissue tumors.

RESULTS AND CONCLUSION

This review addresses accepted principles and areas of controversy, including the perspectives of surgeons, pathologists, radiation oncologists, and pediatric oncologists, to develop a framework for building common guidelines for future research.

International Society of Paediatric Surgical Oncology (IPSO) Surgical Practice Guidelines

Most children with tumors will require one or more surgical interventions as part of the care and treatment, including making a diagnosis, obtaining adequate venous access, performing a surgical resection for solid tumors (with staging and reconstruction), performing procedures for cancer prevention and its late effects, and managing complications of treatment; all with the goal of improving survival and quality of life. It is important for surgeons to adhere to sound pediatric surgical oncology principles, as they are closely associated with improved local control and survival. Unfortunately, there is a significant disparity in survival rates in low and middle income countries, when compared to those from high income countries. The International Society of Paediatric Surgical Oncology (IPSO) is the leading organization that deals with pediatric surgical oncology worldwide. This organization allows experts in the field from around the globe to gather and address the surgical needs of children with cancer. IPSO has been invited to contribute surgical guidance as part of the World Health Organization Initiative for Childhood Cancer. One of our goals is to provide surgical guidance for different scenarios, including those experienced in High- (HICs) and Low- and Middle-Income Countries (LMICs). With this in mind, the following guidelines have been developed by authors from both HICs and LMICs. These have been further validated by experts with the aim of providing evidence-based information for surgeons who care for children with cancer. We hope that this initiative will benefit children worldwide in the best way possible. Simone Abib, IPSO President Justin T Gerstle, IPSO Education Committee Chair Chan Hon Chui, IPSO Secretary.