Relationship between tumor response at therapy completion and prognosis in patients with Group III rhabdomyosarcoma: A report from the Children's Oncology Group

Children's Oncology Group's 2023 blueprint for research: Surgery

Surgery plays a crucial role in the treatment of children with solid malignancies. A well-conducted operation is often essential for cure. Collaboration with the primary care team is important for determining if and when surgery should be performed, and if performed, an operation must be done in accordance with well-established standards. The long-term consequences of surgery also need to be considered. Indications and objectives for a procedure vary. Providing education and developing and analyzing new research protocols that include aims relevant to surgery are key objectives of the Surgery Discipline of the Children's Oncology Group. The critical evaluation of emerging technologies to ensure safe, effective procedures is another key objective. Through research, education, and advancing technologies, the role of the pediatric surgeon in the multidisciplinary care of children with solid malignancies will continue to evolve.

Critical elements of pediatric rhabdomyosarcoma surgery

Rhabdomyosarcoma (RMS), the most common soft tissue sarcoma in children, requires multimodal therapy which is determined by risk group stratification. Local control may be achieved by surgical resection, radiation, or both. Resection may occur upfront or following induction chemotherapy as a delayed primary excision. An R1 resection may allow a reduction in radiation exposure; however, debulking is not indicated nor is excision of residual masses at the end of therapy. Regional lymph node assessment is an important component of surgical care, as positive nodal basins require radiation. Depending on the tumor site and biology, sentinel lymph node biopsy vs biopsy of clinically or radiographically concerning nodes is indicated. Therapeutic lymph node dissection is never indicated. Familiarity with site-specific oncologic principles for RMS and participation in a multidisciplinary team including Pediatric Oncology and Radiation Oncology are necessary components of surgical care to ensure optimal outcomes.

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.

Frequency and Clinical Course of Residual Orbital Masses After Treatment of Orbital Rhabdomyosarcoma

PURPOSE

To evaluate the frequency and clinical course of residual orbital masses on imaging studies after multimodality treatment for orbital rhabdomyosarcoma.

DESIGN

Retrospective case series.

METHODS

We reviewed records of patients with primary orbital rhabdomyosarcoma who underwent chemotherapy and radiotherapy after surgical biopsy or debulking at 4 US centers during 1998-2019. Demographics, histologic subtype, tumor response 12 weeks after chemotherapy initiation and after completion of all treatment, and imaging findings were analyzed.

RESULTS

Thirty-two patients met inclusion criteria. Twenty-two were male, and 30 were younger than 18 years. Histologic subtype was embryonal in 22 patients, alveolar in 8, and mixed embryonal/alveolar in 2. Median follow-up time was 46 months (range, 4.9-199 months). Two patients died. Twenty-seven patients had reliable end-of-treatment imaging findings, of whom 9 had a residual mass. Three residual masses disappeared spontaneously (by 4, 32, and 53 months), 2 remained at last contact, at 2 and 7 years of follow-up, and 3 were excised; 1 progressed and underwent an exenteration. Complete response at 12 weeks was associated with complete response at the end of treatment (P < .001). Patients with T1 or T2 tumor at presentation were more likely to have complete response at last contact than were those with T3 or T4 tumor (P < .05). Biopsy type (incisional or excisional) was not associated with response to treatment at any time point.

CONCLUSION

A residual orbital mass on imaging may be present after multimodality treatment in approximately one-third of patients. Resolution without biopsy or excision varied from months to years.

Durability of oncological outcomes of combination chemotherapy as a monotherapy for a select patient subset with non-metastatic non-alveolar bladder/prostate rhabdomyosarcoma

INTRODUCTION AND OBJECTIVES

We aim to assess the long-term oncological outcomes of children with bladder/prostate rhabdomyosarcoma (B/P RMS) treated with multiagent chemotherapy as a monotherapy. We hypothesize that a highly select patient subset can be treated with multiagent chemotherapy as a monotherapy and spared the morbidity of local treatment with similar oncological outcomes.

METHODS

Patients (≤21-year-old) treated for non-metastatic non-alveolar B/P RMS at a tertiary center and followed for>one year, were retrospectively reviewed. After pathological confirmation, patients received 12 weeks of induction VAC chemotherapy (IC) followed by second-look biopsies. Between 1996 and 2006 (group A), patients with>50% tumor size reduction and negative second-look biopsies following IC were spared local treatment and followed-up closely. Between 2007 and 2020 (group B), local treatment was routinely given at 12 weeks according to the COG protocols, irrespective of IC response. For all patients, consolidation chemotherapy was administered for additional 12-18 months.

RESULTS

Between 1996 and 2020, 27 patients (10 stage II, 17 stage III) with a median age of 3(1-21) years were included. Median follow-up was 87.5(15.3-247.1) months. Among 15 patients in group A, 3 were ineligible for the monotherapy protocol and received local treatment. The remaining 12 patients [9 complete (CR) and 3 incomplete response (IR) to IC] were treated exclusively with chemotherapy, of whom 9 were alive free of relapse at last follow-up. Two patients with IR to IC had disease relapse: one had pulmonary relapse at 8.2 months and one had local relapse at 35 months. The 5-year OS and EFS of group A were 86.7% and 80%, respectively. Analyzing survival according to IC response, CR to IC was achieved in 10 patients (9 group A and one group B) and was associated with significantly better OS and EFS than IR(p = 0.026 and 0.004, respectively) (Summary figure). All patients with CR to IC were alive free of relapse at last follow-up.

DISCUSSION

Treatment of RMS is traditionally multimodal. Local treatment of B/P RMS is associated with significant patient morbidity. In this study, CR to IC predicted better OS and EFS. Patients who achieved CR (radiological and pathological) to IC remained alive free of relapse irrespective of local treatment.

CONCLUSIONS

Our results suggest that patients with non-metastatic non-alveolar B/P RMS who achieve CR to IC can be treated with combination chemotherapy as a monotherapy and spared the morbidity of local treatment with durable survival outcomes. Prospective validation in a larger patient cohort is needed to support our hypothesis.

Management of Rhabdomyosarcoma in Pediatric Patients

Rhabdomyosarcoma is the commonest soft tissue sarcoma in children. Clinicians need vigilance to recognize the different signs and symptoms this tumor can present with because of variable sites of origin. Diagnosis requires a safe biopsy that obtains sufficient tissue for pathologic, genetic, and biological characterization of the tumor. Treatment depends on accurate staging with imaging and surgical sampling of draining lymph nodes. A multidisciplinary team assigns patients to risk-based therapy. Patients require chemotherapy and usually a combination of complex, site-specific surgery and/or radiotherapy. Outcomes for localized rhabdomyosarcoma continue to improve but new treatments are required for metastatic and relapsed disease.

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.

Utility of [18F] Fluoro-Deoxyglucose Positron Emission Tomography/Computed Tomography for Staging and Therapy Response Evaluation in Pediatric Rhabdomyosarcoma: A Case Series and Literature Review

Background: The role of [¹⁸F] fluoro-deoxyglucose [[¹⁸F] FDG] positron emission tomography (PET)/computed tomography (CT) in pediatric rhabdomyosarcoma (RMS) is not well-established. This manuscript explores the role of staging and therapy response evaluation of PET/CT in a series of patients with RMS.

Methods: Thirteen consecutive patients with pathologically proven RMS underwent baseline PET/CT scan and a second PET/CT for evaluation of therapy response. Maximum standardized uptake value (SUV_max), mean standardized uptake value (SUV_mean), highest standardized uptake peak value (SUV_peak), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were obtained from baseline PET/CT and were used as potential predictors for evaluation of metabolic treatment response.

Results: On baseline PET/CT, most RMSs are located in the pelvic cavity, and upper arms ranked second. The primary lesions were large and showed invasion to the surrounding tissues. Lymph node metastases were seen in eight patients, and eight patients showed distant metastasis to the lung, liver, and bone. The median SUV_max, SUV_mean, and SUV_peak of primary sites were 7.1, 4.0, and 5.9, respectively. The median MTV and TLG were 196.6 cm³ and 780.2, respectively. After therapy, six patients received complete metabolic response (CMR) and non-CMR occurred in seven patients on the second PET/CT. SUV_max, SUV_peak, MTV, and TLG in patients with CMR were significantly lower than those in patients with non-CMR.

Conclusions: Primary sites and metastatic lesions of RMS demonstrate increased glycolytic activity, which may allow them to be imaged using [¹⁸F] FDG PET/CT. Metabolic parameters derived from the baseline PET/CT have potential value for predicting CMR to therapy in pediatric RMS.

Radiation therapy is an important factor to improve survival in pediatric patients with head and neck rhabdomyosarcoma by enhancing local control: a historical cohort study from a single center

Background

The purpose of this study is to analyze the influence of radiation therapy on survival in a historical cohort of 56 pediatric patients with head and neck rhabdomyosarcoma.

Methods

A historical cohort of 56 pediatric patients with head and neck rhabdomyosarcoma from June 1st, 2013 to June 30th, 2019 was chosen. Clinical data and follow up results were collected including all diagnosis, treatment and prognosis information. Overall survival (OS) and event free survival (EFS) as time-to-event distributions were estimated with Kaplan-Meier method, and univariate analysis was performed with log rank test to detect differences between groups. Multivariate analysis was performed to explore the risk factors for survival with Cox proportional hazard model.

Results

The media follow up time of all 56 patients was 31.8 months (range 3.5–74.6 months). There were 26 events during follow up, including 14 disease progressions and 12 relapses. The estimated 5-year OS of all patients was 69.9%, and the estimated 5-year EFS was 48.8%. Patients with radiation therapy as a component of the initial treatment plan had better 5-year OS and EFS compared with those without radiation therapy (OS 80.3% vs. 49.7%, p = 0.003 and EFS 63.9% vs. 21.9%, p < 0.001). In patients with events, those who received salvage radiation therapy had better 5-year OS compared with those who didn’t (OS 66.0% vs. 31.2%, p = 0.033). On multivariate analysis, tumor size > 5 cm and non-initial radiation therapy were independent risk factors for OS in all patients, non-initial radiation therapy was an independent risk factor for EFS in all patients, and tumor size > 5 cm was an independent risk factor for OS in patients with events.

Conclusions

Radiation therapy as a component of initial treatment can improve the OS and EFS in pediatric head and neck rhabdomyosarcoma patients by enhancing local control, and non-initial radiation therapy is an independent risk factor for OS and EFS. Salvage radiation therapy still can improve OS in patients with disease progression and relapse. Tumor size > 5 cm is an independent risk factor for OS in pediatric HNRMS patients with or without disease progression/relapse.