A multi-institutional phase 2 trial of stereotactic body radiotherapy in the treatment of bone metastases in pediatric and young adult patients with sarcoma

Disease Control and Toxicity Outcomes after Stereotactic Ablative Radiation Therapy for Recurrent and/or Metastatic Cancers in Young-Adult and Pediatric Patients

BACKGROUND

Pediatric patients with metastatic and/or recurrent solid tumors have poor survival outcomes despite standard-of-care systemic therapy. Stereotactic ablative radiation therapy (SABR) may improve tumor control. We report the outcomes with the use of SABR in our pediatric solid tumor population.

METHODS

This was a single-institutional study in patients < 30 years treated with SABR. The primary endpoint was local control (LC), while the secondary endpoints were progression-free survival (PFS), overall survival (OS), and toxicity. The survival analysis was performed using Kaplan-Meier estimates in R v4.2.3.

RESULTS

In total, 48 patients receiving 135 SABR courses were included. The median age was 15.6 years (interquartile range, IQR 14-23 y) and the median follow-up was 18.1 months (IQR: 7.7-29.1). The median SABR dose was 30 Gy (IQR 25-35 Gy). The most common primary histologies were Ewing sarcoma (25%), rhabdomyosarcoma (17%), osteosarcoma (13%), and central nervous system (CNS) gliomas (13%). Furthermore, 57% of patients had oligometastatic disease (≤5 lesions) at the time of SABR. The one-year LC, PFS, and OS rates were 94%, 22%, and 70%, respectively. No grade 4 or higher toxicities were observed, while the rates of any grade 1, 2, and 3 toxicities were 11.8%, 3.7%, and 4.4%, respectively. Patients with oligometastatic disease, lung, or brain metastases and those who underwent surgery for a metastatic site had a significantly longer PFS. LC at 1-year was significantly higher for patients with a sarcoma histology (95.7% vs. 86.5%, p = 0.01) and for those who received a biological equivalent dose (BED10) > 48 Gy (100% vs. 91.2%, p = 0.001).

CONCLUSIONS

SABR is well tolerated in pediatric patients with 1-year local failure and OS rates of <10% and 70%, respectively. Future studies evaluating SABR in combination with systemic therapy are needed to address progression outside of the irradiated field.

Impact of Consolidative Radiation on Overall and Progression-Free Survival in Pediatric, Adolescent, and Young Adult Metastatic Bone and Soft Tissue Sarcoma

PURPOSE

To determine the association between consolidative radiation (RT) and survival in children, adolescents, and young adults with metastatic sarcoma.

METHODS AND MATERIALS

Eligibility criteria included patients aged ≤39 years with newly diagnosed metastatic bone or soft tissue sarcoma who completed local control of the primary tumor without disease progression. Consolidative RT was defined as RT to all known sites of metastatic disease. The Kaplan-Meier method was used to estimate overall survival (OS) and progression-free survival (PFS). The least absolute shrinkage and selection operator Cox provided adjusted estimates. To account for immortal time bias, consolidative RT was used as a time-varying covariate in a time dependent Cox model. Distant failure was estimated using the Fine-Gray model.

RESULTS

Patients (n = 85) had a median age at diagnosis of 14.8 years. Most common histology was Ewing Sarcoma (45.9%) followed by rhabdomyosarcoma (40.0%). Receipt of consolidative RT was associated with Ewing Sarcoma (P < .001) and local control modality as those who underwent local control with surgery and RT compared with surgery alone were more likely to be treated with consolidative RT (P = .034). Consolidative RT was independently associated with improved OS (hazard ratio [HR], 0.41; 95% CI, 0.17-0.98; P = .045) and improved PFS (HR, 0.37; 95% CI, 0.16-0.88; P = .024) after adjusting for confounding variables and immortal time bias. Patients treated with consolidative RT also experienced a lower risk of distant failure (HR, 0.33; 95% CI, 0.17-0.64; P = .001). In an independent data set of patients with metachronous progression (n = 36), consolidative RT remained independently associated with improved OS.

CONCLUSIONS

Consolidative RT was independently associated with improved OS and PFS and decreased risk of distant failure in child, adolescent, and young adult patients with metastatic sarcoma. Future work should evaluate biomarkers to optimize patient selection, timing, and dose for consolidative RT.

Improved local control following dose-escalated stereotactic ablative radiation therapy (SABR) for metastatic sarcomas: An international multi-institutional experience

BACKGROUND

We aimed to characterize local control (LC) and overall survival (OS) following stereotactic ablative radiation therapy (SABR) for extracranial sarcoma metastases.

METHODS

A prospectively-maintained institutional registry was queried for patients with metastases from sarcoma primaries managed with SABR. Kaplan-Meier analysis was utilized for univariate analyses to assess potential prognostic factors regarding LC and OS. A Cox proportional hazards multivariate (MVA) model was employed to further assess initially identified independent variables.

RESULTS

A total of 94 patients with 118 lesions with LC information were identified. Common metastatic sites treated were lung (77), non-spinal bone (15), and spine (10). The median biologically effective dose (BED4) was 175 Gy4 (range56.3 Gy4-360 Gy4) with a median dose/fractionation schedule of 50 Gy/5 fractions. One- and 2-year OS rates were 81.3 % (95 % CI: 71.2-88.1 %6) and 50.5 % (95 % CI: 38.6-61.3 %, respectively. On Cox MVA, advanced age and non-lung metastases were associated with inferior OS (p < 0.03) with patients with 0-2 of these risk factors having estimated 2-year OS of 65.1 %, 38.9 %, and N/A, respectively. One- and 2-year LC rates were 85.3 % (95 % CI: 77.7-90.9 %) and 78.2 % (95 % CI: 67.9-85.6 %), respectively. On MVA, only BED4 < 175 Gy was associated with inferior LC (hazard ratio (HR) = 3.33; p = 0.01). Ten of 118 treated lesions had treatment-related toxicities (all Grade 1-2).

CONCLUSION

Age and lung vs. non-lung metastases were prognostic of OS and should be considered in patient selection for SABR. Dose escalation when feasible with BED4 ≥ 175 Gy is recommended given durable LC achieved without a subsequent increase in toxicity.

Consensus recommendations in the management of Ewing sarcoma from the National Ewing Sarcoma Tumor Board

Ewing sarcoma (ES) is a malignant tumor of bone and soft tissue that most often occurs in adolescents and young adults. Despite an international coordinated approach, several nuances, discrepancies, and debates remain in defining the standard of care for treating ES. In this review, the authors leverage the expertise assembled by formation of the National Ewing Sarcoma Tumor Board, a multi-institution, multidisciplinary virtual tumor board that meets monthly to discuss complicated and challenging cases of ES. This report is focused on select topics that apply to the management of patients with newly diagnosed ES. The specific topics covered include indications for bone marrow aspirate and biopsy for initial evaluation compared with fluorodeoxyglucose-positron emission tomography, the role of interval compressed chemotherapy in patients aged 18 years and older, the role of adding ifosfamide/etoposide to vincristine/doxorubicin/cyclophosphamide for patients with metastatic disease, the data on and role of high-dose chemotherapy with autologous stem cell transplantation, maintenance therapy, and whole-lung irradiation. The data referenced are often limited to subgroup analyses and/or compiled from multiple sources. Although not intended to replace the clinical judgement of treating physicians, the guidelines are intended to provide clarity and recommendations for the upfront management of patients with ES. PLAIN LANGUAGE SUMMARY: Ewing sarcoma is a malignant tumor of bone and soft tissue that most often occurs in adolescents and young adults. For this review, the authors used the experience of the National Ewing Sarcoma Tumor Board, a multi-institution, multidisciplinary virtual tumor board that meets monthly to discuss complicated and challenging cases of Ewing sarcoma. Although not intended to replace the clinical judgement of treating physicians, the guidelines will focus on the development of consensus statements for the upfront management of patients with Ewing sarcoma.

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.

Local Therapies for Metastatic Sarcoma: Why, When, and How?

Management of patients with advanced sarcoma has been evolving in recent decades, from a one-fit-all perspective to a more refined, personalized, and multidisciplinary approach. In parallel, the evolution of local therapies (radiotherapy, surgical and interventional radiology techniques) has contributed to the improvement of survival of patients with advanced sarcoma. In this article, we review the evidence regarding local treatments in advanced sarcoma, as well as its integration with systemic therapies, to provide the reader a wider and deeper perspective on the management of patients with metastatic sarcoma.

Palliative radiotherapy for children: Symptom response and treatment-associated toxicity according to radiation therapy dose and fractionation

BACKGROUND/OBJECTIVES

Radiotherapy is an effective palliative treatment in advanced cancer. Shorter palliative treatment courses are recommended for adults, though pediatric data addressing treatment efficacy and toxicity according to radiation therapy (RT) dose and fractionation are limited.

DESIGN/METHODS

Total 213 patients aged 21 years or younger receiving 422 palliative radiotherapy treatment courses from 2003 to 2016 were included. Symptom response and treatment-associated toxicity were recorded and analyzed in relationship to demographic and treatment variables.

RESULTS

Common diagnoses included sarcoma (32.5%), neuroblastoma (24.9%), leukemia/lymphoma (14.9%), and central nervous system tumors (10.9%). The most common indication for treatment was pain (46.7%). Patients received a median of 10 fractions, 2.5 Gy dose per fraction, and 21 Gy total dose. Number of RT fractions was five or less in 166 (39.3%), six to 10 fractions in 117 (27.2%), and 10 or more fractions in 139 (32.9%) of courses. Complete or partial pain relief was achieved in 85% (151 of 178 evaluable patients), including 77.8% receiving five or less fractions and 89.6% receiving more than five fractions. Highest toxicity was grade 1 in 159 (38.9%), grade 2 in 26 (6.4%), and grade 3 in two (0.5%) treatments. On multivariable analysis, RT delivered 30 or more days from death (OR 12.13, 95% CI: 2.13-69.2, p = .005) and no adjuvant chemotherapy (OR 0.14, 95% CI: 0.03-0.54, p = .005) were significantly associated with pain response, and five or less fractions were significantly associated with lower toxicity (OR 0.24, 95% CI: 0.06-0.97, p = .045).

CONCLUSIONS

Palliative RT courses of five or less fractions result in high rates of pain control and are associated with low toxicity in pediatric patients with cancer.

Stereotactic body radiotherapy for metastatic sarcoma to the lung: adding to the arsenal of local therapy

INTRODUCTION

Conventional treatment of pulmonary metastatic sarcoma primarily involves surgery, with systemic therapy added in select patients. However, broader applications of radiation therapy techniques have prompted investigation into the use of stereotactic body radiotherapy (SBRT) for treatment of metastatic sarcoma, an attractive non-invasive intervention with potential for lower rates of adverse events than surgery. Current data are limited to retrospective analyses. This study analyzed 2-year local control and overall survival and adverse events in patients prospectively treated with SBRT to pulmonary sarcoma metastases.

METHODS

Patients prospectively treated with SBRT to the lung for biopsy-proven metastatic sarcoma at a single institution from 2010 to 2022 were included. SBRT dose/fractionation treatment regimens ranged from 34 to 54 Gy in 1-10 fractions using photons. Local recurrence, local progression-free survival (LPFS) and overall survival (OS) were calculated from the end of SBRT. Univariable analysis (UVA) was performed using the log-rank test. Multivariable analysis (MVA) was performed using the Cox proportional hazards model. Adverse events due to SBRT were graded based on the Common Terminology Criteria for Adverse Events, version 4.0.

RESULTS

Eighteen patients with metastatic sarcoma were treated to 26 pulmonary metastases. The median local progression-free survival was not met. The median overall survival was not met. The local control rate at 2 years was 96%. 2-year LPFS was 95.5% and OS was 74%. Three patients (16.7%) developed grade 1 adverse events from SBRT. There were no adverse events attributed to radiation that were grade 2 or higher.

CONCLUSION

We report prospective data demonstrating that SBRT for sarcoma pulmonary metastases affords a high rate of local control and low toxicity, consistent with prior sarcoma SBRT retrospective data. This study adds to the wealth of information on SBRT in a radioresistant tumor. Though largely limited to retrospective reviews, current data indicate high rates of local control with favorable toxicity profiles. Therefore, SBRT for pulmonary sarcoma metastases may be considered for properly selected patients.

Efficacy and Safety of Stereotactic Body Radiation Therapy for Pediatric Malignancies: The LITE-SABR Systematic Review and Meta-Analysis

Purpose

Limited data are currently available on clinical outcomes after stereotactic body radiation therapy (SBRT) for pediatric and adolescent and young adult (AYA) patients with cancer. We aimed to perform a systematic review and study-level meta-analysis to characterize associated local control (LC), progression-free survival (PFS), overall survival, and toxicity after SBRT.

Methods and Materials

Relevant studies were queried using a Population, Intervention, Control, Outcomes, Study Design (PICOS)/Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)/Meta-analysis of Observational Studies in Epidemiology (MOOSE) selection criteria. Primary outcomes were 1-year and 2-year LC as well as incidence of acute and late grade 3 to 5 toxicities, with secondary outcomes of 1-year overall survival and 1-year PFS. Outcome effect sizes were estimated with weighted random effects meta-analyses. Mixed-effects weighted regression models were performed to examine potential correlations between biologically effective dose (BED₁₀), LC, and toxicity incidence.

Results

Across 9 published studies, we identified 142 pediatric and AYA patients with 217 lesions that were treated with SBRT. Estimated 1-year and 2-year LC rates were 83.5% (95% confidence interval, 70.9%-96.2%) and 74.0% (95% CI, 64.6%-83.4%), respectively, with an estimated acute and late grade 3 to 5 toxicity rate of 2.9% (95% CI, 0.4%-5.4%; all grade 3). The estimated 1-year OS and PFS rates were 75.4% (95% CI, 54.5%-96.3%) and 27.1% (95% CI, 17.3%-37.0%), respectively. On meta-regression, higher BED₁₀ was correlated with improved 2-year LC with every 10 Gy₁₀ increase in BED₁₀ associated with a 5% improvement in 2-year LC (P = .02) in sarcoma-predominant cohorts.

Conclusions

SBRT provided durable LC for pediatric and AYA patients with cancer with minimal severe toxicities. Dose escalation may result in improved LC for sarcoma-predominant cohorts without a subsequent increase in toxicity. However, further investigations with patient-level data and prospective inquiries are indicated to better define the role of SBRT based on patient and tumor-specific characteristics.

Clinical outcomes and efficacy of stereotactic body radiation therapy in children, adolescents, and young adults with metastatic solid tumors

OBJECTIVE

The objective of this study is to report disease outcomes and toxicity with the use of stereotactic body radiation therapy (SBRT) in the treatment of pediatric metastatic disease.

METHODS

All pediatric and adolescent young adult (AYA) patients' who received SBRT were included between the years 2000 and 2020. Study endpoints included local control (LC), progression-free survival (PFS), overall survival (OS), cumulative incidence (CI) of death or local failure and toxicity. The end points with respect to survival and LC were calculated using the Kaplan-Meier estimate. The cumulative incidence of local failure was calculated using death as a competing risk.

RESULTS

16 patients with 36 lesions irradiated met inclusion criteria and formed the study cohort. The median OS and PFS for the entire cohort were 17 months and 15.7 months, respectively. The 1 year OS for the entire cohort was 75%. The 6- and 12 month local control was 85 and 78%, respectively. There were no local failures in irradiated lesions for patients who received a BED10≥100 Gy. Patients who were treated with SBRT who had ≤5 metastatic lesions at first recurrence had a superior 1 year OS of 100 vs 50% for those with >5 lesions. One patient (6.3%) experienced a Grade 3 central nervous system toxicity.

CONCLUSION

LC was excellent with SBRT delivered to metastatic disease, particularly for lesions receiving a BED10≥100 Gy. High-grade toxicity was rare in our patient population. Patients with five or fewer metastatic sites have a significantly better OS compared to >5 sites.

ADVANCES IN KNOWLEDGE

This study demonstrates that SBRT is safe and efficacious in the treatment of pediatric oligometastatic disease.

"Per protocol" practice patterns for Children's Oncology Group trials within the radiation oncology community

Little is known about the prevalence of pediatric radiation oncologists treating patients off study according to Children's Oncology Group (COG) trials before data are available regarding toxicity and efficacy of novel radiotherapy regimens. We conducted a 12-question survey of 358 pediatric radiation oncologists to characterize practice patterns regarding ongoing and completed COG protocols off study. With 130 responses (40.3%), the prevalence of providing treatment per protocol, but off study, before data are available in abstract or peer-reviewed form varied from 9.1% (for ACNS1422) to 88.1% (for AHOD1331). Future studies are needed to understand the effects of these practice patterns on outcomes.

The Evolving Role of Radiotherapy for Pediatric Cancers With Advancements in Molecular Tumor Characterization and Targeted Therapies

Ongoing rapid advances in molecular diagnostics, precision imaging, and development of targeted therapies have resulted in a constantly evolving landscape for treatment of pediatric cancers. Radiotherapy remains a critical element of the therapeutic toolbox, and its role in the era of precision medicine continues to adapt and undergo re-evaluation. Here, we review emerging strategies for combining radiotherapy with novel targeted systemic therapies (for example, for pediatric gliomas or soft tissue sarcomas), modifying use or intensity of radiotherapy when appropriate via molecular diagnostics that allow better characterization and individualization of each patient’s treatments (for example, de-intensification of radiotherapy in WNT subgroup medulloblastoma), as well as exploring more effective targeted systemic therapies that may allow omission or delay of radiotherapy. Many of these strategies are still under investigation but highlight the importance of continued pre-clinical and clinical studies evaluating the role of radiotherapy in this era of precision oncology.

Radiation Therapy in Metastatic Soft Tissue Sarcoma: From Palliation to Ablation

Simple Summary

In the United States, over 13,000 patients are diagnosed with soft tissue sarcoma annually leading to over 5000 deaths per year despite aggressive treatments including radiotherapy, surgery, and chemotherapy. Although the majority of patients present with localized disease, unfortunately many will develop metastatic disease, which is generally not curable. There is growing evidence that local ablative therapies may be beneficial in patients with a variety of metastatic malignancies. In this review article, we explore the evolving role of radiotherapy in patients with metastatic soft tissue sarcoma. In particular, we review the growing role of ablative radiotherapy for oligometastatic disease, local control of the primary site, and palliation.

Abstract

The management of patients with metastatic cancer is rapidly changing. Historically, radiotherapy was utilized for the treatment of localized disease or for palliation. While systemic therapy remains the mainstay of management for patients with metastatic cancer, radiotherapy is becoming increasingly important not only to palliate symptoms, but also to ablate oligometastatic or oligoprogressive disease and improve local control in the primary site. There is emerging evidence in multiple solid malignancies that patients with low volume metastatic disease that undergo local ablative therapy to metastatic sites may have improved progression free survival and potentially overall survival. In addition, there is increasing evidence that select patients with metastatic disease may benefit from aggressive treatment of the primary site. Patients with metastatic soft tissue sarcoma have a poor overall prognosis. However, there may be opportunities in patients with low volume metastatic soft tissue sarcoma to improve outcomes with local therapy including surgery, ablation, embolization, and radiation therapy. Stereotactic body radiation therapy (SBRT) offers a safe, convenient, precise, and non-invasive option for ablation of sites of metastases. In this review article, we explore the limited yet evolving role of radiotherapy to metastatic and primary sites for local control and palliation, particularly in the oligometastatic setting.

Out-of-field dose in stereotactic radiotherapy for paediatric patients

Background and purpose

Stereotactic radiotherapy combines image guidance and high precision delivery with small fields to deliver high doses per fraction in short treatment courses. In preparation for extension of these treatment techniques to paediatric patients we characterised and compared doses out-of-field in a paediatric anthropomorphic phantom for small flattened and flattening filter free (FFF) photon beams.

Method and materials

Dose measurements were taken in several organs and structures outside the primary field in an anthropomorphic phantom of a 5 year old child (CIRS) using thermoluminescence dosimetry (LiF:Mg,Cu,P). Out-of-field doses from a medical linear accelerator were assessed for 6 MV flattened and FFF beams of field sizes between 2 × 2 and 10 × 10 cm².

Results

FFF beams resulted in reduced out-of-field doses for all field sizes when compared to flattened beams. Doses for FFF and flattened beams converged for all field sizes at larger distances (>40 cm) from the central axis as leakage becomes the primary source of out-of-field dose. Rotating the collimator to place the MLC bank in the longitudinal axis of the patient was shown to reduce the peripheral doses measured by up to 50% in Varian linear accelerators.

Conclusion

Minimising out-of-field doses by using FFF beams and aligning the couch and collimator to provide tertiary shielding demonstrated advantages of small field, FFF treatments in a paediatric setting.