Preliminary results of a phase II trial of proton radiotherapy for pediatric rhabdomyosarcoma

Radiotherapy management of paediatric cancers with synchronous metastasis

Cancer in childhood represent 1% of all the new diagnosed cancers. About 30% of children with cancer receive radiation therapy, representing about 600 to 700 patients per year in France. As a consequence, paediatric cancers with synchronous metastasis is a very rare situation in oncology, with usually poor standard of care. However, considerable efforts are made by paediatric oncology scientific societies to offer trials or treatment consensus despite these rare situations. The article proposes to synthesize the radiotherapy management of both primary tumour and synchronous metastasis in the most "common" childhood or adolescent cancers.

Which Patients With Rhabdomyosarcoma Need Radiotherapy? Analysis of the Radiotherapy Strategies of the CWS-96 and CWS-2002P Studies and SoTiSaR Registry

PURPOSE

To analyze and compare the indications, doses, and application methods of radiotherapy (RT) and their influence on prognosis of patients with localized rhabdomyosarcoma (RMS).

METHODS

One thousand four hundred seventy patients with localized RMS 21 years and younger entered on CWS-96, CWS-2002P, and SoTiSaR were eligible for the analysis. The median follow-up was 6.5 years (IQR, 3.3-9.5).

RESULTS

The 5-year event-free survival (EFS) and local control survival (LCS) for 910 (62%) irradiated versus nonirradiated patients were 71% versus 69% and 78% versus 73% (P = .03), respectively. Ninety-five percent of patients in IRS I (90% embryonal RMS [eRMS]) were nonirradiated (EFS, 87%). Irradiated patients with IRS II had improved LCS (91% v 80%; P = .01) and EFS (not significant). In IRS III, EFS and LCS were significantly better for RT patients: 71% versus 56% (P = 3.1e-06) and 76% versus 61% (P = 4.1e-07). Patients with tumors in the head and neck region (orbita, parameningeal, and nonparameningeal) and in other sites had significantly better EFS and LCS and in parameningeal also overall survival (OS). The efficacy of low RT doses of 32 Gy (hyperfractionated, accelerated RT [HART]) and 36 and 41.4 Gy (conventional fractionated RT [CFRT]) in the favorable groups and higher doses of 44.8 Gy (HART) and 50.4 and 55.4 Gy (CFRT) in the unfavorable groups was comparable. Proton RT was used predominantly in head/neck-parameningeal (HN-PM) tumors, with similar EFS and LCS to photon RT.

CONCLUSION

RT can be omitted in patients with IRS I eRMS. RT improves LCS and EFS in IRS II and III. RT improves OS in patients with HN-PM, with proton RT comparable with photon RT. Doses of 32 Gy (HART) or 36 and 41.4 Gy (CFRT) had comparable efficacy in patients with favorable risk profiles and 44.8 Gy (HART) or 50.4 and 55.8 Gy (CFRT) in the unfavorable groups.

Mitigating Radiotoxicity in the Central Nervous System: Role of Proton Therapy

OPINION STATEMENT

Central nervous system (CNS) radiotoxicity remains a challenge in neuro-oncology. Dose distribution advantages of protons over photons have prompted increased use of brain-directed proton therapy. While well-recognized among pediatric populations, the benefit of proton therapy among adults with CNS malignancies remains controversial. We herein discuss the role of protons in mitigating late CNS radiotoxicities in adult patients. Despite limited clinical trials, evidence suggests toxicity profile advantages of protons over conventional radiotherapy, including retention of neurocognitive function and brain volume. Modelling studies predict superior dose conformality of protons versus state-of-the-art photon techniques reduces late radiogenic vasculopathies, endocrinopathies, and malignancies. Conversely, potentially higher brain tissue necrosis rates following proton therapy highlight a need to resolve uncertainties surrounding the impact of variable biological effectiveness of protons on dose distribution. Clinical trials comparing best photon and particle-based therapy are underway to establish whether protons substantially improve long-term treatment-related outcomes in adults with CNS malignancies.

Clinical Insight on Proton Therapy for Paediatric Rhabdomyosarcoma

This paper offers an insight into the use of Proton Beam Therapy (PBT) in paediatric patients with rhabdomyosarcoma (RMS). This paper provides a comprehensive analysis of the literature, investigating comparative photon-proton dosimetry, outcome, and toxicity. In the complex and multimodal scenario of the treatment of RMS, clear evidence of the therapeutic superiority of PBT compared to other modern photon techniques has not yet been demonstrated; however, PBT can be considered an excellent treatment option, in particular for young children and patients with specific primary sites, such as the head and neck area (and especially the parameningeal regions), genito-urinary, pelvic, and paravertebral regions. The unique depth-dose characteristics of protons can be exploited to achieve significant reductions in normal tissue doses and may allow an escalation of tumour doses and greater sparing of normal tissues, thus potentially improving local control while at the same time reducing toxicity and improving quality of life. However, access of children with RMS (and more in general with solid tumors) to PBT remains a challenge, due to the limited number of available proton therapy installations.

Case Report: A 13-year-old adolescent diagnosed as malignant phyllodes tumor combined with rhabdomyosarcoma differentiation

Phyllodes tumor (PT) is an infrequent type of breast neoplasm, constituting a mere 0.5%-1.5% of the entirety of breast tumors. The malignant phyllodes tumor (MPT) comprises only 15% of all phyllodes tumors, and its transformation into rhabdomyosarcoma (RMS) is exceedingly rare in clinical practice. Given its insensitivity to chemotherapy and radiotherapy, treatment options for MPT patients are limited, leaving complete surgical resection as the only option. Therefore, it is imperative to investigate the effective utilization of the heterogeneous differentiation characteristics of MPT to expand treatment alternatives for these patients. In this case report, we represent a 13-year-old adolescent diagnosed with giant breast MPT with RMS differentiation and pulmonary metastasis. The initial step in the treatment process involved radical surgical resection, followed by the administration of four cycles of VDC/IC chemotherapy, which is widely recognized as the standard chemotherapy for RMS. Regrettably, the delay in initiating chemotherapy resulted in minimal observable changes in the size of the pulmonary metastatic nodule. Additionally, a comprehensive literature review on the characterization of MPT with heterogeneous differentiation was conducted to enhance comprehension of the diagnosis and treatment of this uncommon disease in clinical practice. Meanwhile, this case also reminds the doctors that when we diagnose a patient as MPT, it is crucial to consider its heterogenous nature and promptly initiate adjuvant treatment. By targeting the differentiation element of MPT, it becomes feasible to overcome the previously perceived limitation of surgical intervention as the sole treatment option.

Current topics and management of head and neck sarcomas

Given the low incidence, variety of histological types, and heterogeneous biological features of head and neck sarcomas, there is limited high-quality evidence available to head and neck oncologists. For resectable sarcomas, surgical resection followed by radiotherapy is the principle of local treatment, and perioperative chemotherapy is considered for chemotherapy-sensitive sarcomas. They often originate in anatomical border areas such as the skull base and mediastinum, and they require a multidisciplinary treatment approach considering functional and cosmetic impairment. Moreover, head and neck sarcomas may exhibit different behaviour and characteristics than sarcomas of other areas. In recent years, the molecular biological features of sarcomas have been used for the pathological diagnosis and development of novel agents. This review describes the historical background and recent topics that head and neck oncologists should know about this rare tumour from the following five perspectives: (i) epidemiology and general characteristics of head and neck sarcomas; (ii) changes in histopathological diagnosis in the genomic era; (iii) current standard treatment by histological type and clinical questions specific to head and neck; (iv) new drugs for advanced and metastatic soft tissue sarcomas; and (v) proton and carbon ion radiotherapy for head and neck sarcomas.

Spindle Cell Rhabdomyosarcoma of the Inguinal Region Mimicking a Complicated Hernia in the Adult-An Unexpected Finding

Rhabdomyosarcoma is a rare tumor that is diagnosed mostly in children and adolescents, rarely in adults, representing 2-5% of all soft tissue sarcomas. It has four subtypes that are recognized: embryonal (50%), alveolar (20%), pleomorphic (20%), and spindle cell/sclerosing (10%). The diagnosis of rhabdomyosarcoma is based on the histological detection of rhabdomyoblasts and the expression of muscle-related biomarkers. Spindle cell/sclerosing rhabdomyosarcoma consists morphologically of fusiform cells with vesicular chromatin arranged in a storiform pattern or long fascicles, with occasional rhabdomyoblasts. Also, dense, collagenous, sclerotic stroma may be seen more commonly in adults. We present a rare case of an adult who presented to the hospital with a tumor in the left inguinal area, was first diagnosed with a left strangulated inguinal hernia and was operated on as an emergency, although the diagnosis was ultimately a spindle cell rhabdomyosarcoma of the inguinal region.

Photon and Proton irradiation in Patient-derived, Three-Dimensional Soft Tissue Sarcoma Models

BACKGROUND

Despite their heterogeneity, the current standard preoperative radiotherapy regimen for localized high-grade soft tissue sarcoma (STS) follows a one fits all approach for all STS subtypes. Sarcoma patient-derived three-dimensional cell culture models represent an innovative tool to overcome challenges in clinical research enabling reproducible subtype-specific research on STS. In this pilot study, we present our methodology and preliminary results using STS patient-derived 3D cell cultures that were exposed to different doses of photon and proton radiation. Our aim was: (i) to establish a reproducible method for irradiation of STS patient-derived 3D cell cultures and (ii) to explore the differences in tumor cell viability of two different STS subtypes exposed to increasing doses of photon and proton radiation at different time points.

METHODS

Two patient-derived cell cultures of untreated localized high-grade STS (an undifferentiated pleomorphic sarcoma (UPS) and a pleomorphic liposarcoma (PLS)) were exposed to a single fraction of photon or proton irradiation using doses of 0 Gy (sham irradiation), 2 Gy, 4 Gy, 8 Gy and 16 Gy. Cell viability was measured and compared to sham irradiation at two different time points (four and eight days after irradiation).

RESULTS

The proportion of viable tumor cells four days after photon irradiation for UPS vs. PLS were significantly different with 85% vs. 65% (4 Gy), 80% vs. 50% (8 Gy) and 70% vs. 35% (16 Gy). Proton irradiation led to similar diverging viability curves between UPS vs. PLS four days after irradiation with 90% vs. 75% (4 Gy), 85% vs. 45% (8 Gy) and 80% vs. 35% (16 Gy). Photon and proton radiation displayed only minor differences in cell-killing properties within each cell culture (UPS and PLS). The cell-killing effect of radiation sustained at eight days after irradiation in both cell cultures.

CONCLUSIONS

Pronounced differences in radiosensitivity are evident among UPS and PLS 3D patient-derived sarcoma cell cultures which may reflect the clinical heterogeneity. Photon and proton radiation showed similar dose-dependent cell-killing effectiveness in both 3D cell cultures. Patient-derived 3D STS cell cultures may represent a valuable tool to enable translational studies towards individualized subtype-specific radiotherapy in patients with STS.

Efficacy and safety of proton beam therapy for rhabdomyosarcoma: a systematic review and meta-analysis

OBJECTIVE

This study aimed to evaluate and conduct a meta-analysis on the efficacy and safety of proton beam therapy (PBT) for rhabdomyosarcoma (RMS).

METHODS

We searched for articles using PubMed, Embase, Cochrane Library, and Web of Science databases from their inception to December 22, 2022. Two researchers independently screened literature and extracted data. Statistical analyses were performed using STATA version 14.0.

RESULTS

We got 675 candidate articles, of which 11 studies were included in our study according to the inclusion and exclusion criteria. Of the 544 RMS patients who received PBT. The local control (LC) rate at 1, 2, 3, 4, and 5 years were 96% (95% confidence interval (CI) 0.91-1.01), 93% (95% CI 0.86-1.00), 78% (95% CI 0.71-0.85), 85% (95% CI 0.78-0.92), and 84% (95% CI 0.74-0.95), respectively. The progression-free survival (PFS) rate at 1, 2, 3, 4, and 5 years were 82% (95% CI 0.72-0.92), 73% (95% CI 0.61-0.84), 63% (95% CI 0.47-0.79), 64% (95% CI 0.54-0.74), and 76% (95% CI 0.59-0.94), respectively. The overall survival (OS) rate at 1, 2, 3, 4, and 5 years were 93% (95% CI 0.86-1.00), 85% (95% CI 0.76-0.95), 80% (95% CI 0.63-0.96), 71% (95% CI 0.62-0.80), and 82% (95% CI 0.71-0.94), respectively. Acute and late toxicities were mainly grades 1 to 2 in all studies.

CONCLUSION

As an advantageous RT technique, PBT is an emerging option for patients with RMS, particularly children and adolescents patients. The data showed that PBT is a feasible, safe, and effective modality for RMS, showing promising LC, OS, PFS, and lower acute and late toxicities. PROSPERO registration number: CRD42022329154.

Treatment of spinal rhabdomyosarcoma in adults: A case report and literature review of current evidence

Spinal rhabdomyosarcoma (RMS) is a rare yet highly malignant tumor in adults. Literature on this entity is lacking and no mature treatment guideline is currently available. The treatment arsenals include surgery, radiotherapy and chemotherapy, being used singly or jointly. However, the prognosis is dismal, with a mean overall survival period of 10 months. Thus, any case of this disease with encouraging outcomes shall be shared. A case of a middle-aged female patient with spinal RMS was presented in the current report. The patient suffered from back pain but was neurologically intact. The patient underwent a total en-bloc spondylectomy of the T11-L2 vertebrae and spinal reconstruction with 3D-printed prosthetic vertebrae. Afterwards, the patient received a rigid schedule of stereotactic body radiotherapy (SBRT) and chemotherapy. To date, the patient has survived for 40 months, with the preservation of neurological function and sustained mitigation of local pain after the operation. The patient suffered subcutaneous colonization of tumor cells and pulmonary metastasis 10 months postoperatively, but obtained a long locoregional control of 19 months. In conclusion, total en-bloc lesion resection is indicated for the treatment of isolated, primary spinal RMS in adults. Some authors reported that the usage of new surgical tools and instruments has facilitated surgery, which was previously invasive and technically challenging. Advanced radiotherapy techniques, such as SBRT, which were proven effective for local lesion control, should be implemented early after the operation. Chemotherapy remains the mainstay of treatment, but further research and evidence for the efficacy of regimens specifically for adults are required.

Particle Therapy: Clinical Applications and Biological Effects

Particle therapy is a developing area of radiotherapy, mostly involving the use of protons, neutrons and carbon ions for cancer treatment. The reduction of side effects on healthy tissues in the peritumoral area is an important advantage of particle therapy. In this review, we analyze state-of-the-art particle therapy, as compared to conventional photon therapy, to identify clinical benefits and specify the mechanisms of action on tumor cells. Systematization of published data on particle therapy confirms its successful application in a wide range of cancers and reveals a variety of biological effects which manifest at the molecular level and produce the particle therapy-specific molecular signatures. Given the rapid progress in the field, the use of particle therapy holds great promise for the near future.

A novel stochastic optimization method for handling misalignments of proton and photon doses in combined treatments

Objective. Combined proton–photon treatments, where most fractions are delivered with photons and only a few are delivered with protons, may represent a practical approach to optimally use limited proton resources. It has been shown that, when organs at risk (OARs) are located within or near the tumor, the optimal multi-modality treatment uses protons to hypofractionate parts of the target volume and photons to achieve near-uniform fractionation in dose-limiting healthy tissues, thus exploiting the fractionation effect. These plans may be sensitive to range and setup errors, especially misalignments between proton and photon doses. Thus, we developed a novel stochastic optimization method to directly incorporate these uncertainties into the biologically effective dose (BED)-based simultaneous optimization of proton and photon plans. Approach. The method considers the expected value E b and standard deviation σ b of the cumulative BED b in every voxel of a structure. For the target, a piecewise quadratic penalty function of the form b min − E b − 2 σ b + 2 is minimized, aiming for plans in which the expected BED minus two times the standard deviation exceeds the prescribed BED b min . Analogously, E b + 2 σ b − b max + 2 is considered for OARs. Main results. Using a spinal metastasis case and a liver cancer patient, it is demonstrated that the novel stochastic optimization method yields robust combined treatment plans. Tumor coverage and a good sparing of the main OARs are maintained despite range and setup errors, and especially misalignments between proton and photon doses. This is achieved without explicitly considering all combinations of proton and photon error scenarios. Significance. Concerns about range and setup errors for safe clinical implementation of optimized proton–photon radiotherapy can be addressed through an appropriate stochastic planning method.

Local control of parameningeal rhabdomyosarcoma: An expert consensus guideline from the International Soft Tissue Sarcoma Consortium (INSTRuCT)

The International Soft Tissue Sarcoma Database Consortium (INSTRuCT) consists of a collaboration between the Children's Oncology Group (COG) Soft Tissue Sarcoma Committee, the European pediatric Soft Tissue Sarcoma Study Group (EpSSG), and the Cooperative Weichteilsarkom Studiengruppe (CWS). As part of the larger initiative of INSTRuCT to provide consensus expert opinions for clinical treatment of pediatric soft tissue sarcoma, we sought to provide updated, evidenced-based consensus guidelines for local treatment of parameningeal rhabdomyosarcoma using both existing literature as well as recommendations from the relevant cooperative group clinical trials. Overall, parameningeal rhabdomyosarcoma represents a distinctly challenging disease to treat, given its location near many critical structures in the head and neck, frequently advanced local presentation, and predilection for local failure. Definitive chemoradiation remains the standard treatment approach for parameningeal rhabdomyosarcoma, with surgery often limited to biopsy or salvage therapy for recurrent disease. In this consensus paper, we specifically discuss consensus guidelines and evidence for definitive local management with radiotherapy, with a focus on imaging for radiotherapy planning, dose and timing of radiation, approach for nodal irradiation, various radiation techniques, including proton therapy, and the limited role of surgical resection.

Optimizing Rhabdomyosarcoma Treatment in Adolescents and Young Adults

Rhabdomyosarcoma (RMS) is the most common form of soft tissue sarcoma in children, but can also develop in adolescents and young adults (AYA). The mainstay of treatment is multi-agent chemotherapy, ideally with concomitant local treatment, including surgical resection and/or radiation therapy. Although most treatment decisions for RMS in AYA are based on scientific evidence accumulated through clinical studies of pediatric RMS, treatment outcomes are significantly inferior in AYA patients than in children. Factors responsible for the significantly poor outcomes in AYA are tumor biology, the physiology specific to the age group concerned, refractoriness to multimodal treatments, and various psychosocial and medical care issues. The present review aims to examine the various issues involved in the treatment and care of AYA patients with RMS, discuss possible solutions, and provide an overview of the literature on the topic with several observations from the author's own experience. Clinical trials for RMS in AYA are the best way to develop an optimal treatment. However, a well-designed clinical trial requires a great deal of time and resources, especially when targeting such a rare population. Until clinical trials are designed and implemented, and their findings duly analyzed, we must provide the best possible practice for RMS treatment in AYA patients based on our own expertise in manipulating the dosage schedules of various chemotherapeutic agents and administering local treatments in a manner appropriate for each patient. Precision medicine based on state-of-the-art cancer genomics will also form an integral part of this personalized approach. In the current situation, the only way to realize such a holistic treatment approach is to integrate new developments and findings, such as gene-based diagnostics and treatments, with older, fundamental evidence that can be selectively applied to individual cases.

Japanese Orthopaedic Association (JOA) clinical practice guidelines on the management of soft tissue tumors 2020 - Secondary publication

BACKGROUND

These clinical practice guidelines are intended to provide recommendations based on the best evidence obtained to date on key issues in clinical practice to improve the prognosis, diagnostic and therapeutic processes for patients with soft tissue tumors.

METHODS

The Guidelines Development Committee and Systematic Review Committee were composed of a multidisciplinary team of specialists who play an important role in soft tissue tumor care. Clinical questions (CQs) were determined by choosing key decision-making points based on Algorithms for the diagnosis and treatment of soft tissue tumors. The guidelines were developed according to the "Medical Information Network Distribution Service (Minds) Handbook for Clinical Practice Guideline Development 2014" and "Minds Manual for Clinical Practice Guideline Development 2017." Recommendation strength was rated on two levels and the strength of evidence was rated on four levels. The recommendations were decided based on agreement by 70% or more voters.

RESULTS

Twenty-two CQs were chosen by the Guidelines Development Committee. The Systematic Review Committee reviewed the evidence concerning each CQ, a clinical value judgment was added by experts, and the text of each recommendation was determined.

CONCLUSION

We established 22 CQs and recommendations for key decision-making points in the diagnosis and treatment of soft tissue tumors according to the Minds Clinical Practice Guideline development methods. We hope that these guidelines will assist the decision-making of all medical staff engaged in the treatment and diagnosis of soft tissue tumors, and eventually lead to improved soft tissue tumor care in the country.

Association of Race With Receipt of Proton Beam Therapy for Patients With Newly Diagnosed Cancer in the US, 2004-2018

IMPORTANCE

Black patients are less likely than White patients to receive guideline-concordant cancer care in the US. Proton beam therapy (PBT) is a potentially superior technology to photon radiotherapy for tumors with complex anatomy, tumors surrounded by sensitive tissues, and childhood cancers.

OBJECTIVE

To evaluate whether there are racial disparities in the receipt of PBT among Black and White individuals diagnosed with all PBT-eligible cancers in the US.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study evaluated Black and White individuals diagnosed with PBT-eligible cancers between January 1, 2004, and December 31, 2018, in the National Cancer Database, a nationwide hospital-based cancer registry that collects data on radiation treatment, even when it is received outside the reporting facility. American Society of Radiation Oncology model policies were used to classify patients into those for whom PBT is the recommended radiation therapy modality (group 1) and those for whom evidence of PBT efficacy is still under investigation (group 2). Propensity score matching was used to ensure comparability of Black and White patients' clinical characteristics and regional availability of PBT according to the National Academy of Medicine's definition of disparities. Data analysis was performed from October 4, 2021, to February 22, 2022.

EXPOSURE

Patients' self-identified race was ascertained from medical records.

MAIN OUTCOMES AND MEASURES

The main outcome was receipt of PBT, with disparities in this therapy's use evaluated with logistic regression analysis.

RESULTS

Of the 5 225 929 patients who were eligible to receive PBT and included in the study, 13.6% were Black, 86.4% were White, and 54.3% were female. The mean (SD) age at diagnosis was 63.2 (12.4) years. Black patients were less likely to be treated with PBT than their White counterparts (0.3% vs 0.5%; odds ratio [OR], 0.67; 95% CI, 0.64-0.71). Racial disparities were greater for group 1 cancers (0.4% vs 0.8%; OR, 0.49; 95% CI, 0.44-0.55) than group 2 cancers (0.3% vs 0.4%; OR, 0.75; 95% CI, 0.70-0.80). Racial disparities in PBT receipt among group 1 cancers increased over time (annual percent change = 0.09, P < .001) and were greatest in 2018, the most recent year of available data.

CONCLUSIONS AND RELEVANCE

In this cross-sectional study, Black patients were less likely to receive PBT than their White counterparts, and disparities were greatest for cancers for which PBT was the recommended radiation therapy modality. These findings suggest that efforts other than increasing the number of facilities that provide PBT will be needed to eliminate disparities.

Assessment of Proton Beam Therapy Use Among Patients With Newly Diagnosed Cancer in the US, 2004-2018

IMPORTANCE

Proton beam therapy (PBT) is a potentially superior technology to photon radiotherapy for tumors with complex anatomy, those surrounded by sensitive tissues, and childhood cancers.

OBJECTIVE

To assess patterns of use of PBT according to the present American Society of Radiation Oncology (ASTRO) clinical indications in the US.

DESIGN, SETTING, AND PARTICIPANTS

Individuals newly diagnosed with cancer between 2004 and 2018 were selected from the National Cancer Database. Data analysis was performed from October 4, 2021, to February 22, 2022. ASTRO's Model Policies (2017) were used to classify patients into group 1, for which health insurance coverage for PBT treatment is recommended, and group 2, for which coverage is recommended only if additional requirements are met.

MAIN OUTCOMES AND MEASURES

Use of PBT.

RESULTS

Of the 5 919 368 patients eligible to receive PBT included in the study, 3 206 902 were female (54.2%), and mean (SD) age at diagnosis was 62.6 (12.3) years. Use of PBT in the US increased from 0.4% in 2004 to 1.2% in 2018 (annual percent change [APC], 8.12%; P < .001) due to increases in group 1 from 0.4% in 2010 to 2.2% in 2018 (APC, 21.97; P < .001) and increases in group 2 from 0.03% in 2014 to 0.1% in 2018 (APC, 30.57; P < .001). From 2010 to 2018, among patients in group 2, PBT targeted to the breast increased from 0.0% to 0.9% (APC, 51.95%), and PBT targeted to the lung increased from 0.1% to 0.7% (APC, 28.06%) (P < .001 for both). Use of PBT targeted to the prostate decreased from 1.4% in 2011 to 0.8% in 2014 (APC, -16.48%; P = .03) then increased to 1.3% in 2018 (APC, 12.45; P < .001). Most patients in group 1 treated with PBT had private insurance coverage in 2018 (1039 [55.4%]); Medicare was the most common insurance type among those in group 2 (1973 [52.5%]).

CONCLUSIONS AND RELEVANCE

The findings of this study show an increase in the use of PBT in the US between 2004 to 2018; prostate was the only cancer site for which PBT use decreased temporarily between 2011 and 2014, increasing again between 2014 and 2018. These findings may be especially relevant for Medicare radiation oncology coverage policies.

Factors Associated with Acute Toxicity in Pediatric Patients Treated with Proton Radiotherapy: A Report from the Pediatric Proton Consortium Registry

PURPOSE/OBJECTIVES

Limited prospective information regarding acute toxicity in pediatric patients receiving proton therapy (PT) exists. In this study, Pediatric Proton Consortium Registry (PPCR) data was analyzed for factors associated with development of acute toxicity in children receiving passively scattered or pencil beam scanning PT.

MATERIALS/METHODS

Pediatric patients treated with PT and enrolled on the PPCR from 2016-2017 at seven institutions were included. Data was entered on presence versus absence of acute general, cardiac, endocrine, eye, gastrointestinal (GI), genitourinary, hematologic, mouth, musculoskeletal, neurologic, psychologic, respiratory, and skin toxicities prior to (baseline) and at the end of PT (acute). Associations between patient and treatment variables with development of acute toxicity were assessed with multivariable modelling.

RESULTS

Of 422 patients included, PT technique was passively scattered in 241 (57%), pencil beam scanning in 180 (43%), and missing in 1 (<1%) patient. Median age was 9.9 years. Daily anesthesia for treatment was used in 169 (40%). Treatments were categorized as craniospinal irradiation (CSI) (n=100, 24%), focal CNS PT (n=157, 38%), or body PT (n=158, 38%). Passively scattered PT was associated with increased risk of hematologic toxicity compared to pencil beam scanning PT (OR: 3.03, 95% CI: 1.38-6.70, p=0.006). There were no other differences toxicities between PT techniques. Uninsured patients had increased risk of GI (OR: 2.71, 1.12-6.58, p=0.027) and hematologic toxicity (OR: 10.67, 2.68-42.46, p<0.001). Patients receiving concurrent chemotherapy were more likely to experience skin (OR: 2.45, 1.23-4.88, p=0.011), hematologic (OR: 2.87, 1.31-6.25, p=0.008), GI (OR: 2.37, 1.33-4.21, p=0.003), and mouth toxicities (OR: 2.03, 1.10-3.73, p=0.024). Patients receiving 49-55 Gy were more likely to experience skin (OR: 2.18, 1.06-4.44, p=0.033) toxicity than those receiving <49 Gy.

CONCLUSION

The PPCR registry highlights broad differences in acute toxicity rates in children receiving PT, and identifies opportunities for improvements in prevention, monitoring, and treatment of toxicities.

Proton beam therapy with concurrent chemotherapy is feasible in children with newly diagnosed rhabdomyosarcoma

Background

The optimal treatment for rhabdomyosarcoma (RMS) requires multidisciplinary treatment with chemotherapy, surgery, and radiotherapy. Surgery and radiotherapy are integral to the local control (LC) of RMS. However, postsurgical and radiotherapy-related complications could develop according to the local therapy and tumor location. In this study, we conducted a single-center analysis of the outcomes and toxicity of multidisciplinary treatment using proton beam therapy (PBT) for pediatric RMS.

Materials and methods

RMS patients aged younger than 20 years whose RMS was newly diagnosed and who underwent PBT at University of Tsukuba Hospital (UTH) during the period from 2009 to 2019 were enrolled in this study. The patients' clinical information was collected by retrospective medical record review.

Results

Forty-eight patients were included. The 3-year progression-free survival (PFS) and overall survival (OS) rates of all the patients were 68.8% and 94.2%, respectively. The 3-year PFS rates achieved with radical resection, conservative resection, and biopsy only were 65.3%, 83.3%, and 67.6%, respectively (p = 0.721). The 3-year LC rates achieved with radical resection, conservative resection, and biopsy only were 90.9%, 83.3%, and 72.9%, respectively (p = 0.548). Grade 3 or higher mucositis/dermatitis occurred in 14 patients. Although the days of opioid use due to mucositis/dermatitis during the chemotherapy with PBT were longer than those during the chemotherapy without PBT [6.1 and 1.6 (mean), respectively, p = 0.001], the frequencies of fever and elevation of C-reactive protein were equivalent.

Conclusions

Multidisciplinary therapy containing PBT was feasible and provided a relatively fair 3-year PFS, even in children with newly diagnosed RMS without severe toxicity.

A Critical Review of Radiation Therapy: From Particle Beam Therapy (Proton, Carbon, and BNCT) to Beyond

In this paper, we discuss the role of particle therapy—a novel radiation therapy (RT) that has shown rapid progress and widespread use in recent years—in multidisciplinary treatment. Three types of particle therapies are currently used for cancer treatment: proton beam therapy (PBT), carbon-ion beam therapy (CIBT), and boron neutron capture therapy (BNCT). PBT and CIBT have been reported to have excellent therapeutic results owing to the physical characteristics of their Bragg peaks. Variable drug therapies, such as chemotherapy, hormone therapy, and immunotherapy, are combined in various treatment strategies, and treatment effects have been improved. BNCT has a high dose concentration for cancer in terms of nuclear reactions with boron. BNCT is a next-generation RT that can achieve cancer cell-selective therapeutic effects, and its effectiveness strongly depends on the selective ¹⁰B accumulation in cancer cells by concomitant boron preparation. Therefore, drug delivery research, including nanoparticles, is highly desirable. In this review, we introduce both clinical and basic aspects of particle beam therapy from the perspective of multidisciplinary treatment, which is expected to expand further in the future.

New aspects and innovations in the local treatment of renal and urogenital pediatric tumors

Local treatment plays a key role for patients' outcome in tumors of the urogenital tract in children. Despite a great variety of different etiologies, the specific localization of pediatric urogenital tumors renders several characteristic demands to the treating personnel. Surgery and radiotherapy are the main elements of local treatment in this group of neoplasms. Numerous new guidelines and innovative technical developments of surgery and radiotherapy have recently been integrated into treatment concepts for pediatric urogenital tumors. Due to the broadness of the field it is not possible to give a full overview over all aspects. Therefore, this article highlights the most important innovations and new guidelines of surgery and radiotherapy of pediatric urogenital tumors.

Disease Control and Patterns of Failure After Proton Beam Therapy for Rhabdomyosarcoma

PURPOSE

Pediatric patients with rhabdomyosarcoma (RMS) are treated with multimodal therapy, often with radiation therapy (RT) as part of local therapy. We report on the efficacy and patterns of failure after proton beam therapy (PBT) for RMS.

METHODS AND MATERIALS

Between January 2006 and February 2017, patients with RMS were enrolled in a prospective institutional review board-approved registry protocol for pediatric patients undergoing PBT. Demographics, clinical characteristics, and treatment related outcomes were reviewed.

RESULTS

Ninety-four RMS patients were treated with a combination of chemotherapy (CT) and PBT. The majority of patients had head and neck (49%) and genitourinary (30%) primaries. Median tumor size was 4.1 cm (range, 1.0-16.5 cm); 33 patients (35%) had primary tumors >5 cm. Median cyclophosphamide equivalent dose was 14.4 g/m² (range, 0-30.8 g/m²). Median time from CT initiation to RT initiation was 13 weeks (range, 1-58 weeks). With median follow-up of 4 years, 4-year overall survival (OS) was 71%, and 4-year progression-free survival (PFS) was 63%. Thirty patients (32%) experienced relapse (13% with local failure [LF]). Four-year local control (LC) was 85% overall; 4-year LC rates were 100% for low-risk, 85% for intermediate-risk, and 55% for high-risk patients (P = .02). Tumor size predicted LC (P = .007), with 7% versus 33% LF rate by tumor size (≤5 cm vs >5 cm). Delayed RT delivery (≥13 weeks from initiation of CT) predicted worse LC (P = .01). Increased tumor size predicted both inferior PFS (P = .02) and OS (P = .01). Delayed RT delivery predicted both inferior PFS (P = .04) and OS (P = .03).

CONCLUSIONS

PBT provides LC comparable to prior studies using photon RT. Inferior LC, PFS, and OS rates were observed for patients with larger tumors and those treated with delayed RT. This finding supports ongoing prospective efforts to dose-escalate treatment of tumors >5 cm; however, these data call into question the optimal timing of local therapy, particularly for patients treated with reduced-dose cyclophosphamide.

Proton Radiotherapy to Reduce Late Complications in Childhood Head and Neck Cancers

In most childhood head and neck cancers, radiotherapy is an essential component of treatment; however, it can be associated with problematic long-term complications. Proton beam therapy is accepted as a preferred radiation modality in pediatric cancers to minimize the late radiation side effects. Given that childhood cancers are a rare and heterogeneous disease, the support for proton therapy comes from risk modeling and a limited number of cohort series. Here, we discuss the role of proton radiotherapy in pediatric head and neck cancers with a focus on reducing radiation toxicities. First, we compare the efficacy and expected toxicities in proton and photon radiotherapy for childhood cancers. Second, we review the benefit of proton radiotherapy in reducing acute and late radiation toxicities, including risks for secondary cancers, craniofacial development, vision, and cognition. Finally, we review the cost effectiveness for proton radiotherapy in pediatric head and neck cancers. This review highlights the benefits of particle radiotherapy for pediatric head and neck cancers to improve the quality of life in cancer survivors, to reduce radiation morbidities, and to maximize efficient health care use.

Rhabdomyosarcoma

Rhabdomyosarcoma is a heterogeneous disease both in presentation and histology. Improvements in a multimodality therapy resulted in the improved overall survival for patients with a low-risk and intermediate-risk disease but not for patients with a metastatic disease. We reviewed and contrasted the North American and European practice patterns, though ultimately the principles of staging, surgery, radiation therapy, and chemotherapy are similar in both Children's Oncology Group and International Society of Paediatric Oncology treatment approaches. Efforts are underway to investigate improved local control rates in higher risk patients using radiation dose escalation strategies, and delayed primary excision in select cases. The prognostic significance of imaging-based chemotherapy response, proton therapy, novel biomarkers, and targeted drugs will be determined in upcoming clinical trials.

Proton beam therapy for children and adolescents and young adults (AYAs): JASTRO and JSPHO Guidelines

Children and adolescents and young adults (AYAs) with cancer are often treated with a multidisciplinary approach. This includes use of radiotherapy, which is important for local control, but may also cause adverse events in the long term, including second cancer. The risks for limited growth and development, endocrine dysfunction, reduced fertility and second cancer in children and AYAs are reduced by proton beam therapy (PBT), which has a dose distribution that decreases irradiation of normal organs while still targeting the tumor. To define the outcomes and characteristics of PBT in cancer treatment in pediatric and AYA patients, this document was developed by the Japanese Society for Radiation Oncology (JASTRO) and the Japanese Society of Pediatric Hematology/Oncology (JSPHO).

Ewing Sarcoma-Diagnosis, Treatment, Clinical Challenges and Future Perspectives

Ewing sarcoma, a highly aggressive bone and soft-tissue cancer, is considered a prime example of the paradigms of a translocation-positive sarcoma: a genetically rather simple disease with a specific and neomorphic-potential therapeutic target, whose oncogenic role was irrefutably defined decades ago. This is a disease that by definition has micrometastatic disease at diagnosis and a dismal prognosis for patients with macrometastatic or recurrent disease. International collaborations have defined the current standard of care in prospective studies, delivering multiple cycles of systemic therapy combined with local treatment; both are associated with significant morbidity that may result in strong psychological and physical burden for survivors. Nevertheless, the combination of non-directed chemotherapeutics and ever-evolving local modalities nowadays achieve a realistic chance of cure for the majority of patients with Ewing sarcoma. In this review, we focus on the current standard of diagnosis and treatment while attempting to answer some of the most pressing questions in clinical practice. In addition, this review provides scientific answers to clinical phenomena and occasionally defines the resulting translational studies needed to overcome the hurdle of treatment-associated morbidities and, most importantly, non-survival.

Preliminary Experience of Treating Children and Young Adults With Image-Guided Proton Beam Therapy in India

PURPOSE

Proton beam therapy (PBT) has been a preferred modality in pediatric malignancies requiring radiotherapy. We report our preliminary experience of treating consecutive patients younger than 25 years with image-guided pencil beam scanning PBT from the first and only center on the Indian subcontinent.

METHODS

Patients were selected for PBT on the basis of a multidisciplinary tumor board decision. Patient demographic data, as well as tumor and treatment-related characteristics of the cohort, were captured. Patient and treatment-related factors and their association with acute toxicities were analyzed using univariable and multivariable analyses.

RESULTS

Forty-seven patients (27 with CNS and 20 with non-CNS tumors) with a median age of 9 years (range, 2-25 years) were evaluated. Most common diagnoses were ependymoma, rhabdomyosarcoma, and glioma. Seventy-seven percent of patients traveled more than 500 km, and 70% of them lived in metropolitan cities. Forty-nine percent of patients had recurrent disease at presentation, and 15% had received a previous course of radiation. The median dose delivered was 54.8 cobalt gray equivalents (range, 40.0-70.4 cobalt gray equivalents) to a median clinical target volume of 175 mL (range, 18.7-3,083.0 mL), with 34% of patients requiring concurrent chemotherapy (CCT). Acute grade 2 and grade 3 dermatitis, mucositis, and hematologic toxicity was noted in 45% and 2%, 34% and 0%, and 38% and 30% of patients, respectively. Grade 2 fatigue was noted in 26% of patients. On multivariable analysis, for CNS tumors, both CCT and craniospinal irradiation were independently associated with ≥ 2 grade hematologic toxicity, whereas among non-CNS tumors, a clinical target volume > 150 mL was associated with ≥ 2 grade fatigue, head and neck irradiation was associated with ≥ 2 grade mucositis, and CCT was associated with grade ≥ 2 hematologic toxicity.

CONCLUSION

This study demonstrates safe implementation of a PBT program for children and young adults on the Indian subcontinent. Image-guided pencil beam scanning PBT in judiciously selected patients is feasible and can be delivered with acceptable acute toxicities.

Interventional radiotherapy (brachytherapy) achieves very good long-term quality of life in children and adolescents with soft-tissue sarcoma

BACKGROUND

Effective local therapy (surgery, radiation) and systemic multidrug chemotherapy are mandatory for curing childhood sarcoma. The standard radiation therapy for pediatric patients with soft-tissue sarcoma (STS) is external beam radiotherapy (EBRT). Because EBRT may cause long-term side effects with adverse effects on the patients' health and quality of life (QoL), alternative strategies are required. Interventional radiotherapy (IRT; brachytherapy) is established as a standard treatment for several tumors in adulthood. Single-center series have reported low levels of late effects and improved QoL in survivors treated with IRT in childhood. However, IRT is still applied infrequently in pediatric patients.

METHODS

Thirty patients with STS were treated with IRT between 1992 and 2012 at the University Hospital Schleswig Holstein, Germany. Five patients were lost to follow-up, and 25 patients (mean age at time of data collection 24.8 years [range, 10.7-36.1]) could be analyzed focusing on overall survival and QoL (EORTC-C30 questionnaire). For more detailed information regarding general and health-specific questions, a separate questionnaire was developed.

RESULTS

Nineteen of 25 patients were alive 13.4 [1.6-25.2] years after first cancer disease, and the three-year overall survival was 76% (SE, 0.09). The score of QoL/global health status (76.2 [16.6-100]) in our patients outvalues the European (66.1) and equals the German (75.9) reference value.

CONCLUSION

IRT is an effective treatment option for pediatric patients with localized STS. Its role among other radiation dose-sparing techniques such as proton beam therapy has to be defined in prospective studies.

Recent Advances and Challenges in the Treatment of Rhabdomyosarcoma

Rhabdomyosarcoma, the most common soft tissue sarcoma noted in childhood, requires multimodality treatment, including chemotherapy, surgical resection, and/or radiation therapy. The majority of the patients with localized rhabdomyosarcoma can be cured; however, the long-term outcomes in patients with metastatic rhabdomyosarcoma remain poor. The standard chemotherapy regimen for patients with rhabdomyosarcoma is the combination of vincristine, actinomycin, and cyclophosphamide/ifosfamide. In recent clinical trials, modifications of the standard chemotherapy protocol have shown improvements in the outcomes in patients with rhabdomyosarcoma. In various type of malignancies, new treatments, such as molecular targeted drugs and immunotherapies, have shown superior clinical outcomes compared to those of standard treatments. Therefore, it is necessary to assess the benefits of these treatments in patients with rhabdomyosarcoma. Moreover, recent basic and clinical studies on rhabdomyosarcoma have reported promising therapeutic targets and novel therapeutic approaches. This article reviews the recent challenges and advances in the management of rhabdomyosarcoma.

Early Experience of the First Single-Room Gantry Mounted Active Scanning Proton Therapy System at an Integrated Cancer Center

Introduction: Review the early experience with a single-room gantry mounted active scanning proton therapy system.

Material and Methods: All patients treated with proton beam radiotherapy (PBT) were enrolled in an institutional review board-approved patient registry. Proton beam radiotherapy was delivered with a 250 MeV gantry mounted synchrocyclotron in a single-room integrated facility within the pre-existing cancer center. Demographic data, cancer diagnoses, treatment technique, and geographic patterns were obtained for all patients. Treatment plans were evaluated for mixed modality therapy. Insurance approval data was collected for all patients treated with PBT.

Results: A total of 132 patients were treated with PBT between March 2018 and June 2019. The most common oncologic subsites treated included the central nervous system (22%), gastrointestinal tract (20%), and genitourinary tract (20%). The most common histologies treated included prostate adenocarcinoma (19%), non-small cell lung cancer (10%), primary CNS gliomas (8%), and esophageal cancer (8%). Rationale for PBT treatment included limitation of dose to adjacent critical organs at risk (67%), reirradiation (19%), and patient comorbidities (11%). Patients received at least one x-ray fraction delivered as prescribed (36%) or less commonly due to unplanned machine downtime (34%). Concurrent systemic therapy was administered to 57 patients (43%). Twenty-six patients (20%) were initially denied insurance coverage and required peer-to-peers (65%), written appeals (12%), secondary insurance approval (12%), and comparison x-ray to proton plans (8%) for subsequent approval. Proton beam radiotherapy approval required a median of 17 days from insurance submission.

Discussion: Incorporation of PBT into our existing cancer center allowed for multidisciplinary oncologic treatment of a diverse population of patients. Insurance coverage for PBT presents as a significant hurdle and improvements are needed to provide more timely access to necessary oncologic care.

Do children and adolescents with completely resected alveolar rhabdomyosarcoma require adjuvant radiation? A report from the Children's Oncology Group

BACKGROUND

The role of adjuvant radiotherapy (RT) remains unclear in patients with localized, completely resected (group I) alveolar rhabdomyosarcoma (ARMS).

PROCEDURE

Patients with group I ARMS enrolled on any one of three prior Children's Oncology Group (COG) clinical trials (D9602, D9803, or ARST0531) were analyzed. All patients received systemic chemotherapy and 36 Gy adjuvant RT (if given) to the primary site at week 12 or week 4 for D9602/D9803 and ARST0531, respectively.

RESULTS

Thirty-six patients with group I ARMS were treated on D9602 (n = 6), D9803 (n = 17), or ARST0531 (n = 13), of whom 24 (67%) were male. The median age was 4.1 years (range, 0.8-45.8). Twenty (56%) patients had an unfavorable primary site, and 10 (28%) had tumors > 5 cm. FOXO1-fusion status was negative, positive, and unknown in 10 (28%), 15 (42%), and 11 (30%) tumors, respectively. Twenty-two (61%) patients received RT. Overall, the four-year event-free survival (EFS) and overall survival (OS) were 70.8% and 88.3%, respectively. Patients with FOXO1 positivity who received RT had superior EFS compared with those who did not (77.8% vs 16.7%; P = 0.03). Among 10 patients who were FOXO1 negative, the outcome was similar with or without RT.

CONCLUSIONS

Although limited by a small sample size, data from this study support the routine use of adjuvant RT in patients with FOXO1-positive disease even after complete resection. Additionally, omitting adjuvant RT is rational for patients with FOXO1-negative ARMS and will be prospectively investigated in the current COG trial ARST1431.

The survival benefit of radiotherapy in localized primary adult rhabdomyosarcoma

AIM

To evaluate the role of radiotherapy (RT) in the treatment of localized primary adult rhabdomyosarcoma (RMS).

METHODS

This retrospective study identified 62 consecutive adult patients with localized primary RMS from January 2000 and July 2016. Local failure-free survival (LFFS), distant metastasis-free survival (DMFS) and overall survival (OS) were analyzed by the Kaplan-Meier method. Multivariate Cox proportional hazards regression models were fit to assess the ability of patient characteristics to predict survival.

RESULTS

With a median follow-up of 33 months (range, 6-195 months), the 5-year LFFS, DMFS and OS of all patients were 64.0%, 50.0% and 45.0%, respectively. RT was administered to 28 patients (45.2%). Patients who received RT had a higher 5-year LFFS (81.7% vs 47.2%), 5-year DMFS (59.4% vs 43.1%) and 5-year OS (57.1% vs 34.8%) compared with patients who did not received RT. In mulitvariate analysis, RT retained significance as an independent predictor of improved LFFS [hazard ratio (HR) = 0.282; 95% confidence interval (CI), 0.095-0.838; P = 0.023], DMFS (HR = 0.289; 95% CI, 0.125-0.991; P = 0.004) and OS (HR = 0.334; 95% CI, 0.153-0.727; P = 0.006).

CONCLUSIONS

RT significantly reduced local recurrence, distant metastasis and tumor mortality compared with no radiotherapy for localized primary adult RMS.

Efficacy and Safety of Limited-Margin Conformal Radiation Therapy for Pediatric Rhabdomyosarcoma: Long-Term Results of a Phase 2 Study

PURPOSE

Our purpose was to assess disease outcomes and late toxicities in pediatric patients with rhabdomyosarcoma treated with conformal photon radiation therapy (RT).

METHODS AND MATERIALS

Sixty-eight patients (median age, 6.9 years) were treated with conformal photon RT to the primary site on a prospective clinical trial. Target volumes included a 1-cm expansion encompassing microscopic disease. Prescribed doses were 36 Gy to this target volume and 50.4 Gy to gross residual disease. Chemotherapy consisted of vincristine/dactinomycin (n = 6), vincristine/dactinomycin/cyclophosphamide (n = 37), or vincristine/dactinomycin/cyclophosphamide-based combinations (n = 25). Patients were evaluated with primary-site magnetic resonance imaging, whole-body [¹⁸F]fluorodeoxyglucose positron emission tomography, and chest computed tomography for 5 years after treatment.

RESULTS

Five-year disease-free survival was 88% for low-risk (n = 8), 76% for intermediate-risk (n = 37), and 36% for high-risk (n = 23) patients (P ≤ .01 for low risk/intermediate risk vs high risk). The cumulative incidence of local failure (LF) at 5 years for the entire cohort was 10.4%. Tumor size at diagnosis was a significant predictor of LF (P < .01). Patients with head and neck primary tumors (n = 31) had a 35% cumulative incidence of cataracts; the risk correlated with lens dose (P = .0025). Jaw dysfunction was more severe when the pterygoid and masseter muscles received a mean dose of >20 Gy (P = .013). Orbital hypoplasia developed more frequently after a mean bony orbit dose of >30 Gy (P = .041). Late toxicity in patients with genitourinary tumors included microscopic hematuria (9 of 14), bladder-wall thickening (10 of 14), and vaginal stenosis (2 of 5).

CONCLUSIONS

Long-term LF rates were low, and higher rates correlated with larger tumors. Treatment-related toxicities resulting in measurable functional deficits were not infrequent, despite the conformal RT approach.

Patterns of failure and toxicity profile following proton beam therapy for pediatric bladder and prostate rhabdomyosarcoma

PURPOSE/OBJECTIVE(S)

Bladder and prostate are unfavorable sites for rhabdomyosarcoma (B/P-RMS), and represent a challenging location for radiotherapy.

MATERIALS/METHODS

Nineteen patients with B/P-RMS were enrolled on a prospective registry protocol (2008-2017) and treated with chemotherapy, proton beam therapy (PBT), and surgical resection (n = 8; 42%). Emphasis was given to treatment technique, disease-related outcomes, and toxicity associated with PBT.

RESULTS

The majority of patients had bladder RMS (74%) of embryonal histology (95%), Group III (68%), and intermediate-risk disease by Children's Oncology Group (COG) risk stratification (89%). Seven patients (37%) had primary tumors >5 cm in size. All patients were treated according to COG protocols. With a median follow-up of 66.2 months, 5-year overall survival (OS) and progression-free survival (PFS) were 76%. Four patients (21%) experienced disease relapse, all presenting with local failure. The 5-year local control (LC) rate was 76%. Tumor size predicted LC, with 5-year LC for patients with >5 cm tumors being 43% versus 100% for those with ≤5 cm tumors (P = .006). Univariate analysis demonstrated an effect of tumor size on OS (tumor >5 cm, hazard ratio [HR] 17.7, P = .049) and PFS (HR 17.7, P = .049). Acute grade 2 toxicity was observed in two patients (11%, transient proctitis). Late grade 2+ toxicity was observed in three patients (16%; n = 1 grade 2 skeletal deformity; n = 3 transient grade 2 urinary incontinence; one patient experienced both).

CONCLUSIONS

PBT for B/P-RMS affords promising disease-related outcomes with an acceptable toxicity profile. Higher local failure rates were observed for larger tumors, supporting dose-escalation components of ongoing RMS clinical trials.

Pediatric Cancer

In pediatric brain tumors, the intensification of chemotherapy has allowed for a reduction in radiotherapy (RT) volume to an involved field approach, particularly in patients with medulloblastoma. For patients with low-grade gliomas, the trend has remained to delay RT with chemotherapy; however, when RT is used, typically smaller clinical target volume margins are used. For patients with extracranial tumors, intensive chemotherapy to address systemic disease with local control is considered standard. Proton beam therapy shows significant promise in addressing both short-term and long-term toxicities in both central nervous system (CNS) and non-CNS pediatric tumors.

Paediatric proton therapy

Proton beam therapy is a highly conformal form of radiation therapy, which currently represents an important therapeutic component in multidisciplinary management in paediatric oncology. The precise adjustability of protons results in a reduction of radiation-related long-term side-effects and secondary malignancy induction, which is of particular importance for the quality of life. Proton irradiation has been shown to offer significant advantages over conventional photon-based radiotherapy, although the biological effectiveness of both irradiation modalities is comparable. This review evaluates current data from clinical and dosimetric studies on the treatment of tumours of the central nervous system, soft tissue and bone sarcomas of the head and neck region, paraspinal or pelvic region, and retinoblastoma. To date, the clinical results of irradiating childhood tumours with high-precision proton therapy are promising both with regard to tumour cure and the reduction of adverse events. Modern proton therapy techniques such as pencil beam scanning and intensity modulation are increasingly established modern facilities. However, further investigations with larger patient cohorts and longer follow-up periods are required, in order to be able to have clear evidence on clinical benefits.

Increased local failure for patients with intermediate-risk rhabdomyosarcoma on ARST0531: A report from the Children's Oncology Group

BACKGROUND

The objective of this study was to evaluate local control for patients with intermediate-risk rhabdomyosarcoma (RMS) treated on Children's Oncology Group (COG) protocol ARST0531.

METHODS

This study analyzed 424 patients with intermediate-risk RMS. Patients were randomized to chemotherapy with either vincristine, dactinomycin, and cyclophosphamide (VAC) or VAC alternating with vincristine and irinotecan. With the goal of improving local control, radiation therapy (RT) was delivered early at week 4 and was concurrent with irinotecan in the experimental arm. Individualized local control plans for children 24 months old or younger were allowed. Local failure on ARST0531 was compared with local failure on the preceding COG intermediate-risk study, D9803.

RESULTS

For patients with group I/II alveolar RMS (n = 55), the 5-year cumulative incidence of local failure was 13.4%; for group III alveolar RMS (n = 141), it was 20.2%; and for group III embryonal RMS (n = 228), it was 27.9% (P = .03). Among patients with group III disease, local failure did not differ by histology, site, nodal status, RT modality, or treatment arm. Local failure was worse for a tumor size >5 cm (32.3% vs 16.7%; P = .001). Among patients with group III embryonal RMS, local failure was higher on ARST0531 than D9803 (27.9% vs 19.4%; P = .03). After the exclusion of patients 24 months old or younger or patients who did not receive radiation, local failure remained significantly increased on ARST0531 (P = .02). After adjustments for clinical prognostic factors, event-free survival and overall survival were worse on ARST0531 (P = .004 and P = .05, respectively).

CONCLUSIONS

Despite interventions designed to enhance local control, local control was inferior on ARST0531 in comparison with D9803. The reason for this is unclear, but it could be the reduced cyclophosphamide dose on ARST0531.

Worse Outcomes for Head and Neck Rhabdomyosarcoma Secondary to Reduced-Dose Cyclophosphamide

PURPOSE

Recent trends, including the use of proton therapy and administration of reduced doses of cyclophosphamide, have been adapted in head and neck (HN) rhabdomyosarcoma (RMS) to reduce late morbidity. Our primary goal was to analyze local control and survival outcomes after photon versus proton irradiation in pediatric patients with HN-RMS, with the secondary goal of analyzing the effect of cyclophosphamide dose on disease outcomes.

METHODS AND MATERIALS

This single-institution cohort study comprised 76 pediatric HN-RMS patients treated with definitive chemoradiation from 2000 to 2018. Fifty-one patients (67%) received intensity modulated photon radiation therapy, and 25 (33%) received proton therapy.

RESULTS

Local failure (LF) at 2 years was 12.5% for parameningeal RMS and 0% for orbital RMS and other head and neck sites (P = .24). Patients treated with protons were more likely to have received reduced-dose cyclophosphamide (P < .0001). The 2-year LF was 7.9% in the intensity modulated photon radiation therapy cohort versus 14.6% in the proton cohort (P = .07), with no difference in survival outcomes. Cumulative cyclophosphamide dose was significantly associated with 2-year LF: 0% for cumulative dose of >20 g/m2 versus 15.3% for ≤20 g/m2 (P = .04). In parameningeal RMS patients (n = 59), both cumulative cyclophosphamide dose and dose intensity were associated with LF (P = .01). There was a trend toward worse event-free survival for parameningeal RMS patients who received reduced-dose-intensity cyclophosphamide (59.2% vs 70.6%, P = .11).

CONCLUSIONS

Both dose-intensity and cumulative cyclophosphamide dose seem to play an important role in achieving local control for HN-RMS patients treated with either protons or photons. Longer follow-up is needed to further assess disease outcomes with proton therapy.

Patterns of failure following proton beam therapy for head and neck rhabdomyosarcoma

PURPOSE

Pediatric patients with rhabdomyosarcoma (RMS) of the head and neck (H&N) are treated with multimodal therapy, often with radiotherapy (RT) as definitive local therapy. We report on the patterns of failure following proton beam therapy (PBT) for H&N RMS.

METHODS

Forty-six H&N RMS patients were enrolled on a prospective registry protocol between 2006 and 2015. All were treated with a combination of chemotherapy (ChT) and PBT. Most patients (25 patients, 54%) had parameningeal tumors, of which 11 (24%) had intracranial extension (ICE). Thirteen patients (28%) had primary tumors greater than 5 cm. Median total cyclophosphamide (CPM) equivalent dose was 13.2 g/m² (range 0-16.8 g/m²). Median RT dose was 50.4 Gy(RBE) (range 36 Gy[RBE]-50.8 Gy[RBE]).

RESULTS

With median follow-up of 3.9 years, five-year overall survival was 76%, and five-year progression-free survival was 57%. Seventeen patients (37%) experienced relapse, including 7 with local failure (LF). Five-year local control (LC) was 84%. Tumor size greater than 5 cm predicted increased risk of LF (hazard ratio [HR] 6.49, p = 0.03), as did the presence of ICE at diagnosis (HR 5.21, p = 0.03). Six relapses occurred in patients with ICE; all included a component of central nervous system relapse, with leptomeningeal disease and/or LF with an intracranial component. Delayed RT delivery after week 4 of ChT predicted increased risk of relapse for ICE patients (HR 10.49, p = 0.006).

CONCLUSIONS

PBT confers excellent LC, and a favorable late toxicity profile as compared with prior photon RT data. Our observations support ongoing trial efforts to dose-escalate RT for patients with larger tumors. However, these data raise concerns regarding excess failures among patients with ICE.

Proton beam therapy in pediatric oncology

PURPOSE OF REVIEW

The advent of proton beam therapy (PBT) has initiated a paradigm shift in the field of pediatric radiation oncology, with increasing promise to alleviate both short-term and long-term toxicities. Given the dramatic rise in proton therapy centers in the United States, a discussion of the quality of evidence supporting its use in pediatric cancers is warranted.

RECENT FINDINGS

Proton radiotherapy appears to decrease the incidence and severity of late effects with the strongest evidence in pediatric brain tumor cohorts that shows benefits in neurocognitive, hearing, and endocrine outcomes. However, emerging data has shown that more conservative brainstem dose limits with protons compared with photons are required to limit brainstem toxicity; these modified recommendations have been incorporated into national cooperative group studies. Decreased toxicity in tumors outside of the CNS for PBT have also been reported in sarcomas, Hodgkin disease and neuroblastoma. Similarly, QoL outcomes are improved in brain tumor and other cohorts of patients treated with PBT.

SUMMARY

The collective findings demonstrate improved understanding and refinement of PBT in pediatric cancers. Data on QOL, toxicity and disease outcomes with PBT should continue to be collected and reported in order to understand the full extent of the risks and benefits associated with PBT.

Evolving Radiotherapy Techniques in Paediatric Oncology

AIMS

Childhood cancer is rare and survival of childhood cancer has increased up to 80% at 5 years after diagnosis. Radiotherapy is an important element of the multimodal treatment concept. However, due to growing tissue, children are particularly sensitive to radiation-related side-effects and the induction of secondary malignancies. However, radiotherapy techniques have continuously progressed. In addition, modern treatment concepts have been improved in order to minimise long-term effects. Today, radiotherapy is used for various tumour types in childhood, such as sarcomas and tumours of the central nervous system.

MATERIALS AND METHODS

External beam therapy with either photons or protons and brachytherapy are predominantly used for the treatment of childhood tumours. Technical developments and features, as well as clinical outcomes, for several tumour entities are presented.

RESULTS

The development of radiotherapy techniques, as well as risk-adapted therapy concepts, resulted in promising outcome regarding tumour control, survival and therapy-related side-effects. It is assumed that proton therapy will be increasingly used for treating children in the future. However, more data have to be collected through multi-institutional registries in order to strengthen the evidence.

CONCLUSION

The development of radiotherapy techniques is beneficial for children in terms of reducing dose exposure. As compared with other modern and highly conformal techniques, particularly proton therapy may achieve high survival rates and tumour control rates while decreasing the risk for side-effects. However, clinical evidence for modern radiotherapy techniques is still limited today. An optimal patient triaging with the selection of the most appropriate radiation technique for each individual patient will be an important goal for the future.

Risk of second cancer after ion beam radiotherapy: insights from animal carcinogenesis studies

Purpose: To review recent studies to better understand the risk of second cancer after ion beam radiotherapy and to clarify the importance of animal radiobiology therein. Results: Risk of developing second cancer after radiotherapy is a concern, particularly for survivors of childhood tumors. Ion beam radiotherapy is expected to reduce the risk of second cancer by reducing exposure of normal tissues to radiation. Large uncertainty lies, however, in the choice of relative biological effectiveness (RBE) of high linear energy transfer (LET) radiation (e.g. carbon ions and neutrons) in cancer induction, especially for children. Studies have attempted to predict the risk of second cancer after ion beam radiotherapy based on an assessment of radiation dose, the risk of low LET radiation, and assumptions about RBE. Animal experiments have yielded RBE values for selected tissues, radiation types, and age at the time of irradiation; the results indicate potentially variable RBE which depends on tissues, ages, and dose levels. Animal studies have also attempted to identify genetic alterations in tumors induced by high LET radiation. Conclusions: Estimating the RBE value for cancer induction is important for understanding the risk of second cancer after ion beam radiotherapy. More comprehensive animal radiobiology studies are needed.

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.

Radiotherapy Advances in Pediatric Neuro-Oncology

Radiation therapy (RT) represents an integral component in the treatment of many pediatric brain tumors. Multiple advances have emerged within pediatric radiation oncology that aim to optimize the therapeutic ratio—improving disease control while limiting RT-related toxicity. These include innovations in treatment planning with magnetic resonance imaging (MRI) simulation, as well as increasingly sophisticated radiation delivery techniques. Advanced RT techniques, including photon-based RT such as intensity-modulated RT (IMRT) and volumetric-modulated arc therapy (VMAT), as well as particle beam therapy and stereotactic RT, have afforded an array of options to dramatically reduce radiation exposure of uninvolved normal tissues while treating target volumes. Along with advances in image guidance of radiation treatments, novel RT approaches are being implemented in ongoing and future prospective clinical trials. As the era of molecular risk stratification unfolds, personalization of radiation dose, target, and technique holds the promise to meaningfully improve outcomes for pediatric neuro-oncology patients.