Outcomes and patterns of care in a nationwide cohort of pediatric medulloblastoma: Factors affecting proton therapy utilization

Assessing Equity of Access to Proton Beam Therapy: A Literature Review

Proton beam therapy (PBT) is one of the most advanced radiotherapy technologies, with growing evidence to support its use in specific clinical scenarios and exponential growth of demand and capacity worldwide over the past few decades. However, geographical inequalities persist in the distribution of PBT centres, which translate into variations in access and use of this technology. The aim of this work was to look at the factors that contribute to these inequalities, to help raise awareness among stakeholders, governments and policy makers. A literature search was conducted using the Population, Intervention, Comparison, Outcomes (PICO) criteria. The same search strategy was run in Embase and Medline and identified 242 records, which were screened for manual review. Of these, 24 were deemed relevant and were included in this analysis. Most of the 24 publications included in this review originated from the USA (22/24) and involved paediatric patients, teenagers and young adults (61% for children and/or teenagers and young adults versus 39% for adults). The most reported indicator of disparity was socioeconomic status (16/24), followed by geographical location (13/24). All the studies evaluated in this review showed disparities in the access to PBT. As paediatric patients make up a significant proportion of the PBT-eligible patients, equity of access to PBT also raises ethical considerations. Therefore, further research is needed into the equity of access to PBT to reduce the care gap.

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.

Non-inferiority of fragmented care for high-risk pediatric neuroblastoma patients: a single institution analysis

Pediatric neuroblastoma (NB) patients receive multi-modal therapy and may experience care fragmented among multiple institutions with a significant travel burden, which has been associated with poor outcomes for some adult cancers. We hypothesized that fragmented care for pediatric NB patients is associated with inferior outcomes compared to treatment consolidated at one location. We reviewed paper and electronic records for pediatric NB patients who received ≥1 hematopoietic stem cell transplant (HSCT) at Duke from 1990-2017. Fragmented care was defined by treatment at >1 institution and grouped by 2 institutions vs. 3+ institutions. Distances were calculated using Google Maps. To compare all care groups, we used Fisher's Exact and Kruskal-Wallis tests for demographic and treatment characteristics, Kaplan-Meier for unadjusted overall survival (OS), and Cox proportional hazards for factors associated with OS. Of 127 eligible patients, 102 (80.3%) patients experienced fragmented care, with 17 treated at 3+ facilities. Kaplan-Meier analysis did not associate fragmented care with increased mortality (log-rank p = 0.13). With multivariate analysis, only earlier diagnostic decade and greater distance to HSCT remained significantly associated with worsened OS. In this single institutional study, we found fragmented care did not impact overall survival. Worsened overall survival was associated with increased travel distance for HSCT and further research should aim to improve supportive processes for patients undergoing HSCT for high-risk neuroblastoma.

Examining the Effect of Travel Distance to Pediatric Cancer Centers and Rurality on Survival and Treatment Experiences: A Systematic Review

Accessing pediatric cancer treatment remains problematic for rural families or those living at increased distances from specialized centers. Rural adult cancer patients or those living far removed from treatment may present with later stage disease, receive different treatments than their closer counterparts, and experience worsened survival. While the financial and psychosocial strain of increased travel is well documented, effects of travel distance on similar outcomes for pediatric cancer patients remain ill-defined. We conducted a systematic review to synthesize literature examining the effect of travel distance and/or rurality (as a proxy for distance) on pediatric cancer treatment experiences and survival outcomes. Included studies examined travel distance to specialized centers or rural status for patients above 21 years of age. Studies were excluded if they focused on financial or quality of life outcomes. We analyzed 24 studies covering myriad malignancies and outcomes, including location of care, clinical trial participation, and likelihood of receiving specialized treatments such as stem cell transplants or proton beam therapy. Most were retrospective, and 9 were conducted outside the United States. While some studies suggest rural patients may experience worsened survival and those traveling furthest may experience shorter hospitalization times/rates, the available evidence does not uniformly assert negative effects of increased distance.

Cost-Effectiveness Models of Proton Therapy for Head and Neck: Evaluating Quality and Methods to Date

PURPOSE

Proton beam therapy (PBT) is associated with less toxicity relative to conventional photon radiotherapy for head-and-neck cancer (HNC). Upfront delivery costs are greater, but PBT can provide superior long-term value by minimizing treatment-related complications. Cost-effectiveness models (CEMs) estimate the relative value of novel technologies (such as PBT) as compared with the established standard of care. However, the uncertainties of CEMs can limit interpretation and applicability. This review serves to (1) assess the methodology and quality of pertinent CEMs in the existing literature, (2) evaluate their suitability for guiding clinical and economic strategies, and (3) discuss areas for improvement among future analyses.

MATERIALS AND METHODS

PubMed was queried for CEMs specific to PBT for HNC. General characteristics, modeling information, and methodological approaches were extracted for each identified study. Reporting quality was assessed via the Consolidated Health Economic Evaluation Reporting Standards 24-item checklist, whereas methodologic quality was evaluated via the Philips checklist. The Cooper evidence hierarchy scale was employed to analyze parameter inputs referenced within each model.

RESULTS

At the time of study, only 4 formal CEMs specific to PBT for HNC had been published (2005, 2013, 2018, 2020). The parameter inputs among these various Markov cohort models generally referenced older literature, excluding many clinically relevant complications and applying numerous hypothetical assumptions for toxicity states, incorporating inputs from theoretical complication-probability models because of limited availability of direct clinical evidence. Case numbers among study cohorts were low, and the structural design of some models inadequately reflected the natural history of HNC. Furthermore, cost inputs were incomplete and referenced historic figures.

CONCLUSION

Contemporary CEMs are needed to incorporate modern estimates for toxicity risks and costs associated with PBT delivery, to provide a more accurate estimate of value, and to improve their clinical applicability with respect to PBT for HNC.

Racial and ethnic disparities in survival of children with brain and central nervous tumors in the United States

BACKGROUND

Despite improvements in overall survival for pediatric cancers, treatment disparities remain for racial/ethnic minorities compared to non-Hispanic Whites; however, the impact of race on treatment outcomes for pediatric brain and central nervous system (CNS) tumors in the United States is not well known.

METHODS

We included 8713 children aged 0-19 years with newly diagnosed primary brain and CNS tumors between 2000 and 2015 from the Census Tract-level SES and Rurality Database developed by Surveillance, Epidemiology, and End Results (SEER) Program. We used chi-square tests to assess differences in sociodemographic, cancer, and treatment characteristics by race/ethnicity and Kaplan-Meier curves and Cox proportional hazards models to examine differences in 10-year survival, adjusting for these characteristics.

RESULTS

Among 8713 patients, 56.75% were non-Hispanic White, 9.59% non-Hispanic Black, 25.46% Hispanic, and 8.19% from "other" racial/ethnic groups. Median unadjusted survival for all pediatric brain tumors was 53 months, but varied significantly by race/ethnicity with a median survival of 62 months for non-Hispanic Whites, 41 months for non-Hispanic Blacks, and 40 months for Hispanic and other. Multivariable analyses demonstrated minority racial groups still had significantly higher hazard of death than non-Hispanic Whites; Hispanic (adjusted hazard ratio [aHR] 1.25 [1.18-1.31]); non-Hispanic Black (aHR 1.12 [1.04-1.21]); other (aHR 1.22 [1.12-1.32]). Results were consistent when stratified by tumor histology.

CONCLUSION

We identified disparities in survival among racial/ethnic minorities with pediatric brain and CNS tumors, with Hispanic patients having the highest risk of mortality. Eliminating these disparities requires commitment toward promoting heath equity and personalized cancer treatment.

Design and commissioning of an image-guided small animal radiation platform and quality assurance protocol for integrated proton and x-ray radiobiology research

Small animal x-ray irradiation platforms are expanding the capabilities and future pathways for radiobiology research. Meanwhile, proton radiotherapy is transitioning to a standard treatment modality in the clinician’s precision radiotherapy toolbox, highlighting a gap between state-of-the-art clinical radiotherapy and small animal radiobiology research. Comparative research of the biological differences between proton and x-ray beams could benefit from an integrated small animal irradiation system for in vivo experiments and corresponding quality assurance (QA) protocols to ensure rigor and reproducibility. The objective of this study is to incorporate a proton beam into a small animal radiotherapy platform while implementing QA modelled after clinical protocols.

A 225 kV x-ray small animal radiation research platform (SARRP) was installed on rails to align with a modified proton experimental beamline from a 230 MeV cyclotron-based clinical system. Collimated spread out Bragg peaks (SOBP) were produced with beam parameters compatible with small animal irradiation. Proton beam characteristics were measured and alignment reproducibility with the x-ray system isocenter was evaluated. A QA protocol was designed to ensure consistent proton beam quality and alignment. As a preliminary study, cellular damage via γ-H2AX immunofluorescence staining in an irradiated mouse tumor model was used to verify the beam range in vivo.

The beam line was commissioned to deliver Bragg peaks with range 4–30 mm in water at 2 Gy min⁻¹. SOBPs were delivered with width up to 25 mm. Proton beam alignment with the x-ray system agreed within 0.5 mm. A QA phantom was created to ensure reproducible alignment of the platform and verify beam delivery. γ-H2AX staining verified expected proton range in vivo.

An image-guided small animal proton/x-ray research system was developed to enable in vivo investigations of radiobiological effects of proton beams, comparative studies between proton and x-ray beams, and investigations into novel proton treatment methods.

Salvage Therapy for Childhood Medulloblastoma: A Single Center Experience

INTRODUCTION

Children diagnosed with medulloblastoma (MB) who are refractory to upfront therapy or experience recurrence have very poor prognoses. Although phase I and phase II trials exist, these treatments bear significant treatment-related morbidity and mortality.

METHODS

A retrospective review of children diagnosed with a recurrence of MB from 2002 to 2015 at McMaster University was undertaken.

RESULTS

Recurrent disease in 10 patients involved leptomeningeal dissemination, with 3 experiencing local recurrence. In three recurrent patients the disease significantly progressed, and the children were palliated. The remaining 10 children underwent some form of salvage therapy, including surgical re-resection, radiation, and chemotherapy, either in isolation or in varying combinations. Of the 13 children experiencing treatment-refractory or recurrent disease, 4 are currently alive with a median follow-up of 38.5 months (75.5 months). Of the eight patients with molecular subgrouping data, none of the Wnt MB experienced recurrence.

CONCLUSION

Recurrent MB carried a poor prognosis with a 5-year overall survival (OS) of 18.2% despite the administration of salvage therapy. The upfront therapy received, available treatment, and tolerability of the proposed salvage therapy resulted in significant heterogeneity in the treatment of our recurrent cohort.

National practice patterns of proton versus photon therapy in the treatment of adult patients with primary brain tumors in the United States

OBJECTIVES

To examine patterns of care associated with the administration of proton versus photon therapy for adult patients with primary brain tumors in a large national cohort from the United States.

METHODS

The National Cancer Database (NCDB) was queried for newly diagnosed primary brain tumors (2004-2014) in adult patients aged 18 and older receiving proton or photon radiotherapy. Clinical features, patient demographics and treatment parameters were extracted. Differences between groups were assessed using multivariable logistic regression analysis.

RESULTS

In total, 73,073 patients were analyzed (n = 72,635 [99.4%] photon therapy, n = 438 [0.6%] proton therapy). On multivariable analysis of photon versus proton therapy, several factors predicted for receipt of proton therapy, including younger age (p = .041), highest income quartile (p = .007), treatment at academic institutions (p < .001), in regional facilities outside the Midwest/South (p < .001), diagnosis in more recent years (p = .003), fewer comorbidities (p < .001) and non-glioblastoma histology (p < .001).

CONCLUSIONS

There are several significant socioeconomic variables that influence receipt of proton therapy for primary brain tumors. Although not implying causation, the socioeconomic findings discovered herein should be taken into account when delivering cancer care to all patients.