Radiotherapy Utilization and Outcomes on a Contemporary Trial for Pediatric High-Risk Hodgkin Lymphoma Study

PURPOSE/OBJECTIVE(S)

Contemporary trials in pediatric Hodgkin lymphoma (cHL) evaluate strategies to reduce radiotherapy (RT) utilization while maintaining excellent progression-free survival (PFS). An alternative strategy is to irradiate selective sites at higher risk of relapse, and/or use proton therapy (PT) to minimize exposure to healthy tissue. We investigated the use of PT and photon therapy (XRT) and associated early outcomes among patients receiving involved site RT (ISRT) to high-risk sites on the Children's Oncology Group (COG) trial AHOD1331 (NCT021664643).

MATERIALS/METHODS

This multicenter randomized, open-label phase 3 study enrolled patients 2-21 years (yrs) with previously untreated cHL: stages IIB + bulk, IIIB, IVA, IVB. Patients were randomized to 5 cycles of either ABVE-PC (doxorubicin, bleomycin, vincristine, etoposide, prednisone, cyclophosphamide) or the brentuximab vedotin (BV) containing regimen BV-AVE-PC given every 21 days. ISRT to 21 Gy was given to bulky mediastinal adenopathy and slow responding lesions (SRL) defined by 5-point score 4 or 5 on PET-CT after 2 cycles. ISRT could be delivered as 3D conformal XRT (3D), intensity modulated XRT (IMRT), or proton therapy (PT). Utilization of RT was compared by mode and by study enrollment midpoint among irradiated patients. Severe acute toxicity assessment included any incident grade 3 or higher toxicity during the ISRT period, except for neuropathy.

RESULTS

Among 587 eligible patients who were enrolled across 153 institutions between March 2015 and August 2019 with a median follow up of 43.1 months, the 3-yr PFS was 82.5% (90% CI, 78.3%-85.9%) with ABVE-PC and 92.5% (90% CI 89.5%-94.6%) with BV-AVE-PC (p = 0.0002). There was no difference in ISRT receipt or modality by study arm (p = 0.33). Among those who received RT 69.7% received it due to bulky mediastinal adenopathy, 6.6% due to SRL, and 23.7% for both. Overall, 317 (54.0%) patients received protocol RT of which 28.7% received 3D, 44.8% received IMRT, and 26.5% received PT. PT utilization increased over the course of the study from 21.5% among the first 50% of irradiated patients to 31.5% in the second half of irradiated patients (p = 0.045). The 3-yr progression-free survival rates overall by RT were comparable: PT (88.0%, 90% CI 80.6% - 92.7%%); XRT (87.1%, 90% CI 82.9%-90.4%) (p = 0.85). No difference in PFS was observed between 3D versus IMRT (p = 0.65). No differences were observed in severe acute toxicities (8.33% vs. 8.15%, p = 0.96) between PT and XRT.

CONCLUSION

Selective use of RT results in excellent outcomes for pediatric patients with high-risk HL and combination chemotherapy inclusive of the novel agent BV. Over the course of the study, PT utilization increased as an RT modality. Early results suggest that PT does not compromise disease control and has similar acute toxicity as XRT. Long term follow-up (>10 years) is needed to evaluate for secondary malignancies and cardiac toxicity among the different RT modalities.

Pediatric Esthesioneuroblastoma Treated with Proton Radiotherapy

PURPOSE/OBJECTIVE(S)

Given its tendency to abut and infiltrate critical skull base anatomy, pediatric esthesioneuroblastoma (EN) presents a local control challenge, particularly given the high dose of radiation historically utilized in adult patients and the sensitivity of developing pediatric normal tissue. The purpose of this study was to report the outcomes of pediatric EN treated with proton radiotherapy.

MATERIALS/METHODS

Using an IRB-approved, single institutional prospective outcomes registry, we analyzed disease control and toxicity in pediatric patients with non-metastatic EN treated with a multimodality approach, including proton radiotherapy, between March 2008 and March 2022. Of the 15 patients, 8 were female, and 7 were male. The median age was 16 years (range, 3-21 years). Patients were Kadish stage B (n = 2), C (n = 8), and D (n = 5) and Hyams low-grade (n = 9), high-grade (n = 5), and not specified (n = 1). Six patients had intracranial involvement, 4 had cranial nerve deficits, and 4 had positive cervical lymph nodes. Prior to radiation, 2 patients had a subtotal resection and 13 had a gross total resection via either endoscopic (n = 8) or craniofacial (n = 7) approaches. Two patients underwent neck dissection (one unilateral and one bilateral). A total of 11 patients received chemotherapy before (n = 5), concurrent (n = 4) with radiation, or both (n = 2). The median total radiation dose delivered to the primary site was 66 Gy/CGE (range, 59.4-72.8 Gy/CGE) for patients with gross disease and 54 Gy/CGE (range, 54-74.4 Gy/CGE) for patients with microscopic disease.

RESULTS

With a median follow-up of 4.8 years (range, 0.1-12.2 years), both the 5-year disease free and overall survival rates were 86%. There were no local or regional recurrences. Two patients with Kadish D, high grade tumors developed vertebral metastases and died with disease. Serious acute toxicity included 2 patients requiring a temporary feeding tube for oral mucositis/dysphagia. Serious late toxicity included symptomatic retinopathy (n = 3), major reconstructive surgery (n = 2), cataracts requiring intervention (n = 2), chronic otitis media (n = 2), chronic keratoconjunctivitis (n = 2), hypothyroidism (n = 2), and in-field basal cell skin cancer (n = 1).

CONCLUSION

A multimodality approach to pediatric EN results in excellent local control. Despite the use of moderate dose proton therapy, serious radiation toxicity was observed and thus select patients may benefit from further dose and target volume reduction. Longer follow-up and comparative data from modern photon series are necessary to fully characterize any relative advantage of proton therapy.

Building a Diverse Pathway into Radiation Oncology: The Initial 12-Year Experience of the ASTRO Medical Student Fellowship Program for Underrepresented Populations

PURPOSE/OBJECTIVE(S)

Historic radiation oncology (RO) workforce trends reveal underrepresentation and lack of inclusion of racial and ethnic groups underrepresented in medicine (UIM). In 2010, ASTRO's Healthcare Access and Training Subcommittee - the predecessor of today's Committee on Health Equity, Diversity, and Inclusion - launched the Medical Student Fellowship (MSF), which provides an 8-week clinical and research experience, ASTRO mentorship, and a $5,000 stipend. Here, we premier 12-year MSF outcomes to 1) characterize the cohort, 2) identify predictors of successfully awarded applicants, and 3) determine predictors for entering RO residency.

MATERIALS/METHODS

Demographic characteristics of MSF applicants were retrospectively analyzed. Primary endpoints were awarded MSF and RO match. Applicant data were collected from the ASTRO registry, MSF database, and online searches. Race, gender, medical school rank/region, mentor research center rank/region, application year, research type, RO residency affiliation, and award outcomes were collected. Descriptive statistics were tabulated. Univariable and multivariable logistic regression models calculated adjusted odds ratios (aOR) and 95% confidence intervals (95% CI) for factors associated with MSF award receipt and matching into RO residency for those who applied via the Match.

RESULTS

Between 2010 and 2022, there were 101 MSF applicants (74 Clinical and 27 Basic Science) for a total of 39 available funded MSF awards, with an overall MSF award rate of 39%. Applicants were 62% Black, 32% Hispanic, 3% Asian, 1% American Indian or Alaska Native (AIAN), and 1% Native Hawaiian or other Pacific Islander (NHPI). Women comprised 42% of applicants and 51% of awardees. Awardees were 72% Black, 26% Hispanic, and 3% NHPI. By region, awardees were from medical schools in the South (44%), Northeast (31%), Midwest (18%), West (5%), and Caribbean (2%). Since 2010, among applicants, 63% matched into residency and 40% matched to RO. Among the 21 MSF awardees eligible for the Match, 13 (62%) pursued RO with 100% matched into RO. On adjusted analysis, no significant factors predicted a successful MSF application. However, among those who entered residency the only variable that predicted matching into RO was a successful MSF award (aOR = 4.1; 95% CI = 1.1-11.2). To date, MSF awardees who completed RO residency entered academic careers post-residency.

CONCLUSION

The first 12 years of the MSF program demonstrate an overall high rate of recruitment and retention into RO. Retention of women and recruitment of Indigenous students in the MSF are an unmet need. Future efforts and increased funding are needed to further expand the MSF program, understand student barriers, provide longitudinal engagement, train mentors, and increase recruitment and retention of UIM groups in the field.

Outcomes Following Proton Therapy for Non-Metastatic Central Nervous System Germinoma in Children and Adolescents

PURPOSE/OBJECTIVE(S)

Radiation is a key component in the treatment of central nervous system pure germinoma (PG) in children and adolescents. Compared to photons, proton therapy (PT) improves normal tissue sparing and potentially reduces adverse effects, but there are sparse data on long-term patient outcomes. Herein, we present the largest reported single institution experience utilizing PT for the management of PG.

MATERIALS/METHODS

We performed an IRB-approved retrospective review of a prospective database containing 35 patients with non-metastatic PG treated with PT between July 2007 and September 2021. The median age at treatment was 13 years. All patients had > 6 months of follow up. Two patients were diagnosed based on cerebral spinal fluid B-HCG levels and the remaining 33 patients through histopathology. Eleven patients had bifocal or multifocal intracranial disease. Most patients (n = 31, 88.6%) received induction chemotherapy with carboplatin + etoposide (n = 25, 80.6%) with all demonstrating a radiographic response to neoadjuvant therapy. Twenty-nine were treated with whole ventricular irradiation (WVI) with an involved field (IF) boost, 2 with craniospinal irradiation + WVI + IF, 2 with IF, 1 with CSI + IF, and 1 with whole brain + IF. Among this subgroup, the most common total dose was 30 GyRBE (n = 18, 51.4%). Of the 4 patients that did not receive chemotherapy, 3 received WVI + IF and 1 was treated with CSI + WVI + IF. The total dose in the patients not receiving chemotherapy was 45 GyRBE. Twenty-nine patients were treated with double scattered PT (DS) and 6 patients with pencil beam scanning PT (PBS). We utilized the cumulative incidence method to estimate local control (LC), freedom from distant metastases (FFDM), freedom from progression (FFP), and overall survival (OS). Treatment related toxicity was assessed according to the CTCAEv5.

RESULTS

Median follow up was 6.2 years (Range: 0.9-15.2 years). The 10-year KM estimates for LC, FFDM, FFP, and OS were 100%, 100%, 100%, and 97% respectively. One patient developed acute lymphocytic leukemia 8 months after treatment and died. The sole ³ grade 3 radiation-related toxicity was a cavernoma with hemorrhage 3.6 years post treatment requiring surgical resection. The most common adverse events were hearing impairment requiring hearing aids (n = 3), hypersomnia requiring medication (n = 3), and new onset endocrinopathy (n = 1). Of the 22 evaluable patients ³18 years old at last follow up, 7 were high school graduates/in college, 8 college graduates, and 5 others gainfully employed.

CONCLUSION

The use of proton therapy in the multi-modality approach to non-metastatic PG does not compromise local control. Although serious side effects are rare and treatment has minimal impact on survivors' early educational/career trajectory, the 100% cure rate supports further investigation into selective radiation dose and volume de-escalation.

Evaluating Childcare Support in NCI Designated Cancer Centers for Patients with Young Children Undergoing Treatment

PURPOSE/OBJECTIVE(S)

The daily nature of radiotherapy treatment can be challenging for parents diagnosed with cancer who have young children. Access to affordable and convenient childcare can be a considerable hurdle to treatment adherence. We aim to determine the breadth of childcare services and support provided by NCI-designated cancer centers to decrease the burden and stress of receiving radiotherapy treatment of patients with children.

MATERIALS/METHODS

We conducted a cross-sectional survey of the 70 NCI-designated cancer centers. Centers were originally contacted by phone call utilizing their publicly available website, and the researcher asked to speak with the radiation oncology department social worker. Calls were conducted from June 2022 through February 2023. As a result of low response rate, a second methodological design was developed through a collaboration with Association for Directors of Radiation Oncology Programs (ADROP) whereby their listserv was utilized to connect with social workers. For both query designs, social workers were asked what childcare services are offered by the center, if such services are internal, if patients are referred to external organizations, as well as if such organizations operate charitably or require payment for their services. Centers were stratified by type of childcare support offered and compared across private versus public institutions.

RESULTS

Sixty-three of the 70 NCI-designated cancer centers were contacted for data collection, excluding 6 identified as basic laboratories and 1 center serving only pediatric patients. Contact was established with the social work department of 39 cancer centers (62%), of which only 19 (49%) had a radiation oncology departmental social worker. Response data were gathered from 11 (58%) total centers regarding their childcare services. Of the centers surveyed, 10 (91%) indicated the primary form of support offered was via referral to external organizations. Four centers (36%) described offering financial support for childcare, three of which are privately-funded institutions. When queried about the need for childcare support provided by cancer centers, 4 of the 5 surveyed public institutions expressed a need for expansion of these services; the 6 private institutions denied a need for these services among their patient population.

CONCLUSION

Lack of access to childcare presents a significant burden to adherence to radiotherapy among parents undergoing radiotherapy with young children. Our study showed that external community organizations currently play a crucial role in providing childcare support to parents with cancer and demonstrates an inequity between private and public institutions in the perceived need of childcare support for their patients as well as ability to offer direct financial support.

A prospective study of the usefulness of clinical and laboratory parameters for predicting percentage of dehydration in children

To evaluate the relative utility of clinical and laboratory parameters of dehydration in children for predicting the magnitude of percent less of body weight (PLBW), we studied 97 children who required intravenous fluids for acute dehydration. After a complete history and physical examination, the managing physician made a clinical estimation of dehydration for each child, based on a standard clinical scale. Serum electrolytes were obtained in all children prior to intravenous hydration therapy. PLBW was calculated after recovery from acute dehydration by comparing the weight on presentation to the emergency department with the weight measured at a follow-up visit when the child was judged well. Children were classified according to PLBW into three groups which reflect the categories in a standard clinical scale: mild = PLBW < or = 5 (n = 50), moderate = PLBW 6-10 (n = 30), and severe = PLBW > 10 (n = 17). The physician's clinical estimate of dehydration compared to PLBW had a sensitivity of 74% (95% confidence interval (CI): 60-85) for mild dehydration, 33% (95% CI: 17-53) for moderate dehydration, and 70% (95% CI: 44-89) for severe dehydration. There was a significant difference in the mean serum bicarbonate concentrations (HCO3) between the PLBW groups (P < 0.01). The sensitivity of the HCO3 < 17 mEq/L in predicting PLBW was 77% (95% CI: 58-90) for PLBW 6-10, and 94% (95% CI: 71-100) for PLBW > 10. The combination of the clinical scale and the serum bicarbonate identified all 17 children with PLBW > 10 and 90% (27 of 30) children with PLBW 6-10. Our data suggest that physicians should not rely solely on clinical assessment to rule out severe dehydration in children, and that obtaining a serum bicarbonate may improve the accuracy of predicting serious dehydration.