Association between Radiation Dose and Local Failure in Recurrent High-Risk Neuroblastoma

PURPOSE/OBJECTIVE(S)

Historically, standard-of-care (SoC) for high-risk neuroblastoma recurrences is irradiation to 2160 cGy for gross or microscopic disease. Boosting gross disease to 3000-3600 cGy remains controversial. Prior reports have demonstrated worse local control with gross disease irradiated to <3000 cGy. We sought to evaluate whether higher radiation doses delivered to sites of recurrence affected local control.

MATERIALS/METHODS

We identified seventy-five high-risk neuroblastoma patients aged 6 months to 26 years that completed definitive treatment between 2007 and 2021 at two large academic centers. Only patients with distant recurrences treated with radiotherapy were included for analysis. Treatments were stratified into 1800-2160 cGy or 3000-3600 cGy dose levels. Local failure after irradiation was defined as progression within the radiation field after salvage RT. The Fine-Gray competing risk model was used to identify cumulative incidence of local failure (CILF) after irradiation with competing risk of death.

RESULTS

Thirteen patients experienced recurrence after completion of definitive treatment, representing 30 metastatic lesions. Thirteen lesions received 1800-2160 cGy and seventeen received 3000-3600 cGy. With a median follow-up of 42.0 months (IQR 30.8-60.8), local failure after irradiation occurred in 10% (3/30) of metastatic lesions. Median time to failure was 7 months. All three failures had been treated to 2160 cGy; two in the calvarium and one in the femur. There were no local failures among patients treated to 3000-3600 cGy. The 1-year and 2-year CILF for the low- versus high-dose levels were 15% versus 0% (p<0.01) and 25% versus 0% (p<0.01), respectively. Four of the 13 patients (31%) died at a median time of 12.5 months after first recurrence; all four had distant recurrences.

CONCLUSION

Dose-escalated irradiation ≥3000 cGy was associated with improved local control in recurrent high-risk neuroblastoma; prospective study and validation is warranted.

Radiotherapy for Atypical Teratoid/=Rhabdoid Tumor (ATRT) on the Pediatric Proton/Photon Consortium Registry (PPCR)

PURPOSE

Atypical teratoid/rhabdoid tumors (ATRT) of the central nervous system (CNS) are rare tumors with a poor prognosis and variable use of either focal or craniospinal (CSI) radiotherapy (RT). Outcomes on the prospective Pediatric Proton/Photon Consortium Registry (PPCR) were evaluated according to RT delivered.

METHODS

Pediatric patients receiving RT were prospectively enrolled on PPCR to collect initial patient, disease, and treatment factors as well as provide follow-up for patient outcomes. All ATRT patients with evaluable data were included. Kaplan-Meier analyses with log-rank p-values and cox proportional hazards regression were performed.

RESULTS

The PPCR ATRT cohort includes 68 evaluable ATRT patients (median age 2.6 years, range 0.71-15.40) from 2012 to 2021. Median follow-up was 40.8 months (range 3.4-107.7). Treatment included surgery (65% initial gross total resection or GTR), chemotherapy (60% with myeloablative therapy including stem cell rescue) and RT. For patients with M0 stage (n = 60), 50 (83%) had focal RT and 10 (17%) had CSI. Among patients with M + stage (n = 8), 3 had focal RT and 5 had CSI. Four-year overall survival (OS, n = 68) was 56% with no differences observed between M0 and M + stage patients (p = 0.848). Local Control (LC) at 4 years did not show a difference for lower primary dose (50-53.9 Gy) compared to ≥ 54 Gy (73.3% vs 74.7%, p = 0.83). For patients with M0 disease, four-year OS for focal RT was 54.6% and for CSI was 60% (Hazard Ratio 1.04, p = 0.95. Four-year event free survival (EFS) among M0 patients for focal RT was 45.6% and for CSI was 60% (Hazard Ratio 0.71, p = 0.519). For all patients, the 4-year OS comparing focal RT with CSI was 54.4% vs 60% respectively (p = 0.944), and the 4-year EFS for focal RT or CSI was 42.8% vs 51.4% respectively (p = 0.610).

CONCLUSION

The PPCR ATRT cohort found no differences in outcomes according to receipt of either higher primary dose or larger RT field (CSI). However, most patients were M0 and received focal RT. A lower primary dose (50.4 Gy), regardless of patient age, is appealing for further study as part of multi-modality therapy.

RADT-21. PATTERNS OF CARE AND OUTCOMES IN PEDIATRIC HIGH-GRADE GLIOMA PATIENTS ENROLLED IN THE PEDIATRIC PROTON/PHOTON CONSORTIUM REGISTRY

BACKGROUND

Proton therapy (PRT) is increasingly utilized for pediatric brain tumors to reduce radiation associated treatment effects, but there is a lack of data evaluating PRT in pediatric high-grade glioma (pHGG). The purpose of this analysis is to report patterns of care and clinical outcomes for pHGG patients treated with PRT and enrolled in the prospective Pediatric Proton/Photon Consortium Registry (PPCR).

METHODS

Fifty-five pHGG participants treated with PRT were enrolled in the PPCR between Jan 2013 and Aug 2020. Progression free (PFS) and overall survival (OS) rates were calculated according to the Kaplan-Meier method. Univariate analyses were performed using Cox proportional hazards model with Firth’s penalization.

RESULTS

Among 49 patients with complete data, the median age was 12, the majority of patients were male (29), white (35), and non-Hispanic/Latino (41). Histology was grade IV (37), grade III (10) or HGG not specified (8). Resection was gross-total (24), near-total (4), or sub-total/biopsy (17). Six patients received prior RT. The median RT dose was 57.6 Gy (RBE) starting a median of 33.5 days after surgery. 39 patients received chemotherapy. The most common acute treatment toxicities were alopecia (36), fatigue (34), radiation dermatitis (22), nausea/vomiting (19), and headache (19). Median follow-up was 3.14 years (95% CI 1.62-3.97). At 3 years, PFS (95% CI) was 35.5% (20.8-50.6%) and OS was 55.6% (38-70%). Median PFS and OS are 1.6 (1.2-3.1) and 3.6 (1.6-NA) years, respectively. Higher radiation dose was associated with greater PFS (HR 0.97 (0.94-1.01), p=0.059) and OS (HR 0.95 (0.93-0.99), p=0.006). Patients ≤ 3 years at diagnosis (n=8) had 3-year PFS/OS of 72.9%/87.5% vs. 27.8%/49.4% for older patients (p=0.068/0.089, respectively).

CONCLUSION

These are the first published data with PRT for pHGG. Clinical outcomes are comparable to historical data with photon therapy. Additional analysis of treatment associated toxicity and patient quality-of-life are warranted.

Volumetric de-escalation and improved acute toxicity with proton craniospinal irradiation using a vertebral body-sparing technique

PURPOSE

In growing children, craniospinal irradiation (CSI) has historically treated the entire vertebral body (VB) to avoid potential long-term spinal abnormalities. Vertebral body-sparing proton craniospinal irradiation (VBSpCSI) is a technique that spares the majority of the VB from significant irradiation, and long-term safety outcomes have been reported previously. This retrospective study reviews the acute toxicity profile of children treated with VBSpCSI in a cohort comparison with photon-based craniospinal radiotherapy (3DCRT).

METHODS

Thirty-eight pediatric CSI patients treated between 2008 and 2018 were retrospectively evaluated for treatment-related toxicity. Acute toxicity outcomes and acute hematologic profiles were compared according to treatment modality, either VBSpCSI or 3DCRT. Statistical analysis was performed using Fisher's exact test for toxicity.

RESULTS

Twenty-five patients received VBSpCSI and 13 patients received photon CSI. Mean patient age at treatment was 7.5 years (range 2-16). The cohorts were well matched with respect to gender, age, and CSI dose. Patients receiving VBSpCSI had lower rates of grade 2+ gastrointestinal (GI) toxicity (24% vs. 76.5%, p = .005), grade 2+ nausea (24% vs. 61.5%, p = .035), and any-grade esophagitis (0% vs. 38%, p = .0026). Patients treated with VBSpCSI had lower red blood cell transfusion rates (21.7% vs. 60%, p = .049) and grade 4+ lymphopenia (33.3% vs. 77.8%, p = .046).

CONCLUSIONS

VBSpCSI in children is a volumetric de-escalation from traditional volumes, which irradiate the entire VB to full or intermediate doses. In our study, VBSpCSI was associated with lower rates of acute GI and hematologic toxicities. Long-term growth outcomes and disease control outcomes are needed for this technique.

Toward automatic beam angle selection for pencil-beam scanning proton liver Treatments: A deep learning-based approach

BACKGROUND

Dose deposition characteristics of proton radiation can be advantageous over photons. Proton treatment planning however poses additional challenges for the planners. Proton therapy is usually delivered with only a small number of beam angles, and the quality of a proton treatment plan is largely determined by the beam angles employed. Finding the optimal beam angles for a proton treatment plan requires time and experience, motivating the investigation of automatic beam angle selection methods.

PURPOSE

A deep learning-based approach to automatic beam angle selection is proposed for proton pencil-beam scanning treatment planning of liver lesions.

METHODS

We cast beam-angle selection as a multi-label classification problem. To account for angular boundary discontinuity, the underlying convolution neural network is trained with the proposed Circular Earth Mover's Distance based regularization and multi-label circular-smooth label technique. Furthermore, an analytical algorithm emulating proton treatment planners' clinical practice is employed in post-processing to improve the output of the model. Forty-nine patients that received proton liver treatments between 2017 and 2020 were randomly divided into training (n = 31), validation (n = 7), and test sets (n = 11). AI-selected beam angles were compared with those angles selected by human planners, and the dosimetric outcome was investigated by creating plans using knowledge-based treatment planning.

RESULTS

For 7 of the 11 cases in the test set, AI-selected beam angles agreed with those chosen by human planners to within 20 degrees (median angle difference = 10°; mean = 18.6°). Moreover, out of the total 22 beam angles predicted by the model, 15 (68%) were within 10 degrees of the human-selected angles. The high correlation in beam angles resulted in comparable dosimetric statistics between proton treatment plans generated using AI- and human-selected angles. For the cases with beam angle differences exceeding 20°, the dosimetric analysis showed similar plan quality although with different emphases on organ-at-risk sparing.

CONCLUSIONS

This pilot study demonstrated the feasibility of a novel deep learning-based beam angle selection technique. Testing on liver cancer patients showed that the resulting plans were clinically viable with comparable dosimetric quality to those using human-selected beam angles. In tandem with auto-contouring and knowledge-based treatment planning tools, the proposed model could represent a pathway for nearly fully automated treatment planning in proton therapy. This article is protected by copyright. All rights reserved.

Disseminated protothecosis with central nervous system involvement in a dog in New Zealand

CASE HISTORY

A 1-year-old Border Terrier presented with acute onset of neurological signs and neck pain.

CLINICAL FINDINGS

Severe generalised ataxia, muscle tremors and cranial nerve deficits were noted. Multifocal brain lesions were suspected based on neurological examination. Computed tomography revealed an abdominal mass and cerebellar herniation through the foramen magnum.

LABORATORY AND PATHOLOGICAL FINDINGS

Cytological and histopathological analysis of the abdominal mass revealed necrotising and granulomatous lymphadenitis with intralesional algal elements most consistent with Prototheca spp.. Culture of a sample from the mesenteric lymph node confirmed the presence of Prototheca spp. which was identified as P. bovis based on sequencing of a DNA fragment amplified by PCR. Following inadequate response to symptomatic therapy and poor prognosis, the dog was subjected to euthanasia. Histopathological evaluation of the central nervous system lesions, identified granulomatous meningitis and ventriculitis with the presence of intralesional algae.

DIAGNOSIS

Disseminated protothecosis with granulomatous meningitis and ventriculitis caused by Prototheca bovis (formerly P. zopfii gen. 2).

CLINICAL RELEVANCE

This is the first case report of disseminated protothecosis with central nervous system involvement in a dog in New Zealand.

Wilms Tumor (Nephroblastoma), Version 2.2021, NCCN Clinical Practice Guidelines in Oncology

The NCCN Guidelines for Wilms Tumor focus on the screening, diagnosis, staging, treatment, and management of Wilms tumor (WT, also known as nephroblastoma). WT is the most common primary renal tumor in children. Five-year survival is more than 90% for children with all stages of favorable histology WT who receive appropriate treatment. All patients with WT should be managed by a multidisciplinary team with experience in managing renal tumors; consulting a pediatric oncologist is strongly encouraged. Treatment of WT includes surgery, neoadjuvant or adjuvant chemotherapy, and radiation therapy (RT) if needed. Careful use of available therapies is necessary to maximize cure and minimize long-term toxicities. This article discusses the NCCN Guidelines recommendations for favorable histology WT.

An open invitation to join the Pediatric Proton/Photon Consortium Registry to standardize data collection in pediatric radiation oncology

OBJECTIVE

The Pediatric Proton/Photon Consortium Registry (PPCR) is a comprehensive data registry composed of pediatric patients treated with radiation. It was established to expedite outcomes-based research. The attributes which allow the PPCR to be a successful collaboration are reviewed.

METHODS AND MATERIALS

Current eligibility criteria are radiotherapy patients < 22 years treated at one of the 15 US participating institutions. Detailed health and treatment data are collected about the disease presentation and treatment exposures, and annually thereafter, in REDCap (Research Electronic Data Capture). DICOM (Digital Imaging and Communications in Medicine) imaging and radiation plans are collected through MIM/MIMcloud. An optional patient-reported quality-of-life (PedsQL) study is administered at 10 sites.

RESULTS

Accrual started October 2012 with 2,775 participants enrolled as of 25 July 2019. Most patients, 62.0%, were treated for central nervous system (CNS) tumors, the most common of which are medulloblastoma (n = 349), ependymoma (n = 309), and glial/astrocytoma tumors (n = 279). The most common non-CNS diagnoses are rhabdomyosarcoma (n = 284), Ewing's sarcoma (n = 153), and neuroblastoma (n = 130). While the majority of participants are US residents, 18.7% come from 36 other countries. Over 685 patients participate in the PedsQL study.

CONCLUSIONS

The PPCR is a valuable research platform capable of answering countless research questions that will ultimately improve patient care. Centers outside of the USA are invited to participate directly or may engage with the PPCR to align data collection strategies to facilitate large-scale international research.

ADVANCES IN KNOWLEDGE

For investigators looking to carry out research in a large pediatric oncology cohort or interested in registry work, this paper provides an updated overview of the PPCR.

The Effect of Urine Concentration and pH on the Growth of Escherichia Coli in Canine Urine In Vitro

Background

Lower urinary tract infections are common in dogs, and Escherichia coli is the most common bacterial pathogen isolated. The literature has conflicting evidence regarding the inhibitory effects of urine concentration and pH on E. coli growth.

Hypothesis/Objectives

To determine the effect of different pH and urine concentrations on E. coli growth in vitro.

Animals

Voided urine samples from 10 apparently healthy spayed female dogs were used.

Methods

A matrix of 9 urine specific gravity (USG; 1.010, 1.020, and 1.030) and pH (5.5, 7.0, and 8.5) combinations was prepared by diluting and titrating filtered voided urine samples. Three E. coli isolates were obtained from urine of female dogs with signs of lower urinary tract infection and cultured at different urine pH and USG combinations in wells of a microtiter plate. The number of E. coli colony‐forming units (CFU) per mL of urine was calculated after aerobic incubation of the urine at 37°C for 18 hours, and statistically compared.

Results

Significant differences were identified in the mean log CFU/mL among different combinations of pH and USG. The lowest log CFU/mL were observed in alkaline concentrated urine (pH 8.5 and USG 1.030).

Conclusions and Clinical Importance

Escherichia coli in vitro growth was higher in neutral to acidic and diluted urine compared to alkaline and concentrated urine. The impact of non‐alkalizing diluting diets on the incidence of E. coli lower urinary tract infections should be further explored.

Effects of vertebral-body-sparing proton craniospinal irradiation on the spine of young pediatric patients with medulloblastoma

Purpose

To investigate the long-term effects of vertebral-body-sparing proton craniospinal irradiation (CSI) on the spine of young patients with medulloblastoma.

Methods and materials

Six children between the ages of 3 and 5 years with medulloblastoma were treated with vertebral-body-sparing proton CSI after maximal safe resection. Radiation therapy was delivered in the supine position with posterior beams targeting the craniospinal axis, and the proton beam was stopped anterior to the thecal sac. Patients were treated with a dose of either 23.4 Gy or 36 Gy to the craniospinal axis followed by a boost to the posterior fossa and any metastatic lesions. Chemotherapy varied by protocol. Radiographic effects on the spine were evaluated with serial imaging, either with magnetic resonance imaging scans or plain film using Cobb angle calculations, the presence of thoracic lordosis, lumbar vertebral body-to-disc height ratios, and anterior-posterior height ratios. Clinical outcomes were evaluated by patient/family interview and medical chart review.

Results

Overall survival and disease free survival were 83% (5/6) at follow-up. Median clinical and radiographic follow-up were 13.6 years and 12.3 years, respectively. Two patients were clinically diagnosed with scoliosis and treated conservatively. At the time of follow-up, no patients had experienced chronic back pain or required spine surgery. No patients were identified to have thoracic lordosis. Diminished growth of the posterior portions of vertebral bodies was identified in all patients, with an average posterior to anterior ratio of 0.88, which was accompanied by compensatory hypertrophy of the posterior intervertebral discs.

Conclusion

Vertebral-body-sparing CSI with proton beam did not appear to cause increased severe spinal abnormalities in patients treated at our institution. This approach could be considered in future clinical trials in an effort to reduce toxicity and the risk of secondary malignancy and to improve adult height.

A randomized controlled trial of motivational enhancement therapy (MET) for mild to moderate alcohol dependence

OBJECTIVE

This study was designed to conduct a randomized controlled trial of motivational enhancement therapy (MET) with two control conditions: nondirective reflective listening (NDRL) and no further counseling (NFC); and to conduct this study in a sample of patients with a primary diagnosis of mild to moderate alcohol dependence, in a "real-life" clinical setting.

METHOD

Patients with mild to moderate alcohol dependence were recruited, assessed and treated at the Community Alcohol and Drug Service of Christchurch, New Zealand. All patients received a feedback/education session before randomization to either four sessions of MET, four sessions of NDRL, or NFC. Outcome data on 122 subjects (57.4% men) were obtained 6 months following the end of treatment, by an interviewer who was blind to the treatment condition. The primary drinking outcome was unequivocal heavy drinking, defined as drinking 10 or more standard drinks six or more times in the follow-up period. Global assessment scale (GAS) measured general personal/social functioning.

RESULTS

Of patients treated with MET, 42.9% showed unequivocal heavy drinking compared with 62.5% of the NDRL and 65.0% of the NFC groups (p = .04). No significant differences were found for GAS score according to treatment condition.

CONCLUSIONS

In patients with mild to moderate alcohol dependence, MET is more effective for reducing unequivocal heavy drinking than either a feedback/education session alone or four sessions of NDRL. MET can be considered an effective "value added" counseling intervention in a real-life clinical setting. In patients with mild to moderate alcohol dependence, nondirective reflective listening provides no additional advantage over a feedback/education session alone.