Mailhot Vega, Raymond B

Abstract Background In children with non-metastatic atypical teratoid/rhabdoid tumor (ATRT), proton therapy is increasingly utilized worldwide due to the radiosensitivity of afflicted young patients. General questions persist, however, surrounding dose and volume of radiotherapy. Methods Between 2009-2024, 39 children from a single institution with non-metastatic intracranial ATRT received focal proton therapy at a median age of 2.4 years (range 0.7-19). Twenty-two patients had supratentorial tumors and 27 had gross/near total resection prior to radiation. Most common chemotherapy regimens were ACNS0333 and SJYC07 (n = 10 each) and Dana-Farber (n = 6). Four patients received consolidative high-dose chemotherapy after radiation. The median radiation dose was 50.4 Gy (range, 50.4-54). The cumulative incidence method assessed freedom from selected endpoints.The Fine-Gray method assessed the level of statistical significance between levels of selected prognostic factors. Results With a median followup of 5.2 years (range 0.5-16.2), the 5-yr overall survival, progression-free survival, and local control was 63%, 64%, and 97%, respectively. Thirteen patients developed isolated leptomeningeal failure as first site of recurrence. Only subtotal resection was significantly associated with local recurrence (100% vs 92%, p < 0.05). Patient age, tumor site, extent of resection, radiation dose, and chemotherapy regimen were otherwise not significantly associated with disease control or survival. Four patients experienced symptomatic radiation necrosis, including 1 death: Three of 4 cases received 54 Gy and consolidative intrathecal methotrexate (n = 2) or high dose ACNS0333 intravenous chemotherapy (n = 1, fatal) after radiation. The other patient received 50.4 Gy and necrosis was immediately preceded by ventriculoperitoneal shunt failure. Six patients developed hearing loss requiring aids. One patient developed radiation-induced meningioma a decade following treatment. Conclusion This represents the largest experience reporting 5-year outcomes following focal radiation in children with non-metastatic intracranial ATRT. When applied with a variety of modern chemotherapy regimens in real-world settings, focal proton therapy at a dose of 50.4 Gy may offer the best therapeutic ratio but does not eliminate serious toxicity. If avoidance of craniospinal radiation remains an ongoing priority, further improvement in survival will depend upon systemic therapy.

PURPOSE Doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) chemotherapy is used commonly for pediatric Hodgkin lymphoma (pHL) in low- and middle-income countries. The role of radiotherapy (RT) after ABVD in pHL is uncertain. MATERIALS AND METHODS We conducted a systematic review to explore the use of ABVD with or without RT in pHL. Key clinical questions included the number of cycles of ABVD, indications for and dose of RT, and outcomes by risk group. A search was performed in PubMed. Articles reporting survival outcomes by risk group were included. RESULTS Of 97 articles identified in the literature search, nine met inclusion criteria. Chemotherapy consisted of four to six cycles in limited disease and mostly six cycles in advanced disease. Three studies used RT for all patients within a specified risk group. Six studies dictated an adapted RT approach, with 3%-43% of the patients receiving RT for bulky adenopathy, slow early response (SER), and/or incomplete response. Radiation doses ranged between 20 and 36 Gy. The progression-free survival and overall survival at 4-10 years ranged from 84% to 100% and 93%-100% in limited disease and 50%-84.4% and 75%-95.3% in advanced disease, respectively. Studies did not directly assess the impact of certain chemotherapy or RT strategies. Recommendations were made after reviewing outcomes with particular approaches. CONCLUSION Four cycles of ABVD are recommended for limited disease, and six cycles of ABVD are recommended for advanced disease. In both limited and advanced diseases, RT is recommended with a dose of 20-21 Gy only to sites of bulky and/or SER, with a boost of up to 36 Gy to sites of incomplete response. This approach could spare radiation for at least half of the patients with limited disease and one third of advanced disease.

AbstractBackgroundPediatric esthesioneuroblastoma (EN) can infiltrate skull base anatomy, presenting challenges due to high radiation doses and pediatric tissue sensitivity. This study reports outcomes of pediatric EN treated with proton radiotherapy (PT).ProcedureUsing an IRB‐approved prospective outcomes registry, we evaluated patient, tumor, and treatment‐related variables impacting disease control and toxicity in pediatric nonmetastatic EN treated with modern multimodality therapy, including PT.ResultsFifteen consecutive patients (median age 16) comprising Kadish stage B (n = 2), C (n = 9), and D (n = 4) tumors were assessed, including six with intracranial involvement, four with cranial nerve deficits, and four with cervical lymphadenopathy. Before radiation, two had subtotal and 13 had gross total resections (endoscopic or craniofacial). Two underwent neck dissection. Eleven received chemotherapy before radiation (n = 5), concurrent with radiation (n = 4), or both (n = 2). Median total radiation dose (primary site) was 66 Gy/CGE for gross disease and 54 Gy/CGE (cobalt Gray equivalent) for microscopic disease. Median follow‐up was 4.8 years. No patients were lost to follow‐up. Five‐year disease‐free and overall survival rates were 86% (no local or regional recurrences). Two patients developed vertebral metastases and died. Two required a temporary feeding tube for oral mucositis/dysphagia. Late toxicities included symptomatic retinopathy, major reconstructive surgery, cataracts, chronic otitis media, chronic keratoconjunctivitis, hypothyroidism, and in‐field basal cell skin cancer.ConclusionsA multimodality approach for pediatric EN results in excellent local control. Despite the moderate‐dose PT, serious radiation toxicity was observed; further dose and target volume reductions may benefit select patients. Longer follow‐up and comparative data from modern photon series are necessary to fully characterize any relative PT advantage.

AbstractBackgroundChildren with chest wall Ewing sarcoma with malignant pulmonary effusion or pleural stranding require hemithorax radiation, often with plans that exceed lung constraints. We investigated disease control and pneumonitis in children requiring hemithorax radiation.ProcedureEleven children (median age 13 years) received hemithorax radiotherapy. Symptomatic radiation pneumonitis was considered National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) grade 1+ with respiratory symptoms. Mean lung dose (MLD), volume of lung exposed to a dose ≥5 Gy (V5), ≥20 Gy (V20), and ≥35 Gy (V35) were recorded. Adult and pediatric lung constraints were obtained from Quantitative Analysis of Normal Tissue Effects in the Clinic (QUANTEC) guidelines and Children's Oncology Group (COG) protocols, respectively.ResultsMedian hemithorax dose was 15 Gy (1.5 Gy/fraction). Median total dose was 51 Gy (1.8 Gy/fraction). Most plans delivered both protons and photons. The ipsilateral MLD, V5, and V20 were 27.2 Gy, 100%, and 48.3%; the bilateral MLD, V20, and V35 were 14.1 Gy, 22.8%, and 14.3%, respectively. One hundred percent, 36%, and 91% of treatments exceeded recommended adult ipsilateral lung constraints of V5 <65%, V20 <52%, and MLD of 22 Gy; 64%, 45%, and 82% exceeded COG bilateral lung constraints of V20 <20%, MLD <15 Gy, and MLD <12 Gy, respectively; 82% of treatments exceeded the COG ipsilateral lung constraint of V20 <30%. At a median 36 months (range 12–129), the symptomatic radiation pneumonitis incidence was 0%. Two patients progressed with nonpulmonary metastatic disease and died at a median 12 months following radiotherapy.ConclusionsExisting guidelines may overestimate pneumonitis risk, even among young children receiving multiagent chemotherapy. For children with chest wall Ewing sarcoma and other thoracic malignancies, more data are needed to refine pediatric dose–effect models for pulmonary toxicity.

Abstract Background Out‐of‐field neutron dissemination during double‐scattered proton therapy has raised concerns of increased second malignancies, disproportionally affecting pediatric patients due to the proportion of body exposed to scatter dose and inherent radiosensitivity of developing tissue. We sought to provide empiric data on the incidence of early second tumors. Methods Between 2006 and 2019, 1713 consecutive children underwent double‐scattered proton therapy. Median age at treatment was 9.1 years; 371 were ≤3 years old. Thirty‐seven patients (2.2%) had tumor predisposition syndromes. Median prescription dose was 54 Gy (range 15–75.6). Median follow‐up was 3.3 years (range 0.1–12.8), including 6587 total person‐years. Five hundred forty‐nine patients had ≥5 years of follow‐up. A second tumor was defined as any solid neoplasm throughout the body. Results Eleven patients developed second tumors; the 5‐ and 10‐year cumulative incidences were 0.8% (95% CI, 0.4–1.9%) and 3.1% (95% CI, 1.5–6.2%), respectively. Using age‐ and gender‐specific data from the Surveillance, Epidemiology, and End Results (SEER) program, the standardized incidence ratio was 13.5; the absolute excess risk was 1.5/1000 person‐years. All but one patient who developed second tumors were irradiated at ≤5 years old ( p < .0005). There was also a statistically significant correlation between patients with tumor predisposition syndromes and second tumors ( p < .0001). Excluding patients with tumor predisposition syndromes, 5‐ and 10‐year rates were 0.6% (95% CI, 0.2–1.7%) and 1.7% (95% CI, 0.7–4.0%), respectively, with all five malignant second tumors occurring in the high‐dose region. Conclusion Second tumors are rare within the decade following double‐scattered proton therapy, particularly among children irradiated at >5 years old and those without tumor predisposition syndrome.