Volumetric Modulated Arc Therapy Craniospinal Irradiation Utilizing a Vertebral Body Sparing Approach: An Alternative Approach to Improve Access and Minimize Toxicity.

Introduction: Craniospinal irradiation (CSI) is indicated for adult patients diagnosed with leptomeningeal disease (LMD). Proton-based vertebral body sparing (VBS) CSI has been explored with pediatric patients to minimize hematologic toxicity; however, utilization of VBS in an adult population is limited. A recent phase II trial has shown efficacy of proton-based CSI to treat non-small cell lung and breast cancer with LMD. We hypothesize that VBS CSI using volumetric modulated arc therapy (VMAT) could also effectively reduce dose to vertebral bodies and surrounding organs at risk, minimizing toxicity for adult patients with LMD and comparing favorably to proton-based CSI. Methods and Materials: Consecutive patients with LMD received VMAT VBS CSI, 30 Gy in 10 fractions, as a part of a prospective registry. Full VMAT arcs for the brain fields matched to 2 spine isocenters for the upper and lower spine were created using limited posterior arcs. To further decrease the vertebral body dose, an avoid entry and exit contour was created. Acute toxicity data were collected using Common Terminology Criteria for Adverse Events v5. Results: Ten adult patients were treated in this cohort. One patient experienced grade 2 neutropenia with the remaining 9 experiencing grade 1 hematologic toxicity. Three patients experienced grade 2 gastrointestinal toxicity with the remaining 7 experiencing grade 1 nausea. No patient experienced grade 3+ toxicities in this cohort. One patient experienced a 5-day delay in systemic therapy initiation due to neutropenia; otherwise, all patients planned for systemic therapy started without delay. Conclusions: In this study, VMAT VBS CSI led to acceptable toxicity compared with patients treated with proton CSI on a phase 2 clinical trial. Given its promising early results, future prospective evaluation of the technique is warranted.

Clinical outcomes and efficacy of stereotactic body radiation therapy in children, adolescents, and young adults with metastatic solid tumors.

OBJECTIVE: The objective of this study is to report disease outcomes and toxicity with the use of stereotactic body radiation therapy (SBRT) in the treatment of pediatric metastatic disease. METHODS: All pediatric and adolescent young adult (AYA) patients' who received SBRT were included between the years 2000 and 2020. Study endpoints included local control (LC), progression-free survival (PFS), overall survival (OS), cumulative incidence (CI) of death or local failure and toxicity. The end points with respect to survival and LC were calculated using the Kaplan-Meier estimate. The cumulative incidence of local failure was calculated using death as a competing risk. RESULTS: 16 patients with 36 lesions irradiated met inclusion criteria and formed the study cohort. The median OS and PFS for the entire cohort were 17 months and 15.7 months, respectively. The 1 year OS for the entire cohort was 75%. The 6- and 12 month local control was 85 and 78%, respectively. There were no local failures in irradiated lesions for patients who received a BED10≥100 Gy. Patients who were treated with SBRT who had ≤5 metastatic lesions at first recurrence had a superior 1 year OS of 100 vs 50% for those with >5 lesions. One patient (6.3%) experienced a Grade 3 central nervous system toxicity. CONCLUSION: LC was excellent with SBRT delivered to metastatic disease, particularly for lesions receiving a BED10≥100 Gy. High-grade toxicity was rare in our patient population. Patients with five or fewer metastatic sites have a significantly better OS compared to >5 sites. ADVANCES IN KNOWLEDGE: This study demonstrates that SBRT is safe and efficacious in the treatment of pediatric oligometastatic disease.

Radiation Therapy Without Anesthesia for a 2-Year-Old Child Using Audio-Visual Assisted Therapeutic Ambience in Radiation Therapy (AVATAR).

PURPOSE: Radiation therapy (RT) is essential to managing many pediatric malignancies but can provoke anxiety, fear, and discomfort for children owing to prolonged treatment time, extended course, and restrictive immobilization. Patients younger than 10 years frequently require daily general anesthesia (GA), which is resource intensive, expensive, potentially toxic, and anxiety and fear provoking. Audio-Visual Assisted Therapeutic Ambience in Radiation Therapy (AVATAR), a video streaming device, has been proposed as an alternative to anesthesia in patients aged 3 to 10 years. A pilot study evaluating the efficacy of this novel innovation is accruing, but patients younger than 3 years are ineligible. METHODS AND MATERIALS: We simulated a 2-year-old with stage IV Wilms tumor for bilateral whole-lung and left-flank irradiation without GA. Using AVATAR, we attempted to deliver RT to this patient without sedation. Patient anxiety at the time of simulation and at the beginning, middle, and end of the treatment course was characterized using the validated Modified Yale Preoperative Anxiety Score (mYPAS) measurement tool. RESULTS: Although the patient tolerated computed tomography simulation without GA or AVATAR use, his mYPAS of 14 out of 18 indicated significant anxiety. Using AVATAR, all treatments were delivered without GA; his mYPASs were 5 and 4 (the lowest possible) and 4 at the first, midcourse, and final treatments, indicating no significant anxiety and a decrease from the pre-AVATAR baseline. Without GA, the time to deliver RT decreased by 66% from 90 to 30 minutes. CONCLUSIONS: We describe an expanded, previously unreported indication for AVATAR by demonstrating the feasibility of this approach to reduce or omit anesthesia in appropriate younger patients currently excluded from ongoing trials. The financial and quality-of-life benefits (including decreased stress, anxiety, toxic effects, cost, and appointment time) of AVATAR use may be extendable to a younger patient population than previously thought. In older children, prospective validation is ongoing, but additional study in patients younger than 3 years is needed.

Risks of secondary malignancies with heterotopic bone radiation therapy for patients younger than 40 years.

Heterotopic ossification (HO) of the bone is defined as a benign condition in which abnormal bone formation occurs in soft tissue. One of the most common prophylactic treatments for HO is radiation therapy (RT). This study retrospectively reviewed 20 patients younger than the age of 40 who received radiation to prevent HO in a single fraction of 7 Gray. The purpose of this study is to assess the risk of a second malignancy in these patients by recreating their treatment fields and contouring organs at risk to estimate the radiation dose absorbed by normal tissues outside the radiation treatment field. Diagnostic computed tomography (CT) scans for each patient were used to recreate treatment fields and to calculate dose to structures of interest. The distance from the field edge to each structure and its depth was recorded. Dose measurements in a water phantom were performed for the range of depths, distances, and field sizes used in the actual treatment plans. Computer-generated doses were compared to estimates based on measurement. The structure dose recorded was the higher dose generated between the 2 methods. Scatter dose was recorded to the rectum, bladder, sigmoid colon, small bowel, ovaries and utero-cervix in female patients, and prostate and gonads in male patients. In some patients, there is considerable dose received by certain organs from scatter because of their proximity to the radiation field. The average dose to the ovarian region was 4.125Gy with a range of 1.085 to 6.228Gy. The risk estimate for these patients ranged from 0.16% to 0.93%. The average total lifetime risk estimate for the bladder in all patients is 0.22% and the average total lifetime risk estimate for the remainder organs in all patients is 1.25%. In conclusions, proper shielding created from multileaf collimators (MLCs), blocks, and shields should always be used when possible.