The purpose of this study was to address the lack of published data on the use of brachytherapy in pediatric rhabdomyosarcoma by describing current practice as starting point to develop consensus guidelines. An international expert panel on the treatment of pediatric rhabdomyosarcoma comprising 24 (pediatric) radiation oncologists, brachytherapists and pediatric surgeons met for a Brachytherapy Workshop hosted by the European paediatric Soft tissue Sarcoma Study Group (EpSSG). The panel's clinical experience, the results of a previously distributed questionnaire, and a review of the literature were presented. The survey indicated the most common use of brachytherapy to be in combination with tumor resection, followed by brachytherapy as sole local therapy modality. HDR was increasingly deployed in pediatric practice, especially for genitourinary sites. Brachytherapy planning was mostly by 3D imaging based on CT. Recommendations for patient selection, treatment requirements, implant technique, delineation, dose prescription, dose reporting and clinical management were defined. Consensus guidelines for the use of brachytherapy in pediatric rhabdomyosarcoma have been developed through multicenter collaboration establishing the basis for future work. These have been adopted for the open EpSSG overarching study for children and adults with Frontline and Relapsed RhabdoMyoSarcoma (FaR-RMS).

Radiotherapy is an indispensable treatment modality in the management of rhabdomyosarcoma. Numerous efforts have been made to improve outcomes. The current thinking and future developments in the radiation oncology field about how to raise cure rates, especially in the highest-risk patients, are presented.

Phelan-McDermid syndrome is an inherited global developmental disorder commonly associated with autism spectrum disorder. Due to a significantly increased radiosensitivity, measured before the start of radiotherapy of a rhabdoid tumor in a child with Phelan-McDermid syndrome, the question arose whether other patients with this syndrome also have increased radiosensitivity. For this purpose, the radiation sensitivity of blood lymphocytes after irradiation with 2Gray was examined using the G0 three-color fluorescence in situ hybridization assay in a cohort of 20 patients with Phelan-McDermid syndrome from blood samples. The results were compared to healthy volunteers, breast cancer patients and rectal cancer patients. Independent of age and gender, all but two patients with Phelan-McDermid syndrome showed significantly increased radiosensitivity, with an average of 0.653 breaks per metaphase. These results correlated neither with the individual genetic findings nor with the individual clinical course, nor with the respective clinical severity of the disease. In our pilot study, we saw a significantly increased radiosensitivity in lymphocytes from patients with Phelan-McDermid syndrome, so pronounced that a dose reduction would be recommended if radiotherapy had to be performed. Ultimately, the question arises as to the interpretation of these data. There does not appear to be an increased risk of tumors in these patients, since tumors are rare overall. The question, therefore, arose as to whether our results could possibly be the basis for processes, such as aging/preaging, or, in this context, neurodegeneration. There are no data on this so far, but this issue should be pursued in further fundamentally based studies in order to better understand the pathophysiology of the syndrome.

Diffuse midline glioma (DMG) continues to be an aggressive brain stem cancer among children and young adults. It has a dismal prognosis, with less than 10% of patients alive two years after diagnosis. Radiotherapy has been demonstrated to be effective, albeit transient. Hence, radiotherapy is considered a cornerstone in the treatment. Reirradiation has, in retrospective studies, shown promising overall survival and palliative effect, but no pan-European consensus for reirradiation exists. The REMIT (Reirradiation of diffuse Midline glioma paTients) protocol evaluates safety and the palliative efficacy of reirradiation of patients with DMG (clinicaltrials.gov NCT06093165). Patients included in the protocol will be followed with 1) performance status (Karnofsky or Lansky), 2) toxicity monitored with Common Terminology Criteria for Adverse Events (CTCAE), 3) motor and functioning skill with PEDI-CAT (The Pediatric Evaluation of Disability Inventory) and 4) quantification of corticosteroid use. Furthermore, the impact on quality of life and well-being will be assessed qualitatively with interviews as well as with the Pediatric Quality of Life Inventory (PedsQl) Cancer Module questionnaire. The protocol also includes dose accumulation and contouring studies to assess standardization as well as a prescreening log to address selection bias of patients. The safety and palliative efficacy of reirradiation in DMG will be prospectively evaluated, including qualitative patient reported outcomes, through the REMIT protocol. REMIT is planned to open for inclusion in 2024.

A 62-year-old woman underwent a second surgery for a WHO grade 1 tuberculum sellae meningioma 4 years after her primary resection. The meningioma affected her right optic nerve, and there was a microscopic residual tumor after the second surgery. Due to the history of recurrence, residual tumor, and visual decline, she was offered postoperative radiation therapy of 1.8 Gy in 29 fractions, with a total dose of 52.2 Gy. Maximum doses to the anterior optic pathway structures were 53.7 Gy to the chiasm, 53.3 Gy to the right optic nerve, and 52.3 Gy to the left optic nerve. Following a transient improvement, her vision rapidly worsened 7 to 8 months later, with only finger counting possible in her left eye and a nearly total visual field loss. Visual acuity was reduced to 20/60 in the right eye, the visual field was reduced (especially in the lower 2 quadrants), and radiation-induced optic neuropathy (RION) was suspected. A rare yet disabling condition that may occur following radiation therapy, RION usually presents with painless, rapid visual deterioration in 1 or both eyes. Treatment options are limited, rendering this a devastating radiotherapeutic complication. Systemic steroids were administered to the patient without visual improvement. Bevacizumab was given as a last effort and, after 3 courses, MRI showed some improvement, with regression of presumed inflammatory changes in both optic nerves. However, the patient’s visual function further deteriorated bilaterally. Three additional bevacizumab courses had no effect, neither visually nor radiographically. This case illustrates that despite precautions, including using doses considered relatively safe when planning radiation therapy, RION might develop and may have devastating consequences. Mitigating treatment options are limited.