Search

Background and Purpose: As no guidelines for pencil beam scanning (PBS) proton therapy (PT) of paediatric posterior fossa (PF) tumours exist to date, this study investigated planning techniques across European PT centres, with special considerations for brainstem and spinal cord sparing., Materials and Methods: A survey and a treatment planning comparison were initiated across nineteen European PBS-PT centres treating paediatric patients. The survey assessed all aspects of the treatment chain, including but not limited to delineations, dose constraints and treatment planning. Each centre planned two PF tumour cases for focal irradiation, according to their own clinical practice but based on common delineations. The prescription dose was 54 Gy(RBE) for Case 1 and 59.4 Gy(RBE) for Case 2. For both cases, planning strategies and relevant dose metrics were compared., Results: Seventeen (89 %) centres answered the survey, and sixteen (80 %) participated in the treatment planning comparison. In the survey, thirteen (68 %) centres reported using the European Particle Therapy Network definition for brainstem delineation. In the treatment planning study, while most centres used three beam directions, their configurations varied widely across centres. Large variations were also seen in brainstem doses, with a brainstem near maximum dose (D2%) ranging from 52.7 Gy(RBE) to 55.7 Gy(RBE) (Case 1), and from 56.8 Gy(RBE) to 60.9 Gy(RBE) (Case 2)., Conclusion: This study assessed the European PBS-PT planning of paediatric PF tumours. Agreement was achieved in e.g. delineation-practice, while wider variations were observed in planning approach and consequently dose to organs at risk. Collaboration between centres is still ongoing, striving towards common guidelines., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

In this study, we provide a comprehensive clinical and molecular biological characterization of radiation-induced gliomas (RIG), including a risk assessment for developing gliomas. A cohort of 12 patients who developed RIG 9.5 years (3-31 years) after previous cranial radiotherapy for brain tumors or T-cell acute lymphoblastic leukemia was established. The derived risk of RIG development based on our consecutive cohort of 371 irradiated patients was 1.6% at 10 years and 3.02% at 15 years. Patients with RIG glioma had a dismal prognosis with a median survival of 7.3 months. We described radiology features that might indicate the suspicion of RIG rather than the primary tumor recurrence. Typical molecular features identified by molecular biology examination included the absence of Histon3 mutation, methylation profile of pedHGG-RTK1 and the presence of recurrent PDGFRA amplification and CDKN2A/B deletion. Of the two long-term surviving patients, one had gliomatosis cerebri, and the other had pleomorphic xanthoastrocytoma with BRAF V600E mutation. In summary, our experience highlights the need for tissue diagnostics to allow detailed molecular biological characterization of the tumor, differentiation of the secondary tumor from the recurrence of the primary disease and potentially finding a therapeutic target., (© 2024. The Author(s).)

Positron emission tomography (PET) is used to distinguish between benign and malign tumors, to diagnose relapse or post-therapeutic changes. Lately, PET is used to predict the treatment response. and also a complementary method to determine target volumes in radiotherapy. Daily using of PET in the oncology praxis can change treatment strategy and improve its outcome. Results of this pilot study show the role of PET with 8-F-fluorodeoxyglucose ((18)FDG) for staging of cervical carcinoma and in the radiotherapeutic planning. Between March 2005 and May 2007, 51 patients with cervical carcinoma were treated with combination of external beam radiotherapy and HDR brachytherapy, with or without concomitant cisplatin. The lymphatic nodes treatment field size was determined by PET/CT fusion. Treatment results were evaluated by PET 3 and 9 months after treatment. The differences in the results of PET and CT were evaluated in this study. In 32 cases (62.75%) the results of PET and CT were identical, in 14 cases (27.45%) the nodal involvement was more extensive according to PET, in 5 cases (9.8%) the nodal involvement was more extensive according to CT. PET results 3 months after treatment were as follows: in 3 cases (5.88%) stable disease, in 35 cases (68.63 %) negative, in 4 cases (7.84%), progression of disease, in 3 cases (5.88 %) partial regression. There were no false positive results caused by inflammatory reaction persisting 3 months after radiotherapy, as was confirmed by repeating PET 9 months after treatment. The results of this study confirmed the important role of PET in diagnosis and treatment of cervical carcinoma and in determination of target volumes in radiotherapy. PET was found to be a standard staging examination of cervical carcinoma in Masaryk Memorial Cancer Institute. The predictive value of PET has not yet been validated.

Medulloblastoma, a primitive neuroectodermal tumor growing in cerebellum, is one of the most sensitive to radiation therapy childhood brain tumors. The radiotherapy is an essential method of treatment for these tumours, but the surgery is the primary treatment of choice in medulloblastoma. I this study between January 1997 and March 2005 were post-operative irradiated a total number of 33 pediatric patients aged under 15 years (median age 8.7 years) with medulloblastoma. All tumors were histologically proved and were localizated infratentorially in the posterior fossa. All of the patients were irradiated with a dose of 24-36 Gy to the whole craniospinal axis and boost with conformal therapy restricted to the tumor bed to the total dose of 50-54 Gy (30-36 Gy "high risk", 24-30 Gy "standard risk" group). Chemotherapy received 26 patients (78%). Patients with craniospinal irradiation were placed in supine position and fixed by a vacuum-form body immobilizer and head mask. Irradiation was performed using standard fractionation (5 fractions per week) with a single dose of 1.5-1.8 Gy for craniospinal axis by photon beam (6 MV) of the linear accelerator. The median overall survival for the whole group was 55.3 months. The median of disease-free survival was 20.6 months, 8 patients (24%) died. In our study the statistical difference in survival rate between standard and high-risk patients with medulloblastoma was not shown. No relationship was found between survival and age, sex or tumor size. Endocrine deficits occurred in 45% (8 patients of the group were hypothyroid, 6 patients needed growth hormone replacement therapy, 1 patient had early puberty). This results (results of overall and disease-free survival) and side-effects of technique of craniospinal axis irradiation in supine position are comparable with results of technique in prone position. Further evaluation of the effectiveness of our therapy is not feasible due to the small number of patients.