Reports of Practical Oncology and Radiotherapy最新文献

Background and objectives: Despite decades of experience with definitive chemo-radiotherapy (CRT) in cervical oesophageal cancer (CEC), the loco-regional control and survival outcomes are dismal. This review evaluated the outcomes of various treatment strategies being commonly utilized.

Materials and methods: A literature review was conducted to identify relevant articles on CEC published from years 2000-2023 addressing the predefined key questions. These questions focussed on the comparative outcomes of various primary treatment approaches (surgery, CRT, or trimodality treatment) and the radiation dose schedules, volumes, and techniques.

Results: CRT is the standard approach for treatment for CEC so far. The potential role of surgery and trimodality approach in settings of evolving surgical approaches needs to be validated. The high dose schedules that are preferentially practiced in CEC have not shown any benefit in improving the disease outcomes over the standard dose schedule of 50.4 Gy. The target volume delineation practice of elective nodal irradiation (ENI) does not have a proven benefit over the involved field irradiation (IFI). The limited evidence on radiation techniques suggests that intensity-modulated radiotherapy/volumetric-modulated arc therapy (IMRT/VMAT) techniques can improve toxicity profile over three-dimensional conformal radiotherapy (3DCRT), but no advantage proven in disease outcomes so far.

Conclusion: This review will guide clinicians in decision-making for the management of this relatively rare entity and the directions for future research in these areas. Future large-scale multicentre prospective studies are needed for validating and standardizing our current practices and exploring potential options to improve the outcomes.

Background: The purpose was to analyse the interrelations between planning and complexity metrics and gamma passing rates (GPRs) obtained from VMAT treatments and build the forecasting models for qualitative prediction (QD) of GPRs results.

Materials and method: 802 treatment arcs from the plans prepared for the head and neck, thorax, abdomen, and pelvic cancers were analysed. The plans were verified by portal dosimetry and analysed twice using the gamma method with 3%|2mm and 2%|2mm acceptance criteria. The tolerance limit of GPR was 95%. Red, yellow, and green QDs were established for GPR examination. The interrelations were examined, as well as the analysis of effective differentiation of QD. Three models for QD forecasting based on discriminant analysis (DA), random decision forest (RDF) methods, and the hybrid model (HM) were built and evaluated.

Results: Most of the interrelations were small or moderate. The exception is correlations of the join function with the average number of monitor units per control point (R = 0.893) and the beam aperture with planning target volume (R = 0.897). While many metrics allow for the effective separation of the QDs from each other, the study shows that predicting the values of the QD is possible only through multi-component forecasting models, of which the HM is the most accurate (0.894).

Conclusion: Of the three models explored in this study, the HM, which uses DA methods to predict red QD and RDF methods to predict green and yellow QDs, is the most promising one.

Background: Simultaneous involvement of multiple distinct brain regions occurs in 2-5% of all high-grade gliomas (HGG) and is associated with poor prognosis. Whereas radiotherapy (RT) is an important and well-established treatment for high-grade glioma, the role of dose-escalated radiotherapy has yet to be established. In this case series, we report upon the dosimetry, adverse effects, and response in patients with multiple un-methylated high-grade gliomas receiving dose-escalated radiation.

Materials and methods: We reviewed charts of patients with multifocal high grade glioma treated at our institution since January 2022. All patients had stereotactic biopsies after an magnetic resonance imaging (MRI) contrast-enhanced with T1, T2, FLAIR sequences and were discussed in a multidisciplinary oncology team. MGMT-positive patients received either TMZ alone or RT with TMZ and were excluded from this analysis. Un-methylated patients received dose-escalated RT without temezolamide (TMZ). Following computed tomography (CT) and MR simulation, the gros tumor volume (GTV) was delineated and prescribed 52.5 Gy in 15 fractions within the standard 40.05 Gy planning treatment volume (PTV). Treatment planning was volumetric modulated arc therapy.

Results: A total of 20 patients with multiple un-methylated MGMT glioblastoma multiforme were treated with dose-escalated radiation therapy between January 2022 and June 2023. All patients completed dose escalated radiotherapy without acute adverse effects. Progression-free survival at six months was 85%, as defined by the RANO criteria.

Conclusion: In this case series, we showed that un-methylated multiple high-grade glioma could be safely treated with dose escalation. Results of progression-free survival should be validated in a larger prospective clinical trial.

Background: Task Group 43 (TG-43) formalism does not consider the tissue and applicator heterogeneities. This study is to compare the effect of model-based dose calculation algorithms, like Advanced Collapsed Cone Engine (ACE), on dose calculation with the TG-43 dose calculation formalism in patients with cervical carcinoma.

Materials and methods: 20 patients of cervical carcinoma treated with a high dose rate of intracavitary brachytherapy were prospectively studied. The target volume and organs at risk (OARs) were contoured in the Oncentra treatment planning system (Elekta, Veenendaal, The Netherlands). All patients were planned with cobalt-60 (Co-60) and iridium-192 (Ir-192) sources with doses of 21 Gy in 3 fractions. These plans were calculated with TG-43 formalism and a model-based dose calculation algorithm ACE. The dosimetric parameters of TG-43 and ACE-based plans were compared in terms of target coverage and OAR doses.

Results: For Co-60-based plans, the percentage differences in the D90 and V100 values for high-risk clinical target volume (HR-CTV) were 0.36 ± 0.43% and 0.17 ± 0.31%, respectively. For the bladder, rectum and sigmoid, the percentage differences for D2cc volumes were -0.50 ± 0.51%, -0.16 ± 0.53% and -0.37 ± 1.21%, respectively. For Ir-192-based plans, the percentage difference in the D90 for HR-CTV was 0.54 ± 0.79%, while V100 was 0.24 ± 0.29%. For the bladder, rectum and sigmoid, the doses to 2cc volume were 0.35 ± 1.06%, 0.99 ± 0.74% and 0.74 ± 1.92%, respectively. No significant differences were found in the dosimetric parameters calculated with ACE and TG-43.

Conclusion: The ACE algorithm reduced doses to OARs and targets. However, ACE and TG-43 did not show significant differences in the dosimetric parameters of the target and OARs with both sources.

Background: The objective was to enhance the biological compensation factor related to irradiation interruption in a short time (short irradiation interruption) in hypoxic tumors using a refined microdosimetric kinetic model (MKM) for photon radiation therapy.

Materials and methods: The biological dose differences were calculated for CHO-K1 cells exposed to a photon beam, considering interruptions of (τ) of 0-120 min and pO₂ at oxygen levels of 0.075-160 mm Hg. The interrupted dose fraction (IDF) was defined as the percentage ratio of the dose delivered before short irradiation interruption to the total dose, which ranged from 10-90%. The compensated dose was calculated based on an IDF of 10-90% for a dose of 2-8 Gy and oxygen levels of 0.075-160 mm Hg.

Results: The Δ with and without short irradiation interruption was more pronounced with a higher dose and increased pO₂. It exceeded 3% between IDF of 50% and either 10% or 90% and occurred more than τ = 50 min at 0.075 mm Hg, τ = 20 min at 3 mm Hg, τ = 20 min at 8 mm Hg, τ = 20 min at 15 mm Hg, τ = 20 min at 38 mm Hg, and τ = 20 min at 160 mm Hg. The dose compensation factor was greater at higher IDF rates.

Conclusion: The biological dose decreased with longer interruption times and higher oxygen concentrations. The improved model can compensate for the biological doses at various oxygen concentrations.

Advances in knowledge: The current study improved the dose compensation method for the decrease in the biological effect owing to short irradiation interruption by considering the oxygen concentration.

Background: EBT-XD film specially designed for high dose verifications such as stereotactic treatments. The dose response of the film can be affected by several factors, the curly nature of the film being one of them. In this study this curly nature of the film was investigated for stereotactic body radiotherapy (SBRT) plan verifications.

Materials and methods: For this study, 18 SBRT (11 prostate, 3 spines, and 4 lungs) cases were enrolled. For all the cases, VMAT plans were created in the Monaco treatment planning system and plan was delivered in Elekta Versa HD linear accelerator and delivered fluence was captured by EBT-XD films. All films were scanned with and without a compression plate. All the films were analyzed using the single-channel film method using the red channel.

Results: A significant difference in the gamma passing rates (GPR) for the films scanned with and without the compression plate was observed. The maximum percentage differences in GPR between using and not using a compression plate were 12.7% for 1% 1 mm, 8.1% for 2% 2 mm, 7.5% for 3% 2 mm, and 5% for 3% 3mm criteria. Similarly, the mean %difference in GPR was 5.8% for 1% 1 mm, 2.4% for 2% 2 mm, 1.6% for 3% 2 mm and 0.96% for 3% 3 mm criteria.

Conclusion: The results suggest that placing a compression plate over the film during scanning provided a great advantage in achieving a more accurate gamma passing rate irrespective of gamma criteria.

Background: Diffuse intrinsic pontine glioma (DIPG) stands as the predominant type of brainstem glioma. It is characterized by a notably brief median survival period, with the majority of patients experiencing disease progression within six months following radiation therapy. This systematic review and meta-analysis aims to assess the efficacy and safety of hypofractionated radiotherapy (HFRT) compared to conventionally fractionated radiotherapy (CFRT) in DIPG treatment.

Materials and methods: A systematic literature search was conducted in four databases, and relevant studies comparing HFRT and CFRT in DIPG were included. Data were extracted and analyzed for overall survival (OS), progression-free survival (PFS), and treatment-related toxicities. Statistical analysis was performed using random-effects models with heterogeneity assessment.

Results: Five studies met the inclusion criteria, comprising 518 patients. No significant difference in one-year OS was observed between HFRT and CFRT (29% vs. 22%, p = 0.94). The median OS was similar in both treatment groups (9.7 vs. 9.3 months, p = 0.324). Similarly, no significant difference in one-year PFS was found between HFRT and CFRT (19.8% vs. 16.6%, p = 0.82), with comparable median PFS (9.3 vs. 9.4 months, p = 0.20). In meta-regression analysis, there was no association of chemotherapy (p > 0.05) or radiation biologically effective dose (BED) (p > 0.05) regarding OS or PFS outcomes. There were no significant differences in treatment-related toxicities.

Conclusions: HFRT yields one-year OS and PFS rates similar to CFRT in DIPG, with no significant differences in treatment-related toxicities. Chemotherapy and BED did not affect OS or PFS.

Worldwide increase of head and neck cancers ranks these malignancies among top causes of cancer in human population. Radiation induced skin injury (RISI) is one of the major side effects of radiotherapy (RT). Skin of the neck is exposed to radiation due to necessity of therapeutic or prophylactic (elective) irradiation of neck lymph nodes and target organs, including the larynx and hypopharynx. The location of the neck exposes these regions of the skin to various additional exposomes such as ultraviolet radiation (UVR), pollution and cigarette smoke. There are many controversies or inconsistencies regarding RISI, from molecular aspects and therapy to terminology. There is lack of high-quality and large-sample studies in both forms of RISI: acute (aRISI) and chronic (cRISI). Finally, no gold standards in the management of aRISI and cRISI have been established yet. In this article, the authors discuss the pathogenesis, clinical picture, prevention and clinical interventions and present a proposed treatment algorithm.

A high-energy electron accelerator is used in the treatment of patients in the so-called intraoperative electron radiotherapy (IOERT). The work aimed to present the results of the validation of a new design of an electron beam applicator for use in IOERT. A novel solution was described along with the design optimization method based on Monte Carlo simulations. In this solution, the applicator consists of two parts. The lower exchangeable part collimates the therapeutic field. Measurements were made based on the International Electrotechnical Commission (IEC) standard recommendations. The measurement described in the standard has been adapted to the specificity of the intraoperative accelerator Source to Skin Distance - of 60 cm and applicators with a circular cross-sectional area. Measurements were performed for nominal beam energies of 6, 10, and 12 MeV and two therapeutic field diameters of 6 and 10 cm. The dose due to stray X-ray radiation in all energies is less than 0.3% and increases for energies from 6 to 12 MeV by 2.9 times from 0.1 for 6MeV to 0.29 for 12 MeV. The average dose due to leakage radiation also shows an increasing trend and is higher for a 6 cm diameter applicator. Validation confirmed the usefulness of the novel applicator design for clinical applications. Thanks to the use of 3D printing, it was possible to make applicators that are transparent, biocompatible and, at the same time, light and form a beam field with therapeutically useful accuracy, and the leakage radiation does not exceed normative recommendations.