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Radiation therapy (RT) plays a fundamental role in the treatment of malignant and benign brain tumors. Current state-of-the-art photon- and proton-based RT combines more conformal dose distribution of target volumes and accurate dose delivery while limiting the adverse radiation effects. PubMed was systematically searched from from 2000 to October 2023 to identify studies reporting outcomes related to treatment of central nervous system (CNS)/skull base tumors with PT in adults. Several studies have demonstrated that proton therapy (PT) provides a reduced dose to healthy brain parenchyma compared with photon-based (xRT) radiation techniques. However, whether dosimetric advantages translate into superior clinical outcomes for different adult brain tumors remains an open question. This review aims at critically reviewing the recent studies on PT in adult patients with brain tumors, including glioma, meningiomas, and chordomas, to explore its potential benefits compared with xRT. [ABSTRACT FROM AUTHOR]

Purpose: To assess the dosimetric advantages of apertures in intracranial single fraction proton radiosurgery. Materials and methods: Six neuroma and 10 meningioma patients were investigated. For each patient, six plans were computed, with two spot spacing and three aperture settings (no apertures, 5 and 8 mm margin between aperture and clinical target volume [CTV]). All plans were optimized on the CTV with the same beam arrangement and the same single‐field robust optimization (2 mm setup errors, 3.5% range uncertainties). Robustness analysis was performed with 0.5 and 1.0 mm systematic setup errors and 3.5% range uncertainties. CTV coverage in the perturbed scenarios and healthy brain tissue sparing in the surrounding of the CTV were compared. Results: Meningiomas were larger and at a shallow depth than neuromas. In neuromas, spot spacing did not affect OAR doses or the robustness of CTV coverage and the apertures reduced brain dose without any significant impact on CTV robustness. In meningiomas, smaller spot spacing produced a reduction in brain V5Gy and improved robustness of CTV coverage; in addition, an 8 mm margin aperture reduced low and medium brain tissue doses without affecting robustness in the 0.5 mm perturbed scenario. A 5 mm margin aperture caused a reduction of plan robustness. Conclusion: The optimal use of apertures is a trade‐off between sparing of low and medium dose to the healthy brain and robustness of target coverage, also depending on size and depth of the lesion. [ABSTRACT FROM AUTHOR]

Purpose: To investigate MRI myelin water imaging (MWI) by multicomponent T2 relaxometry as a quantitative imaging biomarker for brain radiation‐induced changes and to compare it with DTI. Methods: Sixteen patients underwent fractionated proton therapy (PT) receiving dose to the healthy tissue because of direct or indirect (base skull tumors) irradiation. MWI was performed by a multi‐echo sequence with 32 equally spaced echoes (10‐320 ms). Decay data were processed to identify 3 T2 compartments: myelin water (Mw) below 40 ms, intra‐extracellular water (IEw) between 40 and 250 ms, and free water (CSFw) above 250 ms. Both MWI and DTI scans were acquired pre (pre)‐treatment and immediately at the end (end) of PT. After image registration, voxel‐wise difference maps, obtained by subtracting MWI and DTI pre from those acquired at the end of PT, were compared with the corresponding biological equivalent dose (BED). Results: Mw difference showed a positive correlation and IEw difference showed a negative correlation with BED considering end–pre changes (P <.01). The changes in CSFw were not significantly correlated with the delivered BED. The changes in DTI data, considering end–pre acquisitions, showed a positive correlation between fractional anisotropy and the delivered BED. Conclusion: MWI might detect early white matter radiation‐induced alterations, providing additional information to DTI, which might improve the understanding of the pathogenesis of the radiation damage. [ABSTRACT FROM AUTHOR]

Purpose: To investigate MRI myelin water imaging (MWI) by multicomponent T 2 relaxometry as a quantitative imaging biomarker for brain radiation-induced changes and to compare it with DTI., Methods: Sixteen patients underwent fractionated proton therapy (PT) receiving dose to the healthy tissue because of direct or indirect (base skull tumors) irradiation. MWI was performed by a multi-echo sequence with 32 equally spaced echoes (10-320 ms). Decay data were processed to identify 3 T 2 compartments: myelin water (Mw) below 40 ms, intra-extracellular water (IEw) between 40 and 250 ms, and free water (CSFw) above 250 ms. Both MWI and DTI scans were acquired pre (pre)-treatment and immediately at the end (end) of PT. After image registration, voxel-wise difference maps, obtained by subtracting MWI and DTI pre from those acquired at the end of PT, were compared with the corresponding biological equivalent dose (BED)., Results: Mw difference showed a positive correlation and IEw difference showed a negative correlation with BED considering end-pre changes (P < .01). The changes in CSFw were not significantly correlated with the delivered BED. The changes in DTI data, considering end-pre acquisitions, showed a positive correlation between fractional anisotropy and the delivered BED., Conclusion: MWI might detect early white matter radiation-induced alterations, providing additional information to DTI, which might improve the understanding of the pathogenesis of the radiation damage., (© 2021 International Society for Magnetic Resonance in Medicine.)

Aim: The present phase II study aimed to evaluate the tolerance and safety of Dixentil, a nutritional supplement based on zinc with the addition of prebiotics (galacto-oligosaccharides), tyndalized probiotics (Lactobacillus acidophilus and L. casei) and vitamins B1, B2 and B6, and nicotinamide), given as prophylaxis to patients undergoing pelvic radiotherapy and its efficacy in the prevention and reduction of radiation-related gastrointestinal disorders., Patients and Methods: Forty consecutive patients who were candidates for pelvic radiotherapy received Dixentil before starting and during radiotherapy. The primary end-point was to evaluate the safety and tolerance of Dixentil. Secondary end-points were incidence and severity of radiation-induced diarrhea and number of patients who discontinued radiotherapy because of diarrhea., Results: Radiation-induced enteritis occurred in 17 patients, grade I and grade II diarrhea was documented in 14 and 3 patients respectively; no grade III or IV diarrhea was observed. Radiotherapy was discontinued due to treatment-induced enteritis only in two patients for 6 days., Conclusion: Use of Dixentil is an easy, safe, and feasible approach to protect patients against the risk of radiation-induced diarrhea., (Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.)

Background/aim: Patients with prostate cancer treated with neoadjuvant androgen ablation experience less radiation-induced intestinal toxicity, mostly due to a reduction of the volume of normal tissue exposed to high radiation doses. We aimed to evaluate if the anti-androgenic drug leuprorelin itself exerts a protective effect on irradiated bowel., Materials and Methods: Female, intact and castrated male C57BL/6J mice underwent 12-Gy total body irradiation, with or without a three-month leuprorelin (0.054 mg/kg/month i.p.) pre-treatment. After 24-72 h, mice were sacrificed and intestinal segments collected for histological, immunohistochemical and molecular analyses., Results: Leuprorelin markedly reduced radiation-induced jejunal and colonic histological alterations in mice, increased the number of regenerating crypts vs. irradiation, and reduced radiation-induced nitrotyrosine immunoreactivity. Leuprorelin significantly reduced radiation-induced matrix metallo-proteinase-2 (Mmp2) and -13, collagen 1 and -3, transforming growth factor-beta (Tgfb), p53, interleukin 6 (Il6), and B-cell lymphoma 2 (Bcl2)-associated X protein (Bax) gene expressions, and nuclear factor-kappa B (NFκB) and TGFβ protein expression, and hampered radiation-induced BCL2 protein down-regulation., Conclusion: Leuprorelin protects mice from radiation-induced intestinal injury, likely through a reduction of tissue oxidative stress. These findings give a biological interpretation to clinical observations of improved intestinal tolerance in patients undergoing androgen ablation before RT., (Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.)