The Advantage of Proton Therapy in Hypothalamic-Pituitary Axis and Hippocampus Avoidance for Children with Medulloblastoma

International Journal of Particle Therapy

卷:8

Saif Aljabab, MBBS, FRCPC¹  Lia M. Halasz, MD²  Shushan Rana, MD²  Phillip J. Taddei, PhD²  Jackie Castro, CMD³  Shadonna Maes, CMD³  Avril O’Ryan-Blair, CMD³  Jack Zheng, MD⁴ 

[1] 1 Radiation Oncology Department, King Saud University, Riyadh, Saudi Arabia;

[2] 2 Radiation Oncology Department, University of Washington School of Medicine, Seattle, WA, USA;

[3] 3 Seattle Cancer Care Alliance Proton Therapy Center, Seattle, WA, USA;

[4] 4 Radiation Medicine Program, the Ottawa Hospital Cancer Centre, Ottawa, ON, Canada;

关键词: craniospinal irradiation;    hippocampus avoidance;    pituitary avoidance;    impt;    vmat;    tomotherapy;   

DOI  :  10.14338/IJPT-21-00001.1

来源: DOAJ

【 摘 要 】

Purpose: Craniospinal irradiation (CSI) improves clinical outcomes at the cost of long-term neuroendocrine and cognitive sequelae. The purpose of this pilot study was to determine whether hypothalamic-pituitary axis (HPA) and hippocampus avoidance (HPA-HA) with intensity-modulated proton therapy (IMPT) can potentially reduce this morbidity compared with standard x-ray CSI.Materials and Methods: We retrospectively evaluated 10 patients with medulloblastoma (mean, 7 years; range, 4-14 years). Target volumes and organs at risk were delineated as per our local protocol and the ACNS0331 atlas. An experienced neuroradiologist verified the HPA and hippocampus contours. The primary objective was CSI and boost clinical target volume (CTV) covering 95% of the volume (D95) > 99% coverage with robustness. Described proton therapy doses in grays are prescribed using a biological effectiveness relative to photon therapy of 1.1. The combined prescribed dose in the boost target was 54 Gy. Secondary objectives included the HPA and hippocampus composite average dose (Dmean ≤ 18 Gy). For each patient, volumetric modulated arc radiotherapy (VMAT) and tomotherapy (TOMO) plans existed previously, and a new plan was generated with 3 cranial and 1 or 2 spinal beams for pencil-beam scanning delivery. Statistical comparison was performed with 1-way analysis of variance.Results: Compared with standard CSI, HPA-HA CSI had statistically significant decreases in the composite doses received by the HPA (32.2 versus 17.9 Gy; P < .001) and hippocampi (39.8 versus 22.8 Gy; P < .001). The composite HPA Dmean was lower in IMPT plans (17.9 Gy) compared with that of VMAT (21.8 Gy) and TOMO (21.2 Gy) plans (P = .05). Hippocampi composite Dmean was also lower in IMPT plans (21 Gy) compared with that of VMAT (27.5 Gy) and TOMO (27.2 Gy) plans (P = .02). The IMPT CTV D95 coverage was lower in IMPT plans (52.8 Gy) compared with that of VMAT (54.6 Gy) and TOMO (54.6 Gy) plans (P < .001) The spared mean volume was only 1.35% (19.8 cm3) of the whole-brain CTV volume (1476 cm3).Conclusion: We found that IMPT has the strong potential to reduce the dose to the HPA and hippocampus, compared with standard x-ray CSI while maintaining target coverage. A prospective clinical trial is required to establish the safety, efficacy, and toxicity of this novel CSI approach.

【 授权许可】

Unknown