Abstract 2825: Investigation of sponge property for enhanced concurrent tumor treating fields and radiotherapy for glioblastoma
Authors: Zheng Jiajun , Zhu Huanfeng , Guo Wenjie , Guo Jiahao , Cao Chechen , Sun Li , Xu Geng , Wang Zhi , Dai Baoying , Gu Ning , He Xia 
Published: April 2023

Abstract
Glioblastoma (GBM) is an aggressive primary brain tumor in adults featured with low overall survival (OS) of around 10-16 months, which is estimated to cause about 200,000 deaths related to the tumors of central nervous systems every year. Therefore, precise therapy on newly diagnosed GBM and increase median OS through concurrent tumor treating fields (TTFields) and chemoradiotherapy (the standard-of-care treatment proposed by NCCN) is of great significance. Though introducing latex-free sponge media was reported beneficial for improving concurrent TTFields and chemoradiotherapy efficacy on GBM, the specific enhancement mechanism and physical/chemical parameters of sponge media has not been studied as far as we know. Herein, different latex-free polyurethane sponges were selected based on SPARE phase II clinical research to investigate their impact on the concurrent TTFields and chemoradiotherapy efficacy on GBM. As computed tomography (CT) imaging of tumor and radiation dose are two vital factors for radiotherapy, the Hounsfield unit (HU) values of sponges were tested under Micro-CT firstly and the results suggest that the sponges with HU value lower than -750 have almost no impact on CT image, and clearer CT image is obtained upon the sponge with lower HU value. Moreover, eight clinical IMRT/VMAT plans were selected randomly and delivered into the bare (as a reference) or each-of-samples-surrounded CIRS head phantom with built-in EBT film to evaluate dosimetry effect. Film-based Gamma Passing Rate (2%/2 mm criteria, 20% threshold) analysis indicates that all the dose distributions upon three sponges (99.55±0.23, 99.54±0.22 and 99.59±0.19, respectively) are in good consistence with that over the reference (99.31%~99.98%). Importantly, the enhancement mechanism of latex-free sponge on concurrent TTFields and radiotherapy efficacy was studied and it corroborated that the introduced sponge could reduce the artifacts of target delineation generated in the presence of transducer array, decrease the position error of transducer array movement/replacement on scalp, lower constrictive injury during TTFields therapy (especially for locating transducer array position upon CT imaging), and reduce the adverse event of TTFields including irritant or allergic contact dermatitis caused by transducer array in the period of radiotherapy. This work corroborates that introducing low-HU-value sponge media into concurrent TTFields and chemoradiotherapy for GBM is a promising strategy to enhance therapy efficacy and thus improve or maintain the quality of patients’ life.
Citation Format: Jiajun Zheng, Huanfeng Zhu, Wenjie Guo, Jiahao Guo, Chechen Cao, Li Sun, Geng Xu, Zhi Wang, Baoying Dai, Ning Gu, Xia He. Investigation of sponge property for enhanced concurrent tumor treating fields and radiotherapy for glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2825.