Objective:To evaluate the acute toxicities and related influencing factors of vertebral-body-sparing proton craniospinal irradiation (VBSpCSI) using pencil beam scanning (PBS) technology in pediatric patients, and to assess spinal growth and survival outcomes.Methods:A retrospective analysis was conducted on 70 pediatric patients treated with PBS-based VBSpCSI at Hebei Yizhou Cancer Hospital between January 2020 and December 2022, and continued to follow up until November 2023. Acute toxicities were assessed, and linear regression analysis combined with receiver operating characteristic curve were employed to investigate the dose-effect relationship between vertebral dose and toxicities. Spinal growth after radiotherapy was evaluated by measuring the Cobb angle on follow-up MRI. Overall survival (OS) and progression-free survival (PFS) were estimated using the Kaplan-Meier method.Results:The median age of patients at the time of irradiation was 6 years (range, 2-16 years). Two patients (3%) developed grade ≥3 gastrointestinal toxicities, while 7 patients (10%) experienced grade 1 radiation-induced esophagitis. The nadirs of white blood cell count (WBC), absolute neutrophil count (ANC), and absolute lymphocyte count (ALC) during treatment were significantly negatively correlated with vertebral V 5 Gy ( P=0.009, 0.006, 0.001) and vertebral V 20 Gy ( P=0.007, 0.011, <0.001). When vertebral V 5 Gy<86.5% and vertebral V 20 Gy<73.2%, the incidence of grade ≥3 myelosuppression was significantly reduced ( P<0.001, =0.001). Additionally, younger patient age (in months) and concurrent chemotherapy were also significantly associated with increased acute hematologic toxicity. Among 43 patients with MRI follow-up, no scoliosis, kyphosis, or chronic lumbosacral pain was observed. The 3-year OS and PFS rates were 95.7% and 86.4%, respectively. Conclusions:PBS-based VBSpCSI in pediatric patients demonstrates manageable acute toxicities, with a clear dose-effect relationship between vertebral V 5 Gy , V 20 Gy and hematologic toxicities, and the incidence of non-hematological toxicities remains low. No adverse effects on spinal growth or survival outcomes were observed in the short term.

Objective:To evaluate the acute toxicities and related influencing factors of vertebral-body-sparing proton craniospinal irradiation (VBSpCSI) using pencil beam scanning (PBS) technology in pediatric patients, and to assess spinal growth and survival outcomes.Methods:A retrospective analysis was conducted on 70 pediatric patients treated with PBS-based VBSpCSI at Hebei Yizhou Cancer Hospital between January 2020 and December 2022, and continued to follow up until November 2023. Acute toxicities were assessed, and linear regression analysis combined with receiver operating characteristic curve were employed to investigate the dose-effect relationship between vertebral dose and toxicities. Spinal growth after radiotherapy was evaluated by measuring the Cobb angle on follow-up MRI. Overall survival (OS) and progression-free survival (PFS) were estimated using the Kaplan-Meier method.Results:The median age of patients at the time of irradiation was 6 years (range, 2-16 years). Two patients (3%) developed grade ≥3 gastrointestinal toxicities, while 7 patients (10%) experienced grade 1 radiation-induced esophagitis. The nadirs of white blood cell count (WBC), absolute neutrophil count (ANC), and absolute lymphocyte count (ALC) during treatment were significantly negatively correlated with vertebral V 5 Gy ( P=0.009, 0.006, 0.001) and vertebral V 20 Gy ( P=0.007, 0.011, <0.001). When vertebral V 5 Gy<86.5% and vertebral V 20 Gy<73.2%, the incidence of grade ≥3 myelosuppression was significantly reduced ( P<0.001, =0.001). Additionally, younger patient age (in months) and concurrent chemotherapy were also significantly associated with increased acute hematologic toxicity. Among 43 patients with MRI follow-up, no scoliosis, kyphosis, or chronic lumbosacral pain was observed. The 3-year OS and PFS rates were 95.7% and 86.4%, respectively. Conclusions:PBS-based VBSpCSI in pediatric patients demonstrates manageable acute toxicities, with a clear dose-effect relationship between vertebral V 5 Gy , V 20 Gy and hematologic toxicities, and the incidence of non-hematological toxicities remains low. No adverse effects on spinal growth or survival outcomes were observed in the short term.