Carbon-ion radiotherapy alone vs. standard dose photon radiation with carbon-ion radiotherapy boost for high-grade gliomas: a retrospective study

This study aimed to compare the survival outcome and side effects in patients with primary high-grade glioma (HGG) who received carbon ion radiotherapy (CIRT) alone or as a boost strategy after photon radiation (photon + CIRT_boost).

Thirty-four (34) patients with histologically confirmed HGG and received CIRT alone or Photon + CIRT_boost, with concurrent temozolomide between 2020.03–2023.08 in Wuwei Cancer Hospital & Institute, China were retrospectively reviewed. Overall survival (OS), progression-free survival (PFS), and acute and late toxicities were analyzed and compared.

Eight WHO grade 3 and 26 grade 4 patients were included in the analysis. The median PFS in the CIRT alone and Photon + CIRT_boost groups were 15 and 19 months respectively for all HGG cases, and 15 and 17.5 months respectively for grade 4 cases. The median OS in the CIRT alone and Photon + CIRT_boost groups were 28 and 31 months respectively for all HGG cases, and 21 and 19 months respectively for grade 4 cases. No significant difference in these survival outcomes was observed between the CIRT alone and Photon + CIRT_boost groups. Only grade 1 acute toxicities were observed in CIRT alone and Photon + CIRT_boost groups. CIRT alone group had a significantly lower ratio of acute toxicities compared to Photon + CIRT_boost (3/18 vs. 9/16, p = 0.03). No significant difference in late toxicities was observed.

Both CIRT alone and Photon + CIRT_boost with concurrent temozolomide are safe, without significant differences in PFS and OS in HGG patients. It is meaningful to explore whether dose escalation of CIRT_boost might improve survival outcomes of HGG patients in future randomized trials.