Intraoperative Radiotherapy for Malignant Intrinsic Brain Tumors: A Single-center Retrospective Study

Introduction: For most of the malignant intrinsic brain tumors, nearly all the tumors recur locally, suggesting that augmenting local treatments may improve outcomes. As an adjuvant option to surgery, intraoperative radiotherapy (IORT) is gaining increasing attention in the treatment of malignant intrinsic tumors. This study investigates whether intraoperative radiotherapy (IORT) for the resection cavity is safe and effective.

Methods: In total, 42 patients with 43 intrinsic brain tumors were included in the analysis (21 cases with 21 lesions in the surgery group and 21 cases with 22 lesions in the surgery + IORT group). The technical-related complications, radiation-related complications, progression-free survival (PFS), and overall survival (OS) after the surgery were recorded and analyzed.

Results: In the surgery-only group, there were 10 metastatic tumors (MTs) and 11 high-grade gliomas (HGGs). In the surgery+IORT group, there were 9 cases of MTs, 11 cases (12 lesions) of HGGs, and one lymphoma. In this group, one case suffered from a frontal and an occipital lesion. Both lesions were histologically confirmed to be glioblastoma. This patient got two-stage surgery for the removal of the two lesions respectively and got IORT twice. The median IORT dose is 18Gy (low-energy photon beam). The median PFS was 7.2 months (95% CI: 6.3–10.5) and 11 months (95% CI: 9.3–14.6) for those patients who received surgery and surgery + IORT, respectively. Patients in the surgery + IORT group also had a longer OS (12.8 months, 95% CI: 11.4–17.2) than those in the surgery group (9.3 months, 95% CI: 8.9–12.9). The Kaplan–Meier survival curves, analyzed by log-rank test, revealed a statistically significant difference in PFS and OS between both groups. This suggests that IORT is active in the observed benefits for PFS and OS. No radiation-related complications were observed in the IORT group.

Conclusion : This study suggests that low-dose IORT may improve the prognosis of intrinsic brain tumor patients. Future prospective large-scale studies are needed to validate the efficacy and safety of IORT.