Oncological Outcomes After Intraoperative Radiotherapy for Brain Metastases Resection

Overview

This single-center cohort analysis of 117 brain metastases treated with intraoperative radiotherapy (IORT) following neurosurgical resection demonstrates a high local control rate of 90.5% and a median overall survival of 18.2 months. The study highlights IORT as an effective focal radiotherapy modality with favorable oncological outcomes and manageable toxicity in a routine clinical setting.

Background

Surgical resection is the preferred treatment for large and symptomatic brain metastases, but surgery alone results in high local recurrence rates, necessitating additional radiotherapy. Whole brain irradiation has largely been replaced by focal radiotherapy of the resection cavity to reduce neurotoxicity. Intraoperative radiotherapy (IORT) using 50 kV x-rays offers advantages over stereotactic radiotherapy, including steeper dose gradients, higher relative biological efficacy, and immediate treatment post-resection, potentially improving local control and modulating antitumor immune responses.

Data Highlights

Key Findings

• Median overall survival was 18.2 months with a 1-year survival rate of 57.7%.
• Local control of the resection cavity was high at 90.5%, with an estimated 1-year local control of 84.2%.
• Distant brain control was lower, with an observed rate of 61.9% and an estimated 1-year rate of 47.9%.
• Leptomeningeal disease developed in 5.7% of patients, with an estimated 1-year incidence of 10.4%.
• The predominant histology treated was non-small-cell lung cancer, followed by malignant melanoma and breast carcinoma.
• IORT was well tolerated and allowed immediate postoperative radiotherapy, potentially reducing the interval-related risk of recurrence.

Clinical Implications

IORT after neurosurgical resection of brain metastases provides effective local control with a favorable safety profile, making it a valuable alternative to postoperative stereotactic radiotherapy. The immediate delivery of radiation during surgery may reduce local recurrence risk and limit radiation exposure to surrounding brain tissue, potentially decreasing neurotoxicity. Clinicians should consider IORT as part of a multidisciplinary approach for suitable patients with brain metastases requiring resection.

Conclusion

This large single-center cohort confirms that intraoperative radiotherapy is an effective and safe modality for improving local control after brain metastasis resection, with encouraging survival outcomes. IORT represents a promising focal radiotherapy technique that warrants further integration into routine neuro-oncological practice.

References

1. Kahl et al. 2023 -- Update on Oncological Outcomes Following Intraoperative Radiotherapy After Neurosurgical Resection of Brain Metastases