Intraoperative vs Hypofractionated Stereotactic Radiotherapy Post-Brain Metastasis Surgery

Overview

This retrospective study compared intraoperative radiotherapy (IORT) and hypofractionated stereotactic radiotherapy (HSRT) following brain metastasis resection. Both modalities showed comparable local control and overall survival, but IORT demonstrated a significantly lower incidence of radionecrosis and reduced delay to radiation initiation.

Background

Surgical resection is effective for symptomatic or large brain metastases but carries high local recurrence without adjuvant therapy. Whole brain irradiation has declined due to neurocognitive toxicity, with stereotactic radiotherapy becoming the standard for post-resection cavity treatment. IORT offers immediate radiation delivery during surgery, potentially reducing treatment delays and improving target accuracy. With prolonged survival in stage IV malignancies, optimizing local control while minimizing toxicity is critical.

Data Highlights

Key Findings

• Both IORT and HSRT cohorts had similar median age and baseline characteristics, including metastasis size and RPA classification.
• IORT was delivered intraoperatively, eliminating the median 29-day delay seen with HSRT initiation.
• The biologically effective dose at the planning target volume margin was comparable between IORT (50 Gy) and HSRT (48 Gy).
• IORT was associated with a significantly lower one-year incidence of radionecrosis (3.7%) compared to HSRT (21.8%).
• Operation room time was modestly increased by 25 minutes in the IORT group due to radiation delivery during surgery.
• Histological distribution differed slightly, with more breast cancer cases in HSRT and more NSCLC in IORT, but this did not significantly impact outcomes.

Clinical Implications

IORT offers the advantage of immediate radiation delivery during surgery, reducing treatment delays and potentially improving patient convenience. The significantly lower radionecrosis rates with IORT suggest a favorable toxicity profile, which is important given the prolonged survival of patients with brain metastases. Clinicians should consider IORT as a viable alternative to HSRT for suitable patients, balancing operative time and resource availability.

Conclusion

IORT and HSRT provide comparable oncological outcomes following brain metastasis resection, but IORT significantly reduces radionecrosis incidence and eliminates delays to radiation initiation. These findings support the integration of IORT into multidisciplinary treatment strategies for brain metastases.

References

1. Patel et al. 2023 -- Evaluating Intraoperative Radiotherapy versus Hypofractionated Stereotactic Radiotherapy Following Brain Metastasis Surgery