Evaluation of Intra-cavitary Radiotherapy Techniques for Resected Brain Metastases

Overview

This meta-analysis of 23 studies including 858 patients compares intraoperative radiotherapy (IORT) and intracavitary brachytherapy (IBT) following brain metastasis resection. Both techniques demonstrate high 1-year local control rates (85–96%) and favorable safety profiles, with reconstructed individual patient data enabling refined survival estimates and direct comparison.

Background

Brain metastases are the most common intracranial malignancy in adults, affecting up to 12.1% of metastatic cancer patients. Surgical resection is standard for accessible lesions, but residual microscopic disease often leads to high recurrence without adjuvant therapy. Traditional whole-brain radiotherapy improves local control but has limited survival benefit and risks neurocognitive decline, prompting interest in localized radiotherapy techniques such as IORT and IBT. These methods deliver radiation during or immediately after surgery, minimizing exposure to healthy brain tissue and treatment delays.

Data Highlights

Key Findings

• Both IORT and IBT provide high 1-year local control rates ranging from 85% to 96% after brain metastasis resection.
• Reconstructed individual patient data from Kaplan-Meier curves allowed refined survival analyses and direct comparison between IORT and IBT.
• Postoperative radiotherapy with IORT or IBT reduces the high recurrence rates (46–60%) seen without adjuvant treatment.
• Both techniques minimize radiation exposure to healthy brain tissue and reduce treatment delays compared to traditional whole-brain radiotherapy.
• Reported adverse events include radiation necrosis and leptomeningeal disease, but rates were generally low and manageable.
• Study quality varied, with prospective studies scoring higher; limitations include non-randomization and heterogeneity among cohorts.

Clinical Implications

IORT and IBT represent effective localized radiotherapy options following surgical resection of brain metastases, offering high local control while preserving cognitive function compared to whole-brain radiotherapy. Their intraoperative or immediate postoperative delivery reduces treatment delays and limits radiation exposure to normal brain tissue, supporting their integration into multidisciplinary management of brain metastases.

Conclusion

This comprehensive meta-analysis supports the efficacy and safety of intra-cavitary radiotherapy techniques, IORT and IBT, as valuable adjuvant treatments after brain metastasis resection. Further prospective randomized studies are warranted to optimize patient selection and compare long-term outcomes.

References

1. Nayak et al. 2012 -- Epidemiology of brain metastases
2. Patchell et al. 1990 -- Surgical resection and radiotherapy for brain metastases
3. Brown et al. 2016 -- Neurocognitive effects of whole-brain radiotherapy
4. Liu et al. 2021 -- Methodology for reconstructing individual patient data from KM curves
5. NIH Quality Assessment Tool 2023 -- Observational cohort study evaluation