Determinants of Local Recurrence After Stereotactic Radiation in Single Breast Cancer Brain Metastasis

Overview

This retrospective study evaluated factors influencing local recurrence following stereotactic radiation treatment (SRT) to the surgical cavity in patients with a single brain metastasis from breast cancer. Key determinants included tumor biology, radiation dose parameters, and clinical variables. The findings highlight the importance of breast cancer subtype and radiation dosing in optimizing local control.

Background

Brain metastases from breast cancer (BCBM) are increasingly common due to improved systemic disease control and prolonged survival. Local therapy has shifted from whole brain radiation therapy (WBRT) to stereotactic radiation (SRT) to minimize toxicity while maintaining local control. However, local failure rates remain a concern, especially after surgery alone. Breast cancer molecular subtypes and radiation dose/fractionation have been suggested as important factors influencing local control after SRT.

Data Highlights

Key Findings

• Local control after SRT is influenced by breast cancer molecular subtype, with HER2-positive and triple negative subtypes being predominant in the cohort.
• Radiation dose parameters, including biological effective dose (BED) and fractionation, correlate with local recurrence risk.
• Systemic therapy use and timing relative to radiation may impact intracranial disease control.
• Local failure was defined radiographically within the surgical cavity and confirmed by tumor board consensus.
• Most patients had favorable prognostic scores (DS-GPA 2.5–4), indicating relatively good expected survival.
• Receptor status conversion between primary tumor and brain metastasis occurred in a minority of patients, suggesting tumor biology evolution.

Clinical Implications

Clinicians should consider breast cancer subtype and radiation dosing strategies when planning postoperative SRT for brain metastases to optimize local control. Multidisciplinary tumor board discussions remain essential to tailor treatment plans. Awareness of receptor status changes may guide systemic therapy decisions in the metastatic setting.

Conclusion

Local recurrence following SRT in single breast cancer brain metastasis is multifactorial, with tumor biology and radiation parameters playing key roles. Personalized treatment approaches based on these determinants may improve intracranial disease control.

References

1. Sperduto et al. 2017 -- Prognosis and local therapy trends in breast cancer brain metastases
2. Grubb et al. -- Breast cancer molecular subtype as predictor for local control after SRT
3. Society of Neuro-Oncology and International SRT Guidelines