Brain volume reduction after whole-brain radiotherapy: quantification and prognostic relevance

Area of Science:

• Oncology
• Radiotherapy
• Neurology

Background:

• Whole-brain radiotherapy (WBRT) combined with stereotactic radiosurgery (SRS) for brain metastases is debated due to potential neurotoxicity.
• Radiation-induced brain volume reduction is a suspected factor limiting WBRT benefits.

Purpose of the Study:

• To quantify brain volume reduction following WBRT in patients with brain metastases.
• To evaluate the prognostic significance of brain volume reduction for overall survival.

Main Methods:

• Brain volumes of 91 patients were measured post-WBRT and compared to baseline.
• Brain volume reduction rate was calculated and analyzed using univariate and multivariate Cox regression.
• Analysis included treatment-related and pretreatment factors, and recursive partitioning analysis (RPA) classes.

Main Results:

• Brain volume reduction rate was a significant predictor of overall survival (P < 0.001), alongside number of metastases and age.
• Patients with favorable prognoses (RPA classes 1-2) showed less brain volume decrease than those with poor prognoses (RPA class 3) (P = 0.001).
• No correlation was found between radiation dose and brain volume reduction rate (P = 0.147).

Conclusions:

• A smaller decrease in brain volume after WBRT independently predicts longer overall survival.
• Brain volume reduction rate is a significant prognostic factor in brain metastasis patients treated with WBRT.