Cumulative volumetric analysis as a key criterion for the treatment of brain metastases

Recent studies have demonstrated diminished cognitive function, worse quality of life, and no overall survival benefit from the addition of adjuvant whole brain radiation therapy (WBRT) to stereotactic radiosurgery (SRS) in the management of brain metastases. This study analyzes the treatment outcome of SRS, specifically CyberKnife Radiosurgery, based on the total tumor volume compared to the absolute number of lesions.

A retrospective analysis of hospital records at Virginia Hospital Center for patients with brain metastases who underwent CyberKnife Radiosurgery between June 2008 and June 2014 was performed. Previous treatment history, metastatic tumor dimensions, and outcomes were recorded. Predictors of neurological defects, local tumor progression, and overall survival were assessed with univariate and multivariate analysis.

We identified 130 adult patients with a median age of 61.5years and a median follow-up of 7.1months. Unfavorable outcomes such as death, tumor progression, or neurological defect showed correlation with cumulative tumor volume greater than the median volume of 7cc (p<0.05). Worsening neurological defects showed an association with an increased number of lesions (p<0.02) and age (p<0.05). For local tumor progression, patients who have received WBRT were less likely to progress (.74, 95% CI, .48, 1.10), while those who received chemotherapy (1.48 95% CI, .98, 2.26), or surgery (1.56 95%, CI .98, 2.47) without WBRT were more likely to progress.

Our data suggest that a cumulative tumor volume greater than 7cc correlates with worse outcomes following CyberKnife Radiosurgery. In addition, WBRT appears to have a role in improved survival for patients with increased tumor burden. A prospective study is warranted to validate these findings.