Dose-volume prediction of radiation-related complications after hypofractionated conformal radiotherapy for brain metastases in critical areas

Abstract

The use of hypofractionated radiotherapy to treat brain metastases and other lesions in critical areas demands an accurate understanding of the risks of complication. We therefore analyzed risk factors for predicting complications after hypofractionation treatment (two to 10 fractions) for brain metastases based on data for 470 lesions in 367 patients treated with conformal radiotherapy using the CyberKnife. Twenty-seven lesions in 24 patients exhibited complications over a median follow-up period of seven months (2-50 months). The tumor and brain volumes circumscribed with a single dose equivalent (SDE) of 14 Gy (V14) were found to be significant factors of complications in a univariate analysis. However, the V14 was the only significant factor in the multivariate analysis. Other risk factors were analyzed based on differences between the groups in the characteristics of the 27 lesions. Consequently, the tumor location (cerebrum, p=0.003), tumor volume (≥ 10cm 3 , p=0.01), SDE of the maximum dose (≥ 40 Gy, p=0.01), and V14 (≥ 3cm 3 , p=0.001) were identified to be significant predictive factors according to the t-test, while the marginal dose (≥ 31 Gy) and fraction number (≤ five) were found to be borderline significant. The actual risk of complications after hypofractionated conformal radiotherapy can be best predicted using a model that accounted for the SDE of the maximum dose and V14.