Analysis of risk and predictors of brain radiation necrosis after radiosurgery
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Hongqing Zhuang1, Yi Zheng2, Junjie Wang3, Joe Y. Chang4, Xiaoguang Wang1, Zhiyong Yuan1, Ping Wang1
1Department of Radiotherapy, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin Key Laboratory of Cancer Prevention and Therapy and Tianjin Lung Cancer Center, Tianjin, China
2Daqing Oilfield General Hospital, Heilongjiang, China
3Department of Radiotherapy, Peking University 3rd Hospital, Beijing, China
4Department of Radiation Oncology, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
Zhiyong Yuan, e-mail: [email protected]
Keywords: brain radiation necrosis, Cyberknife, stereotactic radiotherapy (SRT), biologically equivalent dose (BED)
Received: August 19, 2015 Accepted: November 25, 2015 Published: December 10, 2015
In this study, we examined the factors contributing to brain radiation necrosis and its predictors of patients treated with Cyberknife radiosurgery. A total of 94 patients with primary or metastatic brain tumours having been treated with Cyberknife radiotherapy from Sep. 2006 to Oct. 2011 were collected and retrospectively analyzed. Skull based tracking was used to deliver radiation to 104 target sites. and the prescribed radiation doses ranged from 1200 to 4500 cGy in 1 to 8 fractions with a 60% to 87% isodose line. Radiation necrosis was confirmed by imaging or pathological examination. Associations between cerebral radiation necrosis and factors including diabetes, cardio-cerebrovascular disease, target volume, isodose line, prescribed dosage, number of fractions, combination with whole brain radiation and biologically equivalent dose (BED) were determined by logistic regression. ROC curves were created to measure the predictive accuracy of influence factors and identify the threshold for brain radiation necrosis. Our results showed that radiation necrosis occurred in 12 targets (11.54%). Brain radiation necrosis was associated by BED, combination with whole brain radiotherapy, and fractions (areas under the ROC curves = 0.892±0.0335, 0.650±0.0717, and 0.712±0.0637 respectively). Among these factors, only BED had the capability to predict brain radiation necrosis, and the threshold dose was 7410 cGy. In conclusion, BED is the most effective predictor of brain radiation necrosis, with a dose of 7410 cGy being identified as the threshold.
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