Analysis of risk and predictors of brain radiation necrosis after radiosurgery. Zhuang Hongqing,Zheng Yi,Wang Junjie,Chang Joe Y,Wang Xiaoguang,Yuan Zhiyong,Wang Ping Oncotarget 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. 10.18632/oncotarget.6532

Dosimetric predictors of symptomatic radiation necrosis after five-fraction radiosurgery for brain metastases. Andruska Neal,Kennedy William R,Bonestroo Liberty,Anderson Rebecca,Huang Yi,Robinson Clifford G,Abraham Christopher,Tsien Christina,Knutson Nels,Rich Keith M,Spencer Christopher,Huang Jiayi Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology BACKGROUND:To identify factors predictive of developing symptomatic radiation necrosis (sRN) among patients with either intact or resected brain metastases undergoing five-fraction stereotactic radiosurgery (5fSRS). METHODS:Multi-institutional retrospective review of 117 brain metastases from 83 patients treated with 5fSRS. The cumulative incidence of sRN and predictors of sRN were calculated using Gray's competing risks and Cox regression. RESULTS:The median dose of 5fSRS was 30 Gy (range: 25-40), and 21 lesions (18%) had prior SRS. After a median follow-up of 10.3 months (range: 3-52), the cumulative sRN incidence was 15%, with a median time to sRN of 6.9 months (range: 1.8-31.7). sRN incidence was significantly higher among the lesions treated with prior SRS: hazard ratio (HR): 7.48 [95% confidence interval: 2.57-21.8]. Among lesions without prior SRS, higher volume of uninvolved brain receiving 25 Gy (BrainV25; HR: 1.07 [1.02-1.12]) and 30 Gy (BrainV30; HR: 1.07 [1.01-1.33]) were the most significant factors associated with sRN. Similar results were also observed among the patients with prior SRS. For lesions without prior SRS, BrainV25 > 16 cm (HR: 11.7 [1.47-93.3]) and BrainV30 > 10 cm (HR: 7.08 [1.52-33.0]) were associated with significantly higher risk of sRN. At two years, the sRN incidence was 21% if violating either dosimetric threshold and 2% if violating neither (p = .007). CONCLUSION:BrainV25 and BrainV30 are significant dosimetric predictors of sRN of brain metastases treated with 5fSRS. In the absence of prior SRS, maintaining BrainV25Gy < 16 cm and BrainV30Gy < 10 cm may minimize sRN risk. 10.1016/j.radonc.2020.12.011