Department of Radiation Oncology, University of North Carolina, Chapel Hill, NC, USA.
Department of Radiation Oncology, Johns Hopkins University, Baltimore, MA, USA.
Med Phys. 2018 Oct;45(10):4754-4762. doi: 10.1002/mp.13121. Epub 2018 Aug 31.
To estimate the radiobiological parameters of three popular NTCP models, which describe the dose-response relations of carotid blowout syndrome (CBOS) after stereotactic body radiotherapy (SBRT). To evaluate the goodness-of-fit and the correlation of those models with CBOS.
The study included 61 patients with inoperable locally recurrent head and neck cancer treated with SBRT using CyberKnife (Accuray, Sunnyvale, CA) at the Department of Radiation Oncology, Hacettepe University, Ankara, Turkey between June 2007 and March 2011. The dose-volume histograms of the internal carotid were exported from the plans of all the patients. The follow-up results regarding the end point of carotid blowout syndrome were collected retrospectively. Initially, univariable analyses (Wilcoxon rank-sum or Chi-square tests) and a multivariate logistic regression analysis were performed between the outcome data and a list of clinical and treatment factors to identify significant correlations. Additionally, the Lyman-Kutcher-Burman (LKB), Relative Seriality (RS), and Logit NTCP models were used to fit the clinical data. The fitting of the different models was assessed through the area under the receiver operating characteristic curve (AUC), Akaike information criterion (AIC), and Odds Ratio methods.
The clinical/treatment factors that were found to have a significant or close to significant correlations with acute CBOS were Age at the time of CK (P-value = 0.03), Maximum carotid dose (P-value = 0.06), and CK prescription dose (P-value = 0.08). Using D , physical DVH, and EQD -DVH as the dosimetric metrics in the NTCP models, the derived LKB model parameters were: (a) D = 45.8 Gy, m = 0.24, n = n/a; (b) D = 44.8 Gy, m = 0.28, n = 0.01; and (c) D = 115.8 Gy, m = 0.45, n = 0.01, respectively. The AUC values for the dosimetric metrics were 0.70, 0.68, and 0.61, respectively. The differences in AIC between the different models were less than 2 and ranged within ±0.9.
The maximum dose to the internal carotid less than 34 Gy appears to significantly reduce the risk for CBOS. Age at the time of CK, Maximum carotid dose, and CK prescription dose were also found to correlate with CBOS. The values of the parameters of three NTCP models were determined for this endpoint. A threshold of gEUD <34.5 Gy appears to be significantly associated with lower risks of CBOS.
估计三种常用 NTCP 模型的放射生物学参数，这些模型描述了立体定向体部放射治疗（SBRT）后颈动脉破裂综合征（CBOS）的剂量反应关系。评估这些模型的拟合优度以及与 CBOS 的相关性。
本研究纳入了 61 例 2007 年 6 月至 2011 年 3 月在土耳其安卡拉哈塞特佩大学放射肿瘤学系接受 CyberKnife（Accuray，加利福尼亚州森尼韦尔）SBRT 治疗的无法手术的局部复发性头颈部癌症患者。从所有患者的计划中导出了内颈动脉的剂量-体积直方图。回顾性收集了与颈动脉破裂综合征终点相关的随访结果。最初，对结局数据和一系列临床和治疗因素进行单变量分析（Wilcoxon 秩和或卡方检验）和多变量逻辑回归分析，以确定有意义的相关性。此外，使用 Lyman-Kutcher-Burman（LKB）、相对序列（RS）和 Logit NTCP 模型对临床数据进行拟合。通过受试者工作特征曲线下面积（AUC）、Akaike 信息准则（AIC）和优势比方法评估不同模型的拟合情况。
与急性 CBOS 有显著或接近显著相关性的临床/治疗因素包括 CK 时的年龄（P 值=0.03）、颈动脉最大剂量（P 值=0.06）和 CK 处方剂量（P 值=0.08）。使用 D、物理剂量-体积直方图和 EQD-DVH 作为 NTCP 模型中的剂量学指标，得出的 LKB 模型参数为：（a）D=45.8 Gy，m=0.24，n=无；（b）D=44.8 Gy，m=0.28，n=0.01；（c）D=115.8 Gy，m=0.45，n=0.01。剂量学指标的 AUC 值分别为 0.70、0.68 和 0.61。不同模型之间的 AIC 差异小于 2，范围在±0.9 以内。
内颈动脉的最大剂量小于 34 Gy 似乎显著降低了 CBOS 的风险。CK 时的年龄、颈动脉最大剂量和 CK 处方剂量也与 CBOS 相关。为该终点确定了三个 NTCP 模型的参数值。gEUD <34.5 Gy 的阈值似乎与较低的 CBOS 风险显著相关。
