Assessment of uncertainties in radiation-induced cancer risk predictions at clinically relevant doses
Assessment of uncertainties in radiation-induced cancer risk predictions at clinically relevant doses
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DOI：
10.1118/1.4903272
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发表时间：
2015-01-01
期刊：
影响因子：
3.8
通讯作者：
Paganetti, H.
中科院分区：
文献类型：
--
作者：
Nguyen, J.;Moteabbed, M.;Paganetti, H.
目的：理论剂量-反应模型提供了评估外束治疗后二次癌诱导风险的可能性。这些模型中使用的参数是根据流行病学研究的有限数据确定的。因此，风险估计与相当大的不确定性有关。本研究旨在通过选择脑癌患者的治疗方案，说明在原发性放疗领域预测器官特异性第二癌风险时的不确定性。方法：本研究采用一种广泛使用的风险模型。模型参数的不确定性用不同器官的二次癌症发病率的报告数据来估计。然后应用标准误差传播来评估风险模型中的不确定性。其次，计算5例小儿头颈部肿瘤患者的二次癌风险。对于每个病例，质子和光子治疗计划的设计是为了估计(a)给定治疗方式的终生归因风险（LAR）和(b)比较两种不同治疗方式的风险时的不确定性。结果：几乎所有器官的不确定性都超过了100%的风险。当应用于治疗方案时，计算的LAR值具有相同大小的不确定性。然而，对不同治疗方式的癌症风险进行比较，确实得出了具有统计学意义的结论。在本研究病例中，脑癌、脑肉瘤和骨肉瘤的质子和光子治疗的平均LAR比值分别为0.35、0.56和0.59。根据剂量学的不确定度，估计它们相应的不确定度可能低于5%。结论：癌症风险模型中剂量-反应曲线的不确定性使得目前预测单个外束治疗的风险不切实际。另一方面，两种模式之间的绝对风险之比对风险模型中的不确定性不太敏感，可以提供统计上显著的估计。(c) 2015年美国医学物理学家协会。
Purpose: Theoretical dose-response models offer the possibility to assess second cancer induction risks after external beam therapy. The parameters used in these models are determined with limited data from epidemiological studies. Risk estimations are thus associated with considerable uncertainties. This study aims at illustrating uncertainties when predicting the risk for organ-specific second cancers in the primary radiation field illustrated by choosing selected treatment plans for brain cancer patients.Methods: A widely used risk model was considered in this study. The uncertainties of the model parameters were estimated with reported data of second cancer incidences for various organs. Standard error propagation was then subsequently applied to assess the uncertainty in the risk model. Next, second cancer risks of five pediatric patients treated for cancer in the head and neck regions were calculated. For each case, treatment plans for proton and photon therapy were designed to estimate the uncertainties (a) in the lifetime attributable risk (LAR) for a given treatment modality and (b) when comparing risks of two different treatment modalities.Results: Uncertainties in excess of 100% of the risk were found for almost all organs considered. When applied to treatment plans, the calculated LAR values have uncertainties of the same magnitude. A comparison between cancer risks of different treatment modalities, however, does allow statistically significant conclusions. In the studied cases, the patient averaged LAR ratio of proton and photon treatments was 0.35, 0.56, and 0.59 for brain carcinoma, brain sarcoma, and bone sarcoma, respectively. Their corresponding uncertainties were estimated to be potentially below 5%, depending on uncertainties in dosimetry.Conclusions: The uncertainty in the dose-response curve in cancer risk models makes it currently impractical to predict the risk for an individual external beam treatment. On the other hand, the ratio of absolute risks between two modalities is less sensitive to the uncertainties in the risk model and can provide statistically significant estimates. (c) 2015 American Association of Physicists in Medicine.