Department of Medical Physics, Mary Bird Perkins Cancer Center, Baton Rouge, LA, USA.
Phys Med Biol. 2010 Dec 7;55(23):6987-98. doi: 10.1088/0031-9155/55/23/S02. Epub 2010 Nov 12.
Theoretical calculations have shown that proton therapy can reduce the incidence of radiation-induced secondary malignant neoplasms (SMN) compared with photon therapy for patients with prostate cancer. However, the uncertainties associated with calculations of SMN risk had not been assessed. The objective of this study was to quantify the uncertainties in projected risks of secondary cancer following contemporary proton and photon radiotherapies for prostate cancer. We performed a rigorous propagation of errors and several sensitivity tests to estimate the uncertainty in the ratio of relative risk (RRR) due to the largest contributors to the uncertainty: the radiation weighting factor for neutrons, the dose-response model for radiation carcinogenesis and interpatient variations in absorbed dose. The interval of values for the radiation weighting factor for neutrons and the dose-response model were derived from the literature, while interpatient variations in absorbed dose were taken from actual patient data. The influence of each parameter on a baseline RRR value was quantified. Our analysis revealed that the calculated RRR was insensitive to the largest contributors to the uncertainty. Uncertainties in the radiation weighting factor for neutrons, the shape of the dose-risk model and interpatient variations in therapeutic and stray doses introduced a total uncertainty of 33% to the baseline RRR calculation.
理论计算表明，与光子治疗相比，前列腺癌患者接受质子治疗可以降低放射性继发性恶性肿瘤（SMN）的发生率。然而，与 SMN 风险计算相关的不确定性尚未得到评估。本研究的目的是量化当代质子和光子放射治疗前列腺癌后继发癌症风险的不确定性。我们通过严格的误差传播和几项敏感性测试来估计由于不确定性的最大贡献者（中子的辐射权重因子、辐射致癌的剂量反应模型以及患者间吸收剂量的变化）导致的相对风险比（RRR）的不确定性。中子的辐射权重因子和剂量反应模型的区间值来自文献，而吸收剂量的患者间变化则取自实际患者数据。量化了每个参数对基线 RRR 值的影响。我们的分析表明，计算出的 RRR 对不确定性的最大贡献者不敏感。中子的辐射权重因子、剂量风险模型的形状以及治疗和散射线的患者间变化的不确定性给基线 RRR 计算引入了 33%的总不确定性。
