Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistraße 15, 81377, Munich, Germany.
Institute of Radiation Protection, Helmholtz Zentrum München, Neuherberg, Germany.
Strahlenther Onkol. 2018 Mar;194(3):196-205. doi: 10.1007/s00066-017-1213-y. Epub 2017 Sep 15.
Modern breast cancer radiotherapy techniques, such as respiratory-gated radiotherapy in deep-inspiration breath-hold (DIBH) or volumetric-modulated arc radiotherapy (VMAT) have been shown to reduce the high dose exposure of the heart in left-sided breast cancer. The aim of the present study was to comparatively estimate the excess relative and absolute risks of radiation-induced secondary lung cancer and ischemic heart disease for different modern radiotherapy techniques.
Four different treatment plans were generated for ten computed tomography data sets of patients with left-sided breast cancer, using either three-dimensional conformal radiotherapy (3D-CRT) or VMAT, in free-breathing (FB) or DIBH. Dose-volume histograms were used for organ equivalent dose (OED) calculations using linear, linear-exponential, and plateau models for the lung. A linear model was applied to estimate the long-term risk of ischemic heart disease as motivated by epidemiologic data. Excess relative risk (ERR) and 10-year excess absolute risk (EAR) for radiation-induced secondary lung cancer and ischemic heart disease were estimated for different representative baseline risks.
The DIBH maneuver resulted in a significant reduction of the ERR and estimated 10-year excess absolute risk for major coronary events compared to FB in 3D-CRT plans (p = 0.04). In VMAT plans, the mean predicted risk reduction through DIBH was less pronounced and not statistically significant (p = 0.44). The risk of radiation-induced secondary lung cancer was mainly influenced by the radiotherapy technique, with no beneficial effect through DIBH. VMAT plans correlated with an increase in 10-year EAR for radiation-induced lung cancer as compared to 3D-CRT plans (DIBH p = 0.007; FB p = 0.005, respectively). However, the EARs were affected more strongly by nonradiation-associated risk factors, such as smoking, as compared to the choice of treatment technique.
The results indicate that 3D-CRT plans in DIBH pose the lowest risk for both major coronary events and secondary lung cancer.
现代乳腺癌放射治疗技术，如深吸气屏气（DIBH）中的呼吸门控放射治疗或容积调制弧形放射治疗（VMAT），已被证明可以降低左侧乳腺癌中心脏的高剂量照射。本研究旨在比较估计不同现代放射治疗技术的放射性继发性肺癌和缺血性心脏病的超额相对和绝对风险。
使用线性、线性-指数和平台模型对来自左侧乳腺癌患者的 10 个 CT 数据集的四种不同治疗计划进行了计算，这些模型用于自由呼吸（FB）或 DIBH 中的 3D-CRT 或 VMAT。使用剂量体积直方图计算器官等效剂量（OED）。线性模型用于根据流行病学数据估计缺血性心脏病的长期风险。对于不同的代表性基线风险，估计了放射性继发性肺癌和缺血性心脏病的超额相对风险（ERR）和 10 年超额绝对风险（EAR）。
与 FB 相比，DIBH 可显著降低 3D-CRT 计划中放射性继发性肺癌和主要冠状动脉事件的 ERR 和估计的 10 年超额绝对风险（p=0.04）。在 VMAT 计划中，通过 DIBH 预测的风险降低幅度较小，且无统计学意义（p=0.44）。放射性继发性肺癌的风险主要受放射治疗技术的影响，DIBH 无获益。与 3D-CRT 计划相比，VMAT 计划的 10 年 EAR 增加与放射性肺癌有关（DIBH p=0.007；FB p=0.005）。然而，EAR 受到非放射相关危险因素的影响更大，如吸烟，而不是治疗技术的选择。
结果表明，DIBH 中的 3D-CRT 计划对主要冠状动脉事件和继发性肺癌的风险最低。
