Chen Hongtao, Piao Ying, Yang Dong, Kuang Peipei, Li Zihuang, Liao Guixiang, Zhong Heli
Department of Radiation Oncology, Shenzhen People's Hospital, the Second Clinical Medical College, Jinan University, Shenzhen, China.
Front Oncol. 2022 Oct 3;12:989220. doi: 10.3389/fonc.2022.989220. eCollection 2022.
A subsequent cardiac toxicity is deemed to be dose-dependent for left-sided breast cancer irradiation. This study aims to demonstrate the effect of respiratory capacity for dose sparing when the deep inspiration breath hold with Active Breathing Coordinator technique (ABC-DIBH) is used in left-sided breast cancer irradiation.
74 left-sided breast cancer patients, who received whole breast or post-mastectomy chest wall radiotherapy with ABC-DIBH between 2020 and 2021 in our center, were retrospectively reviewed in this study. CT scans of free breath (FB) and ABC-DIBH were done for each patient, and two treatment plans with a prescription dose of 5000 cGy/25 Fr were designed separately. The dose to heart, left anterior descending artery (LAD) and lungs was compared between FB and ABC-DIBH. The correlation between individual parameters (dose to organs at risk (OARs) and minimum heart distance (MHD)) was analyzed, and the effect of respiratory capacity for dose sparing was assessed.
The plans with ABC-DIBH achieved lower Dmean for heart (34.80%, P < 0.01) and LAD (29.33%, P < 0.01) than those with FB. Regression analysis revealed that both Dmean and D2 of heart were negatively correlated with MHD in the plans with FB and ABC-DIBH, which decreased with the increase in MHD by 37.8 cGy and 309.9 cGy per 1mm, respectively. Besides, a lower Dmean of heart was related to a larger volume of ipsilateral lung in plans with FB. With the increase in volume of ipsilateral lung, the linear correlation was getting weaker and weaker until the volume of ipsilateral lung reached 1700 cc. Meanwhile, a negative linear correlation between Dmean of LAD and MHD in plans with FB and ABC-DIBH was observed, whose slope was 162.5 and 135.9 cGy/mm, respectively. Furthermore, when the respiratory capacity of ABC-DIBH reached 1L, and the relative ratio (ABC-DIBH/FB) reached 3.6, patients could obtain the benefit of dose sparing. The larger difference in respiratory capacity had no significant effect in the larger difference of MHD, Dmean of heart and Dmean of LAD between FB and ABC-DIBH.
This study demonstrates the sufficiently good effect of ABC-DIBH when utilizing for cardiac sparing. It also reveals the correlations among individual parameters and the effect of respiratory capacity for dose sparing. This helps take optimal advantage of the ABC-DIBH technique and predict clinical benefits.
左侧乳腺癌放疗后发生的心脏毒性被认为与剂量相关。本研究旨在探讨在左侧乳腺癌放疗中采用主动呼吸控制技术的深吸气屏气（ABC-DIBH）时，呼吸能力对剂量 sparing 的影响。
回顾性分析 2020 年至 2021 年在本中心接受 ABC-DIBH 全乳或乳房切除术后胸壁放疗的 74 例左侧乳腺癌患者。对每位患者进行自由呼吸（FB）和 ABC-DIBH 的 CT 扫描，并分别设计两个处方剂量为 5000 cGy/25 次分割的治疗计划。比较 FB 和 ABC-DIBH 时心脏、左前降支（LAD）和肺的剂量。分析个体参数（危及器官（OARs）剂量和最小心脏距离（MHD））之间的相关性，并评估呼吸能力对剂量 sparing 的影响。
ABC-DIBH 计划的心脏平均剂量（Dmean）（降低 34.80%，P < 0.01）和 LAD 的 Dmean（降低 29.33%，P < 0.01）低于 FB 计划。回归分析显示，在 FB 和 ABC-DIBH 计划中，心脏的 Dmean 和 D2 均与 MHD呈负相关，MHD 每增加 1mm，心脏 Dmean 分别降低 37.8 cGy 和 309.9 cGy。此外，在 FB 计划中，心脏较低的 Dmean 与同侧肺体积较大有关。随着同侧肺体积增加，线性相关性逐渐减弱，直至同侧肺体积达到 1700 cc。同时，在 FB 和 ABC-DIBH 计划中观察到 LAD 的 Dmean 与 MHD 呈负线性相关，斜率分别为 162.5 和 135.9 cGy/mm。此外，当 ABC-DIBH 的呼吸能力达到 1L，相对比值（ABC-DIBH/FB）达到 3.6 时，患者可获得剂量 sparing 的益处。呼吸能力差异较大对 FB 和 ABC-DIBH 之间 MHD、心脏 Dmean 和 LAD 的 Dmean 差异较大无显著影响。
本研究表明 ABC-DIBH 在心脏 sparing 方面具有良好效果。还揭示了个体参数之间的相关性以及呼吸能力对剂量 sparing 的影响。这有助于充分利用 ABC-DIBH 技术并预测临床获益。
