Department of Radiation Oncology, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea.
Department of Radiation Oncology, Korea University Anam Hospital, Korea University College of Medicine, Seoul 02841, Korea.
Medicina (Kaunas). 2022 Jun 29;58(7):873. doi: 10.3390/medicina58070873.
Background and Objectives: The boost dose to the tumor bed after whole breast irradiation (WBI) can be divided into sequential boost (SEQ) and simultaneous integrated boost (SIB). SIB using modern radiation therapy (RT) techniques, such as volumetric modulated arc therapy, allow the delivery of a highly conformal dose to the target volume and has a salient ability to spare at-risk organs. This study aimed to compare the radiation dose delivered to the heart and lungs according to boost technique and tumor bed location. Materials and Methods: RT planning data of 20 patients with early-stage left-sided breast cancer were used in this study. All patients were treated with volumetric modulated arc therapy after breast-conserving surgery with a sentinel lymph node biopsy. For each patient, two different plans, whole breast irradiation with simultaneous integrated boost (WBI-SIB) and sequential boost after WBI (WBI-SEQ), were generated. To compare the dose received by each organ at risk (OAR), dose-volume histogram data were analyzed. The mean dose (Dmean) and volume of each organ that received x Gy (Vx) were calculated and compared. Results: For the heart, the V10 was lower for the WBI-SIB plan than for the WBI-SEQ plan (5.223 ± 1.947% vs. 6.409 ± 2.545%, p = 0.008). For the left lung, the V5 was lower in the WBI-SIB plan than for the WBI-SEQ plan (27.385 ± 3.871% vs. 32.092 ± 3.545%, p < 0.001). The Dmean for the heart and left lung was lower for the WBI-SIB plan than for the WBI-SEQ plan (heart: 339.745 ± 46.889 cGy vs. 413.030 ± 52.456 cGy, p < 0.001; left lung: 550.445 ± 65.094 cGy vs. 602.270 ± 55.775 cGy, p < 0.001). Conclusions: The WBI-SIB plan delivered lower radiation doses to the heart and left lung than the WBI-SEQ plan in terms of Dmean and low-dose volume in hypofractionated RT of early-stage left-sided breast cancer patients. Furthermore, a large radiation dose per day may be advantageous, considering the radiobiologic aspects of breast cancer. Long-term follow-up data are needed to determine whether the dosimetric advantages of the WBI-SIB plan can lead to clinically improved patient outcomes and reduced late side effects.
全乳照射（WBI）后肿瘤床的推量可分为序贯推量（SEQ）和同时整合推量（SIB）。SIB 使用现代放射治疗（RT）技术，如容积调强弧形治疗，能够将高适形剂量递送至靶区，并具有显著保护高危器官的能力。本研究旨在比较根据推量技术和肿瘤床位置所给予的心脏和肺脏的放射剂量。
本研究使用了 20 例早期左侧乳腺癌患者的 RT 计划数据。所有患者均接受保乳手术后行前哨淋巴结活检，并接受容积调强弧形治疗。对于每位患者，均生成两种不同的计划，即全乳照射同步整合推量（WBI-SIB）和 WBI 后序贯推量（WBI-SEQ）。为了比较每个危险器官（OAR）所接受的剂量，分析了剂量-体积直方图数据。计算并比较了每个器官所接受 x Gy 的平均剂量（Dmean）和体积（Vx）。
对于心脏，WBI-SIB 计划的 V10 低于 WBI-SEQ 计划（5.223 ± 1.947% vs. 6.409 ± 2.545%，p = 0.008）。对于左肺，WBI-SIB 计划的 V5 低于 WBI-SEQ 计划（27.385 ± 3.871% vs. 32.092 ± 3.545%，p < 0.001）。WBI-SIB 计划的心脏和左肺 Dmean 低于 WBI-SEQ 计划（心脏：339.745 ± 46.889 cGy vs. 413.030 ± 52.456 cGy，p < 0.001；左肺：550.445 ± 65.094 cGy vs. 602.270 ± 55.775 cGy，p < 0.001）。
在早期左侧乳腺癌患者的部分乳腺照射（WBI）中，与 WBI-SEQ 计划相比，WBI-SIB 计划的 Dmean 和低剂量体积均能降低心脏和左肺的放射剂量。此外，考虑到乳腺癌的放射生物学方面，每日大剂量放疗可能是有利的。需要长期随访数据来确定 WBI-SIB 计划的剂量学优势是否能带来临床获益并降低晚期副作用。
