Department of Therapeutic Radiology, Yale School of Medicine, New Haven, Connecticut; Department of Radiation Oncology, Assistance publique-Hôpitaux de Paris, University of Paris-Est Créteil and Henri Mondor Breast Center, Créteil Cedex, France.
Department of Therapeutic Radiology, Yale School of Medicine, New Haven, Connecticut.
Pract Radiat Oncol. 2020 Jan-Feb;10(1):21-28. doi: 10.1016/j.prro.2019.07.014. Epub 2019 Aug 5.
The purpose of the study was to evaluate the incidental dose delivered to the internal mammary nodes (IMNs) in patients treated with tangential 3-dimensional conformal radiation therapy and to identify potential parameters that may affect the IMN mean dose.
The study cohort consisted of 362 consecutively treated patients with breast cancer in our center between January 2015 and July 2017 who had received adjuvant whole-breast radiation therapy or postmastectomy radiation with or without a supraclavicular ± axillary field and without intentional inclusion of the IMN chain. The clinical target volume (CTV) for the IMNs was contoured per the Radiation Therapy Oncology Group 3509/3510 protocol and was then divided into 3 subregions: upper, mid, and lower thirds. The planning target volume for the IMNs was generated by adding 5 mm to the CTV. The primary endpoint was to assess the V40 (volume receiving 40 Gy) to the IMN planning target volume and its potential influencing parameters using a linear regression model.
The mean (±standard deviation) dose to the CTV IMN chain was 36% ± 28.7%. The Kruskal-Wallis test demonstrated significant differences in the median dose delivered to each level: upper third (7.2%), mid third (21.5%), and lower third (41.7%) (P < .001). The mean V40 IMN planning target volume was 14.2% (standard deviation, 18.7%). Presternal fat thickness (regression coefficient [RC] = -16.4; P < .001), postmastectomy radiation (RC = 24; P < .001), reconstruction after mastectomy (RC = -22.4; P < .001), and the addition of a supraclavicular field (RC = 8.8; P = .03) were all significantly associated with IMN mean dose.
For patients receiving standard breast/chest wall tangential radiation fields, the IMN chain is not incidentally covered with therapeutic doses in the vast majority of cases. Therefore, if regional nodal radiation is intended to include the IMNs, contouring and careful plan review are necessary to ensure adequate therapeutic coverage.
本研究旨在评估接受切线三维适形放疗的患者中内乳淋巴结（IMN）的偶然剂量，并确定可能影响 IMN 平均剂量的潜在参数。
本研究队列包括 2015 年 1 月至 2017 年 7 月期间在我院接受辅助全乳放疗或乳房切除术放疗联合或不联合锁骨上±腋窝野且无有意包含内乳链的 362 例连续治疗的乳腺癌患者。根据放射治疗肿瘤学组 3509/3510 方案对 IMN 的临床靶区（CTV）进行轮廓勾画，并将其分为上、中、下三分之一区。内乳淋巴结的计划靶区通过向 CTV 外扩 5mm 生成。主要终点是使用线性回归模型评估 IMN 计划靶区的 V40（接受 40Gy 的体积）及其潜在影响参数。
CTV 内乳链的平均（±标准差）剂量为 36%±28.7%。Kruskal-Wallis 检验显示，各水平间的中位剂量存在显著差异：上三分之一区（7.2%）、中三分之一区（21.5%）和下三分之一区（41.7%）（P<0.001）。IMN 计划靶区的平均 V40 为 14.2%（标准差，18.7%）。胸骨前脂肪厚度（回归系数[RC]=-16.4；P<0.001）、乳房切除术放疗（RC=24；P<0.001）、乳房切除术重建（RC=-22.4；P<0.001）和锁骨上野的添加（RC=8.8；P=0.03）均与 IMN 平均剂量显著相关。
对于接受标准乳房/胸壁切线放疗的患者，IMN 链在绝大多数情况下不会偶然受到治疗剂量的照射。因此，如果区域淋巴结放疗有意包括内乳淋巴结，需要进行轮廓勾画和仔细的计划审查，以确保足够的治疗覆盖。
