Department of Radiation Oncology, University of Pittsburgh Cancer Institute, Pittsburgh, PA, USA.
Radiat Oncol. 2012 Sep 24;7:163. doi: 10.1186/1748-717X-7-163.
The purpose of this study was to compare the change in depth of target volume and dosimetric parameters between the supine and lateral decubitus positions for breast boost treatment with electron beam therapy.
We analyzed 45 patients who were treated, between 2009-2010, with whole breast radiation (WBRT) followed by a tumor bed boost in the lateral decubitius position. Tumor bed volume, distance from skin to the maximal depth of the tumor bed, D90 (dose covering 90% of the tumor bed volume), maximal dose, electron energy and doses to heart and lungs were compared. Additional variables of body mass index (BMI) and tumor bed location were also analyzed to see if there was a benefit limited to any subgroup.
Median BMI for the 45 patients treated was 30.6 (20.6-42.4). When comparing the supine scan to the lateral decubitus scan, there was no significant difference in the tumor bed volume (p = 0.116). There was a significant difference between depth to the tumor bed in the supine scan and lateral decubitus scan (p < 0.001). The mean maximum doses and D90 between the two scans were 110.7 (100.0-133.0)% vs 106.1 (95.1-116.9)% (p < 0.05) and 93.9 (81.3-01.0-101.0)% vs. 98.2 (89.1-108.0)% (p = 0.004) respectively. There was no difference in dose delivered to the lungs or heart between the two scans (p = 0.848 and p = 0.992 respectively). On subset analysis, there was a difference in depth to tumor that was seen across all BMI classes, including normal (p ≤ 0.001, overweight (p ≤ 0.001) and obese (p ≤ 0.001). The majority of patients had a tumor in the upper outer quadrant (77.8%) and on subset analysis, there was a significant difference in tumor bed volume (p < 0.01), depth to tumor (p < 0.01), tumor bed coverage [D90] (p < 0.05), maximum dose (p < 0.05) and energy (p < 0.001) for this location.
Delivering a tumor bed boost in the lateral decubitus position reduces the distance to the tumor bed allowing for a lower energy treatment to be used to treat breast cancer. It improves coverage and decreases maximal dose to the target volume, all of which would help reduce skin morbidities and should be considered for patients with upper outer quadrant disease, irrespective of BMI status.
本研究旨在比较电子束治疗乳房提升时仰卧位和侧卧位靶区深度和剂量学参数的变化。
我们分析了 2009-2010 年间接受全乳放疗（WBRT）后在侧卧位进行肿瘤床加量治疗的 45 例患者。比较肿瘤床体积、距肿瘤床最大深度的皮肤距离、覆盖 90%肿瘤床体积的剂量（D90）、最大剂量、电子能量以及心脏和肺部剂量。还分析了体重指数（BMI）和肿瘤床位置等其他变量，以观察是否仅限于任何亚组有获益。
45 例接受治疗患者的中位 BMI 为 30.6（20.6-42.4）。与仰卧位扫描相比，侧卧位扫描时肿瘤床体积无显著差异（p=0.116）。仰卧位和侧卧位扫描时肿瘤床深度有显著差异（p<0.001）。两种扫描方式的最大剂量和 D90 平均值分别为 110.7（100.0-133.0）%比 106.1（95.1-116.9）%（p<0.05）和 93.9（81.3-93.9）%比 98.2（89.1-108.0）%（p=0.004）。两种扫描方式肺和心脏的剂量无差异（p=0.848 和 p=0.992）。亚组分析显示，所有 BMI 类别（包括正常体重组、超重组和肥胖组）均存在肿瘤深度差异（p≤0.001）。大多数患者肿瘤位于外上象限（77.8%），亚组分析显示肿瘤床体积（p<0.01）、肿瘤床深度（p<0.01）、肿瘤床覆盖率[D90]（p<0.05）、最大剂量（p<0.05）和能量（p<0.001）有显著差异。
在侧卧位进行肿瘤床加量治疗可减少与肿瘤的距离，从而可以使用较低能量的治疗方法治疗乳腺癌。它可以提高靶区覆盖率，降低靶区最大剂量，这都有助于降低皮肤并发症，对于外上象限疾病的患者应考虑采用，而不论 BMI 状态如何。
