Department of Radiation Oncology, University of Arizona, Tucson, AZ.
Department of Epidemiology and Biostatistics, University of Arizona Cancer Center, Tucson, AZ.
Clin Breast Cancer. 2021 Aug;21(4):e295-e301. doi: 10.1016/j.clbc.2020.11.004. Epub 2020 Nov 13.
With advances in treatment, outcomes for early-stage breast cancer are improving. We investigated the combination of prone position and deep inspiration breath hold to decrease cardiac doses for left-sided breast radiotherapy.
Fifteen patients with left-sided breast cancer were enrolled on a single-institution prospective study. Each patient underwent 2 prone positioned computed tomography simulation scans utilizing free breathing and breath-hold. Separate treatment plans for each computed tomography simulation scan were created using tangential fields, and heart and left lung doses were compared between free breathing and breath-hold plans. The technique with the lower mean dose for the heart was used for treatment. All patients were treated with a hypofractionated regimen of 40 to 42 Gy in 15 to 16 fractions, followed by a lumpectomy cavity boost of 10 Gy in 5 fractions when indicated. Wilcoxon paired signed rank tests and paired t tests were performed for statistical analysis of dosimetric endpoints.
The median age of our patients was 58 years (range, 40-72 years). One patient was not able to tolerate prone positioning at simulation, leaving 14 patients with evaluable paired scans. The average mean heart dose with free breathing and with breath-hold was 0.93 Gy and 0.72 Gy, respectively (P = .0063). The average max heart dose with free breathing and with breath-hold was 15.70 Gy and 7.19 Gy, respectively (P = .001). The average mean left lung dose with free breathing and with breath-hold was 0.65 Gy and 0.88 Gy, respectively (P = .011).
Our results indicate that breath-hold using the real-time position management system may provide additional cardiac dose reduction in patients receiving prone left-breast radiotherapy treated with tangential fields.
随着治疗的进步，早期乳腺癌的治疗效果正在改善。我们研究了俯卧位和深吸气屏气相结合的方法，以降低左侧乳腺癌放疗中的心脏剂量。
在单机构前瞻性研究中纳入了 15 例左侧乳腺癌患者。每位患者均进行了 2 次俯卧位 CT 模拟扫描，分别采用自由呼吸和屏气。为每个 CT 模拟扫描创建了单独的治疗计划，使用切线野，比较了自由呼吸和屏气计划中心脏和左肺的剂量。采用心脏平均剂量较低的技术进行治疗。所有患者均接受了 40 至 42Gy 的分割剂量治疗（15-16 次分割），如果需要，在接受治疗后进行 10Gy 的瘤床局部推量照射（5 次分割）。采用 Wilcoxon 配对符号秩检验和配对 t 检验对剂量学终点进行统计学分析。
患者的中位年龄为 58 岁（范围为 40-72 岁）。1 例患者在模拟时无法耐受俯卧位，因此有 14 例患者可进行配对扫描评估。自由呼吸和屏气时的平均心脏剂量分别为 0.93Gy 和 0.72Gy（P=0.0063）。自由呼吸和屏气时的最大心脏剂量分别为 15.70Gy 和 7.19Gy（P=0.001）。自由呼吸和屏气时的平均左肺剂量分别为 0.65Gy 和 0.88Gy（P=0.011）。
我们的结果表明，使用实时位置管理系统进行屏气可能会为接受切线野照射的俯卧位左侧乳腺癌放疗患者提供额外的心脏剂量降低。
