Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA.
Int J Radiat Oncol Biol Phys. 2012 Jan 1;82(1):37-42. doi: 10.1016/j.ijrobp.2010.09.041. Epub 2010 Nov 17.
Several recent series evaluating external beam accelerated partial breast irradiation (PBI) have reported adverse cosmetic outcomes, possibly related to large volumes of normal tissue receiving near-prescription doses. We hypothesized that delivery of external beam PBI in a single fraction to the preoperative tumor volume would be feasible and result in a decreased dose to the uninvolved breast compared with institutional postoperative PBI historical controls.
A total of 17 patients with unifocal Stage T1 breast cancer were identified. Contrast-enhanced subtraction magnetic resonance images were loaded into an Eclipse treatment planning system and used to define the target volumes. A "virtual plan" was created using four photon beams in a noncoplanar beam arrangement and optimized to deliver 15 Gy to the planning target volume.
The median breast volume was 1,713 cm(3) (range: 1,014-2,140), and the median clinical target volume was 44 cm(3) (range: 26-73). In all cases, 100% of the prescription dose covered 95% of the clinical target volume. The median conformity index was 0.86 (range: 0.70-1.12). The median percentage of the ipsilateral breast volume receiving 100% and 50% of the prescribed dose was 3.8% (range: 2.2-6.9) and 13.3% (range: 7.5-20.8) compared with 18% (range: 3-42) and 53% (range: 24-65) in the institutional historical controls treated with postoperative external beam PBI (p = .002). The median maximum skin dose was 9 Gy. The median dose to 1 and 10 cm(3) of skin was 6.7 and 4.9 Gy. The doses to the heart and ipsilateral lung were negligible.
Preoperative PBI resulted in a substantial reduction in ipsilateral breast tissue dose compared with postoperative PBI. The skin dose appeared reasonable, given the small volumes. A prospective Phase I trial evaluating this technique is ongoing.
最近有几项评估体外加速部分乳腺照射（PBI）的系列研究报告了不良的美容结果，这可能与接受接近处方剂量的大量正常组织有关。我们假设，单次分割将体外 PBI 施用于术前肿瘤体积是可行的，与机构术后 PBI 历史对照相比，会使未受累乳房的剂量降低。
共确定了 17 例单发 T1 期乳腺癌患者。对增强减影磁共振成像进行加载，并将其用于定义靶区。使用非共面射束排列的四个光子束创建“虚拟计划”，并对其进行优化，以将 15 Gy 输送至计划靶区。
中位乳房体积为 1713cm³（范围：1014-2140），中位临床靶区体积为 44cm³（范围：26-73）。在所有情况下，100%的处方剂量覆盖了 95%的临床靶区。中位适形指数为 0.86（范围：0.70-1.12）。同侧乳房体积接受 100%和 50%处方剂量的中位数百分比分别为 3.8%（范围：2.2-6.9）和 13.3%（范围：7.5-20.8），而机构历史对照中接受术后外照射 PBI 治疗的患者分别为 18%（范围：3-42）和 53%（范围：24-65）（p =.002）。中位最大皮肤剂量为 9 Gy。中位 1 和 10cm³皮肤剂量分别为 6.7 和 4.9 Gy。心脏和同侧肺的剂量可忽略不计。
与术后 PBI 相比，术前 PBI 可显著降低同侧乳房组织的剂量。考虑到体积较小，皮肤剂量似乎是合理的。一项评估该技术的前瞻性 I 期试验正在进行中。
