Department of Radiation Oncology, University of Michigan Comprehensive Cancer Center, University of Michigan, Ann Arbor, MI 48109-5010, USA.
Int J Radiat Oncol Biol Phys. 2010 Jan 1;76(1):71-8. doi: 10.1016/j.ijrobp.2009.01.041.
To report interim cosmetic results and toxicity from a prospective study evaluating accelerated partial-breast irradiation (APBI) administered using a highly conformal external beam approach.
We enrolled breast cancer patients in an institutional review board-approved prospective study of APBI using beamlet intensity-modulated radiotherapy (IMRT) at deep-inspiration breath-hold. Patients received 38.5 Gy in 3.85 Gy fractions twice daily. Dosimetric parameters in patients who maintained acceptable cosmesis were compared with those in patients developing unacceptable cosmesis in follow-up, using t-tests.
Thirty-four patients were enrolled; 2 were excluded from analysis because of fair baseline cosmesis. With a median follow-up of 2.5 years, new unacceptable cosmesis developed in 7 patients, leading to early study closure. We compared patients with new unacceptable cosmesis with those with consistently acceptable cosmesis. Retrospective analysis demonstrated that all but one plan adhered to the dosimetric requirements of the national APBI trial. The mean proportion of a whole-breast reference volume receiving 19.25 Gy (V50) was lower in patients with acceptable cosmesis than in those with unacceptable cosmesis (34.6% vs. 46.1%; p = 0.02). The mean percentage of this reference volume receiving 38.5 Gy (V100) was also lower in patients with acceptable cosmesis (15.5% vs. 23.0%; p = 0.02).
The hypofractionated schedule and parameters commonly used for external beam APBI and prescribed by the ongoing national trial may be suboptimal, at least when highly conformal techniques such as IMRT with management of breathing motion are used. The V50 and V100 of the breast reference volume seem correlated with cosmetic outcome, and stricter limits may be appropriate in this setting.
报告一项使用高度适形外照射方法评估加速部分乳房照射（APBI）的前瞻性研究的中期美容结果和毒性。
我们在一项机构审查委员会批准的使用深吸气屏气的射束强度调制放疗（IMRT）进行 APBI 的前瞻性研究中招募了乳腺癌患者。患者接受每日两次共 38.5 Gy 的 3.85 Gy 分次照射。使用 t 检验比较在随访中保持可接受美容效果的患者和出现不可接受美容效果的患者的剂量学参数。
共纳入 34 例患者；2 例因基线美容效果尚可而被排除分析。中位随访 2.5 年后，7 例患者出现新的不可接受的美容效果，导致研究提前关闭。我们将有新的不可接受美容效果的患者与一直有可接受美容效果的患者进行比较。回顾性分析表明，除 1 例外，所有计划均符合国家 APBI 试验的剂量学要求。在可接受美容效果的患者中，整个乳房参考体积接受 19.25 Gy（V50）的平均比例低于不可接受美容效果的患者（34.6%比 46.1%；p = 0.02）。在可接受美容效果的患者中，该参考体积接受 38.5 Gy（V100）的平均百分比也较低（15.5%比 23.0%；p = 0.02）。
当使用高度适形技术（如结合呼吸运动管理的 IMRT）时，外照射 APBI 常用的分次方案和参数（由正在进行的国家试验规定）可能不够理想。乳房参考体积的 V50 和 V100 似乎与美容结果相关，在这种情况下可能需要更严格的限制。
