Department of Radiation Oncology, Virginia Commonwealth University, Medical College of Virginia Campus, 401 College St., Box 980058, Richmond, VA 23298, USA.
Int J Radiat Oncol Biol Phys. 2011 Nov 1;81(3):e173-7. doi: 10.1016/j.ijrobp.2010.12.023. Epub 2011 Feb 9.
Multiple investigations have used the skin distance as a surrogate for the skin dose and have shown that distances <6 mm have been associated with late toxicity after MammoSite brachytherapy. No publications have yet described the relationship between the actual maximal skin dose and the outcome. The present study analyzed the maximal skin dose delivered and the occurrence of late toxicity in a large cohort of patients with prolonged follow-up.
A total of 96 patients treated with breast brachytherapy between 2000 and 2007 for whom complete planning and follow-up data were available were included in the present analysis. The median follow-up was 48 months (range, 24-111). Of the 96 patients, 40 were treated with multicatheter interstitial brachytherapy and 56 with MammoSite. A multivariate statistical analysis was performed to determine the relationship between several dosimetric parameters and patient outcome.
The treatment was well tolerated, with 98% of patients experiencing good to excellent cosmesis. Significant late toxicity was uncommon. The maximal dose delivered to the skin was significantly associated with the incidence of any degree of telangiectasia (p = .009) and moderate to severe fibrosis (p = .010). The incidence of late toxicity was significantly increased when the dose to the skin was >4.05 Gy/fraction.
The initial skin dose recommendations have been based on safe use and the avoidance of significant toxicity. The results from the present study have suggested that patients might further benefit if more rigorous constraints were applied and if the skin dose were limited to 120% of the prescription dose.
多项研究已将皮肤距离用作皮肤剂量的替代物，并表明距离<6mm 与 MammoSite 近距离放射治疗后的晚期毒性有关。目前还没有文献描述实际最大皮肤剂量与结果之间的关系。本研究分析了大量接受延长随访的患者的最大皮肤剂量分布与晚期毒性的关系。
本研究共纳入 96 例 2000 年至 2007 年接受乳腺近距离放射治疗的患者，这些患者具有完整的计划和随访数据。中位随访时间为 48 个月（范围：24-111）。96 例患者中，40 例接受多导管间质内近距离放射治疗，56 例接受 MammoSite 治疗。采用多变量统计分析来确定几个剂量学参数与患者结局之间的关系。
治疗耐受良好，98%的患者美容效果良好至优秀。晚期毒性显著罕见。皮肤接受的最大剂量与任何程度的毛细血管扩张（p=0.009）和中重度纤维化（p=0.010）的发生率显著相关。当皮肤剂量>4.05Gy/分次时，晚期毒性的发生率显著增加。
最初的皮肤剂量推荐是基于安全使用和避免显著毒性。本研究的结果表明，如果应用更严格的限制并且将皮肤剂量限制在处方剂量的 120%，患者可能会进一步受益。
