Liu Yilan, Veale Christopher, Hablitz Diana, Krontiras Helen, Dalton Allison, Meyers Korie, Dobelbower Michael, Lancaster Rachael, Bredel Markus, Parker Catherine, Keene Kimberly, Thomas Evan, Boggs Drexell
Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL, United States.
Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, United States.
Front Oncol. 2022 Jul 8;12:901312. doi: 10.3389/fonc.2022.901312. eCollection 2022.
For appropriately selected patients with early-stage breast cancer (ESBC), accelerated partial breast irradiation (APBI) yields equivalent rates of ipsilateral breast tumor recurrence with mixed results in patient-rated cosmesis compared with whole-breast radiotherapy depending on the technique utilized. When utilizing external beam radiotherapy for APBI, techniques to reduce target margins and overall treatment volume are potentially important to decrease rates of long-term adverse cosmesis. Stereotactic body radiotherapy (SBRT) is a promising technique to deliver APBI because of its increased accuracy and sparing of uninvolved breast tissue. We report the initial results of a prospective clinical trial investigating feasibility, safety, and cosmetic outcomes of a daily five-fraction SBRT regimen for APBI.
Twenty-three patients with ESBC after lumpectomy who met APBI suitability were enrolled. During lumpectomy, a bioabsorbable three-dimensional fixed array tissue marker (BioZorb™, Hologic, Marlborough, MA) was placed for enhanced visualization of the cavity boundaries. Clinical target volume (CTV) was defined as the delineable cavity plus a 1-cm isotropic expansion followed by a 3-mm isotropic planning target volume (PTV) expansion. Patients received 30 Gy delivered in five planned consecutive daily fractions in either prone or supine positioning depending on individual anatomy. Two patients completed the five-fraction treatments in 9-day interval and 11-day interval due to external circumstances. A maximum PTV of 124cc was allowed to minimize incidence of fat necrosis. Plans utilized 10-MV flattening filter-free beams delivered on a Varian Edge linear accelerator. Local control, toxicity, and nurse/patient-scored cosmesis at pre-treatment baseline, 1 month post-treatment, and at subsequent 6-month intervals were recorded.
Twenty-three patients were accrued at the time of submission with median follow-up of 6 months. No patients experienced grade ≥3 acute toxicity. Of the 10 events reported probably related to SBRT, nine were grade 1 (n = 9/10, 90%). There was no evidence of difference, deterioration, or change in patient or nurse-scored cosmesis from baseline to 1 and 6 months post-treatment. One patient developed nodal failure shortly after APBI.
Although longer follow-up is needed to assess long-term toxicity and local control, this study demonstrated a five-fraction SBRT regimen delivered over consecutive days is a safe, efficient, well-tolerated, and cosmetically favorable means of delivering APBI in suitable women.
https://www.clinicaltrials.gov/ct2/show/NCT03643861, NCT03643861.
对于经过适当选择的早期乳腺癌（ESBC）患者，与全乳放疗相比，加速部分乳腺照射（APBI）产生的同侧乳腺肿瘤复发率相当，但根据所采用的技术不同，患者自评的美容效果不一。在使用外照射放疗进行APBI时，减少靶区边界和总体治疗体积的技术对于降低长期不良美容效果的发生率可能很重要。立体定向体部放疗（SBRT）是一种有前景的APBI技术，因为它具有更高的准确性且能减少对未受累乳腺组织的照射。我们报告了一项前瞻性临床试验的初步结果，该试验旨在研究每日5次分割的SBRT方案用于APBI的可行性、安全性和美容效果。
纳入23例保乳术后符合APBI适应证的ESBC患者。在保乳手术期间，放置一个可生物吸收的三维固定阵列组织标记物（BioZorb™，Hologic，马尔伯勒，马萨诸塞州）以增强对腔隙边界的可视化。临床靶区体积（CTV）定义为可勾勒出的腔隙加上各向同性的1 cm扩展，随后计划靶区体积（PTV）进行各向同性的3 mm扩展。患者根据个体解剖结构采用俯卧位或仰卧位，连续5天计划给予30 Gy照射，分5次进行。由于外部情况，2例患者分别在9天和11天的间隔内完成了5次分割治疗。允许最大PTV为124 cc以尽量减少脂肪坏死的发生率。计划使用Varian Edge直线加速器上的10 MV无 flattening filter的射束。记录治疗前基线、治疗后1个月及随后每6个月的局部控制、毒性以及护士/患者评分的美容效果。
提交报告时共纳入23例患者，中位随访时间为6个月。没有患者发生≥3级急性毒性反应。在报告的10例可能与SBRT相关的事件中，9例为1级（n = 9/10，90%）。从基线到治疗后1个月和6个月，没有证据表明患者或护士评分的美容效果有差异、恶化或改变。1例患者在APBI后不久发生区域淋巴结转移。
尽管需要更长时间的随访来评估长期毒性和局部控制情况，但本研究表明，连续几天给予5次分割的SBRT方案是一种安全、有效、耐受性良好且美容效果良好的方法，适用于合适的女性进行APBI治疗。
https://www.clinicaltrials.gov/ct2/show/NCT03643861，NCT03643861。
