Department of Radiation Oncology, Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah.
Department of Radiation Oncology, Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah.
Int J Radiat Oncol Biol Phys. 2023 Sep 1;117(1):274-280. doi: 10.1016/j.ijrobp.2023.03.071. Epub 2023 Apr 5.
The objective of this work was to evaluate dosimetric characteristics to organs at risk (OARs) from short-course adjuvant vaginal cuff brachytherapy (VCB) in early endometrial cancer compared with standard of care (SOC) in a multi-institutional prospective randomized trial.
SAVE (Short Course Adjuvant Vaginal Brachytherapy in Early Endometrial Cancer Compared to Standard of Care) is a prospective, phase 3, multisite randomized trial in which 108 patients requiring VCB were randomized to an experimental short-course arm (11 Gy × 2 fractions [fx] to surface) and SOC arm. Those randomized to the SOC arm were subdivided into treatment groups based on treating physician discretion as follows: 7 Gy × 3 fx to 5 mm, 5 to 5.5 Gy × 4 fx to 5 mm, and 6 Gy × 5 fx to surface. To evaluate doses to OARs of each SAVE cohort, the rectum, bladder, sigmoid, small bowel, and urethra were contoured on planning computed tomography, and doses to OARs were compared by treatment arm. Absolute doses for each OAR and from each fractionation scheme were converted to 2 Gy equivalent dose (EQD2). Each SOC arm was compared with the experimental arm separately using 1-way analysis of variance, followed by pairwise comparisons using Tukey's honestly significant difference test.
The experimental arm had significantly lower doses for rectum, bladder, sigmoid, and urethra compared with the 7 Gy × 3 and 5 to 5.5 Gy × 4 fractionation schemes; however, the experimental arm did not differ from the 6 Gy × 5 fractionation scheme. For small bowel doses, none of the SOC fractionation schemes were statistically different than the experimental. The highest EQD2 doses to the examined OARs were observed to come from the most common dose fractionation scheme of 7 Gy × 3 fx. With a short median follow-up of 1 year, there have been no isolated vaginal recurrences.
Experimental short-course VCB of 11 Gy × 2 fx to the surface provides a comparable biologically effective dose to SOC courses. Experimental short-course VCB was found to reduce or be comparable to D2cc and D0.1cc EQD2 doses to rectum, bladder, sigmoid, small bowel, and urethra critical structures. This may translate into a comparable or lower rate of acute and late adverse effects.
本研究旨在通过多机构前瞻性随机试验，评估早期子宫内膜癌辅助阴道袖口近距离放疗（VCB）短疗程与标准治疗（SOC）相比，对危及器官（OARs）的剂量学特征。
SAVE（早期子宫内膜癌中与标准治疗相比的短程辅助阴道近距离放疗）是一项前瞻性、III 期、多中心随机试验，其中 108 例需要 VCB 的患者被随机分配到实验组（11 Gy×2 次分割[fx]至表面）和 SOC 组。SOC 组根据治疗医生的判断进一步分为治疗组，具体如下：7 Gy×3 fx 至 5 mm、5 至 5.5 Gy×4 fx 至 5 mm 和 6 Gy×5 fx 至表面。为了评估每个 SAVE 队列的 OAR 剂量，直肠、膀胱、乙状结肠、小肠和尿道在计划 CT 上进行了轮廓勾画，并按治疗臂比较 OAR 剂量。每个 OAR 的绝对剂量和每个分割方案的剂量均转换为 2 Gy 等效剂量（EQD2）。每个 SOC 臂分别与实验组进行单因素方差分析比较，然后采用 Tukey 的诚实显著差异检验进行两两比较。
与 7 Gy×3 和 5 至 5.5 Gy×4 分割方案相比，实验组的直肠、膀胱、乙状结肠和尿道剂量显著降低；然而，实验组与 6 Gy×5 分割方案无差异。对于小肠剂量，SOC 分割方案均与实验组无统计学差异。观察到检查 OAR 中最高的 EQD2 剂量来自最常见的 7 Gy×3 fx 剂量分割方案。中位随访时间仅为 1 年，尚未出现孤立的阴道复发。
11 Gy×2 fx 至表面的实验性短疗程 VCB 提供了与 SOC 疗程相当的生物有效剂量。实验性短疗程 VCB 降低或与直肠、膀胱、乙状结肠、小肠和尿道关键结构的 D2cc 和 D0.1cc EQD2 剂量相当。这可能转化为相当或更低的急性和晚期不良反应发生率。
