Hamstra Daniel A, Mariados Neil, Sylvester John, Shah Dhiren, Karsh Lawrence, Hudes Richard, Beyer David, Kurtzman Steven, Bogart Jeffrey, Hsi R Alex, Kos Michael, Ellis Rodney, Logsdon Mark, Zimberg Shawn, Forsythe Kevin, Zhang Hong, Soffen Edward, Francke Patrick, Mantz Constantine, Rossi Peter, DeWeese Theodore, Daignault-Newton Stephanie, Fischer-Valuck Benjamin W, Chundury Anupama, Gay Hiram, Bosch Walter, Michalski Jeff
Texas Oncology, Texas Center for Proton Therapy, Irving, Texas.
Associated Medical Professionals of NY, PLLC, Syracuse, New York.
Int J Radiat Oncol Biol Phys. 2017 Apr 1;97(5):976-985. doi: 10.1016/j.ijrobp.2016.12.024. Epub 2016 Dec 23.
SpaceOAR, a Food and Drug Administration-approved hydrogel intended to create a rectal-prostate space, was evaluated in a single-blind phase III trial of image guided intensity modulated radiation therapy. A total of 222 men were randomized 2:1 to the spacer or control group and received 79.2 Gy in 1.8-Gy fractions to the prostate with or without the seminal vesicles. The present study reports the final results with a median follow-up period of 3 years.
Cumulative (Common Terminology Criteria for Adverse Events, version 4.0) toxicity was evaluated using the log-rank test. Quality of life (QOL) was examined using the Expanded Prostate Cancer Index Composite (EPIC), and the mean changes from baseline in the EPIC domains were tested using repeated measures models. The proportions of men with minimally important differences (MIDs) in each domain were tested using repeated measures logistic models with prespecified thresholds.
The 3-year incidence of grade ≥1 (9.2% vs 2.0%; P=.028) and grade ≥2 (5.7% vs 0%; P=.012) rectal toxicity favored the spacer arm. Grade ≥1 urinary incontinence was also lower in the spacer arm (15% vs 4%; P=.046), with no difference in grade ≥2 urinary toxicity (7% vs 7%; P=0.7). From 6 months onward, bowel QOL consistently favored the spacer group (P=.002), with the difference at 3 years (5.8 points; P<.05) meeting the threshold for a MID. The control group had a 3.9-point greater decline in urinary QOL compared with the spacer group at 3 years (P<.05), but the difference did not meet the MID threshold. At 3 years, more men in the control group than in the spacer group had experienced a MID decline in bowel QOL (41% vs 14%; P=.002) and urinary QOL (30% vs 17%; P=.04). Furthermore, the control group were also more likely to have experienced large declines (twice the MID) in bowel QOL (21% vs 5%; P=.02) and urinary QOL (23% vs 8%; P=.02).
The benefit of a hydrogel spacer in reducing the rectal dose, toxicity, and QOL declines after image guided intensity modulated radiation therapy for prostate cancer was maintained or increased with a longer follow-up period, providing stronger evidence for the benefit of hydrogel spacer use in prostate radiation therapy.
SpaceOAR是一种经美国食品药品监督管理局批准的水凝胶，旨在创建直肠-前列腺间隙，在一项图像引导调强放射治疗的单盲III期试验中对其进行了评估。共有222名男性按2:1随机分为间隔物组或对照组，接受79.2 Gy，以1.8 Gy的分次剂量照射前列腺，照射时伴或不伴精囊。本研究报告了中位随访期为3年的最终结果。
使用对数秩检验评估累积（不良事件通用术语标准，第4.0版）毒性。使用扩展前列腺癌指数综合量表（EPIC）检查生活质量（QOL），并使用重复测量模型测试EPIC各领域相对于基线的平均变化。使用具有预先设定阈值的重复测量逻辑模型测试每个领域中具有最小重要差异（MID）的男性比例。
≥1级（9.2%对2.0%；P = 0.028）和≥2级（5.7%对0%；P = 0.012）直肠毒性的3年发生率有利于间隔物组。间隔物组中≥1级尿失禁也较低（15%对4%；P = 0.046），≥2级泌尿毒性无差异（7%对7%；P = 0.7）。从6个月起，肠道QOL一直有利于间隔物组（P = 0.002），3年时的差异（5.8分；P < 0.05）达到MID阈值。与间隔物组相比，对照组在3年时尿QOL下降多3.9分（P < 0.05），但差异未达到MID阈值。在3年时，对照组中经历肠道QOL和尿QOL出现MID下降的男性比间隔物组更多（41%对14%；P = 0.002）和（30%对17%；P = 0.04）。此外，对照组也更有可能经历肠道QOL（21%对5%；P = 0.02）和尿QOL（23%对8%；P = 0.02）的大幅下降（MID的两倍）。
水凝胶间隔物在前列腺癌图像引导调强放射治疗后降低直肠剂量、毒性和QOL下降方面的益处随着随访期延长得以维持或增加，为水凝胶间隔物在前列腺放射治疗中的应用益处提供了更有力的证据。
