Jones Ryan T, Hassan Rezaeian Nima, Desai Neil B, Lotan Yair, Jia Xun, Hannan Raquibul, Kim D W Nathan, Hornberger Brad, Dubas Jeffrey, Laine Aaron M, Zelefsky Michael J, Timmerman Robert D, Folkert Michael R
Department of Radiation Oncology, Simmons Comprehensive Cancer Center at the University of Texas Southwestern Medical Center, Dallas, TX, USA.
Department of Radiation Urology, Simmons Comprehensive Cancer Center at the University of Texas Southwestern Medical Center, Dallas, TX, USA.
Med Dosim. 2017;42(4):341-347. doi: 10.1016/j.meddos.2017.07.002. Epub 2017 Jul 31.
This study aimed to compare the rectal-sparing capabilities of rectal balloons vs absorbable injectable spacer gel in stereotactic body radiation therapy (SBRT) for prostate cancer. Patient samples included in this analysis were obtained from 2 multi-institutional prospective trials of SBRT for prostate cancer using a rectal balloon (n = 36 patients) and injectable spacer gel (n = 36). Treatment prescription dose was 45 Gy in 5 fractions in 42 patients; for equal comparison, the remaining 30 patients were rescaled to 45 Gy from 47.5 Gy prescription (n = 6) and 50 Gy prescription (n = 24). The median prostate volumes and body mass index in the 2 patient samples were not statistically significantly different (p= 0.67 and 0.45, respectively), supporting anatomic similarity between cohorts. The injectable spacer gel achieved dosimetric superiority over the rectal balloon with respect to the maximum dose to the rectum (42.3 vs 46.2 Gy, p < 0.001), dose delivered to 33% of the rectal circumference (28 vs 35.1 Gy, p < 0.001), and absolute volume of rectum receiving 45 Gy (V45), V40, and V30 (0.3 vs 1.7 cc, 1 vs 5.4 cc, and 4.1 vs 9.6 cc, respectively; p < 0.001 in all cases). There was no difference between the 2 groups with respect to the V50 of the rectum or the dose to 50% of the rectal circumference (p= 0.29 and 0.06, respectively). The V18.3 of the bladder was significantly larger with the rectal balloon (19.9 vs 14.5 cc, p= 0.003). In this analysis of patients enrolled on 2 consecutive multi-institutional prospective trials of SBRT for prostate cancer, the injectable spacer gel outperformed the rectal balloon in the majority of the examined and relevant dosimetric rectal-sparing parameters. The rectal balloon did not outperform the injectable spacer gel in any measured rectal dose parameter.
本研究旨在比较直肠球囊与可吸收注射式间隔凝胶在前列腺癌立体定向体部放射治疗（SBRT）中对直肠的保护能力。本分析纳入的患者样本来自两项多机构前列腺癌SBRT前瞻性试验，其中一项使用直肠球囊（n = 36例患者），另一项使用注射式间隔凝胶（n = 36）。42例患者的治疗处方剂量为45 Gy，分5次给予；为进行同等比较，其余30例患者的处方剂量从47.5 Gy（n = 6）和50 Gy（n = 24）重新调整为45 Gy。两组患者样本的前列腺体积中位数和体重指数无统计学显著差异（p分别为0.67和0.45），支持两组队列在解剖结构上的相似性。在直肠最大剂量（42.3 vs 46.2 Gy，p < 0.001）、直肠周长33%所接受的剂量（28 vs 35.1 Gy，p < 0.001）以及接受45 Gy（V45）、40 Gy（V40）和30 Gy（V30）的直肠绝对体积方面（分别为0.3 vs 1.7 cc、1 vs 5.4 cc和4.1 vs 9.6 cc；所有情况下p < 0.001），注射式间隔凝胶在剂量学上优于直肠球囊。两组在直肠V50或直肠周长50%所接受的剂量方面无差异（p分别为0.29和0.06）。直肠球囊组的膀胱V18.3显著更大（19.9 vs 14.5 cc，p = 0.003）。在对两项连续的前列腺癌SBRT多机构前瞻性试验纳入患者的分析中，在大多数检查的相关剂量学直肠保护参数方面，注射式间隔凝胶优于直肠球囊。在任何测量的直肠剂量参数中，直肠球囊均未表现优于注射式间隔凝胶。
