Department of Radiation Oncology, City of Hope National Medical Center, Duarte, California.
Department of Biostatistics, City of Hope National Medical Center, Duarte, California.
Pract Radiat Oncol. 2021 Jan-Feb;11(1):e90-e97. doi: 10.1016/j.prro.2020.06.004. Epub 2020 Jun 18.
Our purpose was to analyze dose-volume parameters associated with genitourinary (GU) toxicity from a phase I clinical trial of prostate bed stereotactic body radiation therapy.
Patients were treated in escalating dose levels of 35, 40, and 45 Gy, over 5 fractions. Data from all 26 patients enrolled in the protocol were analyzed using multiple dose-volume cut points for multiple GU organs at risk. Univariate logistical regression and Fisher exact test were used to assess statistical significance associated with incidence of toxicity.
The median follow-up was 36 months for all patients. Acute GU toxicity was mild and resolved spontaneously. Eight out of 26 patients (30.7%) developed late GU toxicity of grade 2 or higher. Two patients developed grade 3 ureteral stenosis, 1 in the 35 Gy arm and the other in the 45 Gy arm. Three patients developed grade 2 or higher hematuria/cystitis, and 3 developed grade 2 or higher incontinence. Incidence of grade 3 ureteral stenosis was related to the absolute volume of bladder wall receiving greater than 20, 25, and 30 Gy (P < .01). Grade 2 cystitis and hematuria were related to the volume of bladder wall receiving 20 Gy less than 34% and 35 Gy less than 25% (18.8% vs 60% and 23.8% vs 80%, respectively, P < .05). Incontinence was related to mean urethral dose less than 35 Gy and 25 Gy (4.3% vs 66.7% and 0% vs 37.5%, respectively, P < .05) and volume of urethra receiving 35 Gy less than 24% (8.3% vs 50%, P < .05).
This is the first analysis to report dose-volume thresholds associated with late GU toxicity in patients receiving prostate bed stereotactic body radiation therapy. We recommend limiting the bladder wall receiving 25 Gy to less than 18 cubic centimeters to reduce the risk for late grade 3 ureteral stenosis.
本研究旨在分析前列腺床立体定向体部放射治疗的 I 期临床试验中与泌尿生殖系统（GU）毒性相关的剂量-体积参数。
患者在 5 个分次中分别接受 35、40 和 45 Gy 的递增剂量水平治疗。使用多个危及 GU 器官的剂量-体积截断值对协议中纳入的所有 26 例患者的数据进行分析。采用单变量逻辑回归和 Fisher 确切检验评估与毒性发生相关的统计学意义。
所有患者的中位随访时间为 36 个月。急性 GU 毒性轻微，可自行缓解。26 例患者中有 8 例（30.7%）发生 2 级或以上晚期 GU 毒性。2 例患者发生 3 级输尿管狭窄，1 例发生在 35 Gy 组，另 1 例发生在 45 Gy 组。3 例患者发生 2 级或以上血尿/膀胱炎，3 例患者发生 2 级或以上尿失禁。3 级输尿管狭窄的发生率与膀胱壁接受大于 20、25 和 30 Gy 的绝对体积相关（P <.01）。2 级膀胱炎和血尿与膀胱壁接受 20 Gy 的体积小于 34%和 35 Gy 的体积小于 25%相关（分别为 18.8%对 60%和 23.8%对 80%，P <.05）。尿失禁与平均尿道剂量小于 35 Gy 和 25 Gy（分别为 4.3%对 66.7%和 0%对 37.5%，P <.05）和接受 35 Gy 的尿道体积小于 24%相关（8.3%对 50%，P <.05）。
这是首次报道接受前列腺床立体定向体部放射治疗的患者发生晚期 GU 毒性的剂量-体积阈值的分析。我们建议将接受 25 Gy 的膀胱壁体积限制在 18 立方厘米以下，以降低晚期 3 级输尿管狭窄的风险。
