Department of Radiation Oncology, University of Washington, Seattle, Washington.
Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts.
Int J Radiat Oncol Biol Phys. 2020 Nov 1;108(3):635-643. doi: 10.1016/j.ijrobp.2020.01.026. Epub 2020 Feb 6.
Our purpose was to compare dosimetric parameters and late gastrointestinal outcomes between patients treated with proton beam therapy (PBT) for localized prostate cancer with rectal balloon immobilization versus a hydrogel rectal spacer.
Patients with localized, clinical stage T1-4 prostate adenocarcinoma were treated at a single institution using conventionally fractionated, dose-escalated PBT from 2013 to 2018. Patient-reported gastrointestinal toxicity was prospectively collected, and the incidence of rectal bleeding was retrospectively reviewed from patient records.
One hundred ninety-two patients were treated with rectal balloon immobilization, and 75 were treated with a rectal spacer. Rectal hydrogel spacer significantly improved rectal dosimetry while maintaining excellent target coverage. The 2-year actuarial rate of grade 2+ late rectal bleeding was 19% and 3% in the rectal balloon and hydrogel spacer groups, respectively (P = .003). In univariable analysis, the probability of grade 2+ rectal bleeding was significantly correlated with increasing rectal dose. In multivariable analysis, only receipt of spacer hydrogel (hazard ratio, 0.145; P = .010) and anticoagulation use (hazard ratio, 5.019; P < .001) were significantly associated with grade 2+ bleeding. At 2-year follow-up, patient-reported Expanded Prostate Cancer Index Composite bowel quality of life composite scores were less diminished in the hydrogel spacer group (absolute mean difference, 5.5; P = .030).
Use of rectal hydrogel spacer for prostate PBT is associated with a significantly lower incidence of clinically relevant, late rectal bleeding and lower decrement in long-term, patient-reported bowel quality of life compared with rectal balloon immobilization. Our results suggest that hydrogel spacer may improve rectal sparing compared with rectal balloon immobilization during PBT for prostate cancer.
本研究旨在比较接受局部前列腺癌质子束治疗（PBT）的患者中，使用直肠气囊固定与水凝胶直肠间隔器的患者之间的剂量学参数和晚期胃肠道结局。
2013 年至 2018 年，在一家机构中对患有局限性临床 T1-4 前列腺腺癌的患者进行了常规分割、剂量递增的 PBT 治疗。前瞻性收集患者报告的胃肠道毒性数据，并从患者记录中回顾性审查直肠出血的发生率。
192 例患者接受直肠气囊固定，75 例患者接受直肠间隔器治疗。直肠水凝胶间隔器显著改善了直肠剂量学，同时保持了优异的靶区覆盖。直肠气囊和水凝胶间隔器组 2 年晚期直肠出血 2+级的累积发生率分别为 19%和 3%（P=0.003）。单变量分析显示，2+级直肠出血的概率与直肠剂量的增加显著相关。多变量分析显示，仅使用间隔器水凝胶（风险比，0.145；P=0.010）和抗凝药物使用（风险比，5.019；P<0.001）与 2+级出血显著相关。在 2 年随访时，水凝胶间隔器组的患者报告的前列腺癌指数综合（Expanded Prostate Cancer Index Composite，EPIC）排便生活质量综合评分降低幅度较小（绝对平均差异，5.5；P=0.030）。
与直肠气囊固定相比，在前列腺 PBT 中使用直肠水凝胶间隔器与更显著的临床相关晚期直肠出血发生率较低以及长期患者报告的排便生活质量下降幅度较小相关。我们的结果表明，与直肠气囊固定相比，水凝胶间隔器在前列腺癌 PBT 中可能会改善直肠的保护。
