Jaccard Maud, Zilli Thomas, Dubouloz Angèle, Escude Lluís, Jorcano Sandra, Linthout Nadine, Bral Samuel, Verbakel Wilko, Bruynzeel Anna, Björkqvist Mikko, Minn Heikki, Tsvang Lev, Symon Zvi, Lencart Joana, Oliveira Angelo, Ozen Zeynep, Abacioglu Ufuk, Pérez-Moreno Juan María, Rubio Carmen, Rouzaud Michel, Miralbell Raymond
Radiation Oncology, University Hospital of Geneva, Geneva, Switzerland.
Radiation Oncology, University Hospital of Geneva, Geneva, Switzerland; Faculty of Medicine, Geneva University, Geneva, Switzerland.
Int J Radiat Oncol Biol Phys. 2020 Nov 15;108(4):1047-1054. doi: 10.1016/j.ijrobp.2020.06.002. Epub 2020 Jun 12.
To present the radiation therapy quality assurance results from a prospective multicenter phase 2 randomized trial of short versus protracted urethra-sparing stereotactic body radiation therapy (SBRT) for localized prostate cancer.
Between 2012 and 2015, 165 patients with prostate cancer from 9 centers were randomized and treated with SBRT delivered either every other day (arm A, n = 82) or once a week (arm B, n = 83); 36.25 Gy in 5 fractions were prescribed to the prostate with (n = 92) or without (n = 73) inclusion of the seminal vesicles (SV), and the urethra planning-risk volume received 32.5 Gy. Patients were treated either with volumetric modulated arc therapy (VMAT; n = 112) or with intensity modulated radiation therapy (IMRT; n = 53). Deviations from protocol dose constraints, planning target volume (PTV) homogeneity index, PTV Dice similarity coefficient, and number of monitor units for each treatment plan were retrospectively analyzed. Dosimetric results of VMAT versus IMRT and treatment plans with versus without inclusion of SV were compared.
At least 1 major protocol deviation occurred in 51 patients (31%), whereas none was observed in 41. Protocol violations were more frequent in the IMRT group (P < .001). Furthermore, the use of VMAT yielded better dosimetric results than IMRT for urethra planning-risk volume D (31.1 vs 30.8 Gy, P < .0001), PTV D (37.9 vs 38.7 Gy, P < .0001), homogeneity index (0.09 vs 0.10, P < .0001), Dice similarity coefficient (0.83 vs 0.80, P < .0001), and bladder wall V (24.5% vs 33.5%, P = .0001). To achieve its goals volumetric modulated arc therapy required fewer monitor units than IMRT (2275 vs 3378, P <.0001). The inclusion of SV in the PTV negatively affected the rectal wall V (9.1% vs 10.4%, P = .0003) and V (13.2% vs 15.7%, P = .0003).
Protocol deviations with potential impact on tumor control or toxicity occurred in 31% of patients in this prospective clinical trial. Protocol deviations were more frequent with IMRT. Prospective radiation therapy quality assurance protocols should be strongly recommended for SBRT trials to minimize potential protocol deviations.
展示一项前瞻性多中心2期随机试验的放射治疗质量保证结果，该试验比较了短疗程与延长疗程的保尿道立体定向体部放射治疗（SBRT）用于局限性前列腺癌的疗效。
2012年至2015年期间，来自9个中心的165例前列腺癌患者被随机分组，并接受SBRT治疗，隔日治疗一次（A组，n = 82）或每周治疗一次（B组，n = 83）；前列腺处方剂量为36.25 Gy分5次给予，其中92例患者的计划靶体积（PTV）包括精囊（SV），73例患者不包括精囊，尿道计划危及器官体积接受32.5 Gy。患者接受容积调强弧形放疗（VMAT；n = 112）或调强放射治疗（IMRT；n = 53）。回顾性分析每个治疗计划与方案剂量约束的偏差、PTV均匀性指数、PTV骰子相似系数和监测单位数量。比较VMAT与IMRT的剂量学结果以及包含与不包含SV的治疗计划。
51例患者（31%）至少发生1次主要方案偏差，而41例患者未观察到偏差。IMRT组方案违规更频繁（P <.001）。此外，对于尿道计划危及器官体积D（31.1 vs 30.8 Gy，P <.0001）、PTV D（37.9 vs 38.7 Gy，P <.0001）、均匀性指数（0.09 vs 0.10，P <.0001）、骰子相似系数（0.83 vs 0.80，P <.0001）和膀胱壁V（24.5% vs 33.5%，P =.0001），VMAT的剂量学结果优于IMRT。为达到目标，VMAT所需的监测单位比IMRT少（2275 vs 3378，P <.0001）。PTV中包含SV对直肠壁V（9.1% vs 10.4%，P =.0003）和V（13.2% vs 15.7%，P =.0003）有负面影响。
在这项前瞻性临床试验中，31%的患者出现了可能影响肿瘤控制或毒性的方案偏差。IMRT的方案偏差更频繁。强烈建议在SBRT试验中采用前瞻性放射治疗质量保证方案，以尽量减少潜在的方案偏差。
