Sunnybrook Health Sciences Centre-Odette Cancer Centre, Toronto, Canada; Department of Radiation Oncology, University of Toronto, Toronto, Canada; Division of Radiation Oncology, College of Medicine, King Saud University, Riyadh, Saudi Arabia.
Sunnybrook Health Sciences Centre-Odette Cancer Centre, Toronto, Canada; Department of Radiation Oncology, University of Toronto, Toronto, Canada; Department of Health Policy, Measurement, and Evaluation, University of Toronto, Toronto, Canada.
Int J Radiat Oncol Biol Phys. 2019 Aug 1;104(5):1066-1073. doi: 10.1016/j.ijrobp.2019.04.006. Epub 2019 Apr 16.
High-dose-rate brachytherapy boost plus external beam radiation therapy is an established option for intermediate-risk prostate cancer (PCa). Stereotactic body radiation therapy (SBRT) boost can potentially mimic high-dose-rate boost and could be a viable alternative. Here we report the long-term outcomes of a phase 1 dose-escalation trial of single-fraction SBRT boost.
Patients had intermediate-risk PCa and were accrued to 3 different SBRT single-fraction dose-level cohorts (10 Gy, 12.5 Gy, and 15 Gy). All received supplemental radiation therapy afterwards (37.5 Gy in 15 fractions). Three gold fiducials were implanted for image guidance. Patients were simulated and treated with a foley catheter and intrarectal balloon. A T2 magnetic resonance imaging scan was used for contouring, and a cine magnetic resonance imaging scan was used to calculate patient-specific internal target volume margins. Toxicity and quality-of-life data were collected using Common Terminology Criteria for Adverse Events v3.0 and the Expanded Prostate Cancer Index Composite.
30 patients were accrued, 10 in each cohort. Median follow-up was 72 months. 60% had unfavorable intermediate-risk PCa. Two patients in the 15 Gy cohort developed late grade ≥3 gastrointestinal and genitourinary toxicity, with 1 patient suffering from a grade-4 rectal fistula after a rectal ulcer was biopsied repeatedly. Two patients had biochemical failure. Median PSA nadir was 0.4 ng/mL with 10 Gy, 0.09 ng/mL with 12.5 Gy and 0.07 ng/mL with 15 Gy. Median PSA at 4 years as well as proportion achieving a nadir <0.2 ng/mL improved significantly with higher doses. There was no significant change in quality of life from baseline in any of the domains, and the minimal clinically important change was not statistically different between the 3 cohorts.
Other than a grade 4 toxicity, which may in part be due to repeated biopsies of a rectal ulcer, single-fraction SBRT boost was feasible and well tolerated. Larger studies are warranted to better document the outcomes of such an approach.
高剂量率近距离放疗加外照射放疗是中危前列腺癌（PCa）的一种既定选择。立体定向体部放疗（SBRT）加量有可能模拟高剂量率加量，并且可能是一种可行的替代方法。在此，我们报告一项单剂量 SBRT 加量的 1 期剂量递增试验的长期结果。
患者患有中危 PCa，并被纳入 3 个不同的 SBRT 单剂量水平队列（10 Gy、12.5 Gy 和 15 Gy）。所有患者随后均接受补充放疗（15 个分次 37.5 Gy）。为图像引导植入了 3 个金基准点。患者接受 Foley 导管和直肠内球囊模拟和治疗。使用 T2 磁共振成像扫描进行轮廓勾画，并使用电影磁共振成像扫描计算患者特定的内靶区边界。使用常见不良事件术语标准 v3.0 和扩展前列腺癌指数综合量表收集毒性和生活质量数据。
共纳入 30 例患者，每个队列 10 例。中位随访时间为 72 个月。60%的患者患有不利的中危 PCa。15 Gy 队列中有 2 例患者发生晚期≥3 级胃肠道和泌尿生殖系统毒性，其中 1 例患者在直肠溃疡反复活检后发生 4 级直肠瘘。2 例患者发生生化失败。10 Gy 组中位 PSA 最低点为 0.4 ng/mL，12.5 Gy 组为 0.09 ng/mL，15 Gy 组为 0.07 ng/mL。10 Gy 组、12.5 Gy 组和 15 Gy 组 4 年时 PSA 中位数以及达到 PSA 最低点<0.2 ng/mL 的比例均显著提高。在任何一个领域，与基线相比，生活质量均无明显变化，并且 3 个队列之间的最小临床重要差异无统计学意义。
除 1 例 4 级毒性外（可能部分归因于直肠溃疡的多次活检），单剂量 SBRT 加量是可行的且耐受良好。需要更大的研究来更好地记录这种方法的结果。
