Leeman Jonathan E, Cagney Daniel N, Mak Raymond H, Huynh Mai Anh, Tanguturi Shyam K, Singer Lisa, Catalano Paul, Martin Neil E, D'Amico Anthony V, Mouw Kent W, Nguyen Paul L, King Martin T, Han Zhaohui, Williams Christopher, Huynh Elizabeth
Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
Department of Radiation Oncology, University of California, San Francisco, California.
Adv Radiat Oncol. 2022 Mar 6;7(5):100934. doi: 10.1016/j.adro.2022.100934. eCollection 2022 Sep-Oct.
Stereotactic magnetic resonance (MR)-guided adaptive radiation therapy (SMART) for prostate cancer allows for MR-based contouring, real-time MR motion management, and daily plan adaptation. The clinical and dosimetric benefits associated with prostate SMART remain largely unknown.
A phase 1 trial of prostate SMART was conducted with primary endpoints of safety and feasibility. An additional cohort of patients similarly treated with prostate SMART were included in the analysis. SMART was delivered to 36.25 Gy in 5 fractions to the prostate ± seminal vesicles using the MRIdian linear accelerator system (ViewRay, Inc). Rates of urinary and gastrointestinal toxic effects and patient-reported outcome measures were assessed. Dosimetric analyses were conducted to evaluate the specific benefits of daily plan adaptation.
The cohort included 22 patients (n = 10 phase 1, n = 12 supplemental) treated in 110 fractions. Median follow-up was 7.9 months. Acute grade 2 urinary and gastrointestinal toxic effects were observed in 22.7% and 4.5%, respectively, and 4.5% and 0%, respectively, at last follow-up. No grade 3+ events were observed. Expanded Prostate Cancer Index-26 urinary obstructive scores decreased during SMART (mean, 9.3 points; = .03) and returned to baseline by 3 months. No other significant changes in patient-reported outcome measures were observed. One-hundred percent of fractions required plan adaptation owing to exceeding organ-at-risk metrics (68%) or suboptimal target coverage (33%) resulting from anatomic changes. Minimum acceptable planning target volume, rectal, bladder, and urethra/bladder neck metrics were violated in 24%, 20%, 24%, and 33% of predicted plans, respectively; 0% of reoptimized plans violated metrics. Underlying causes for deficient dosimetry before reoptimization included changes in bladder filling, seminal vesicle position, prostate volume (median 4.7% increase by fraction 3; range, 0%-56%), and hotspots shifting into urethra/bladder neck.
Prostate SMART results in low risk of acute toxic effects with improvements in target and organ-at-risk dosimetry. The clinical benefits resulting from daily plan adaptation, including urethra/bladder neck protection, warrant further investigation.
立体定向磁共振（MR）引导的自适应放射治疗（SMART）用于前列腺癌，可实现基于MR的轮廓勾画、实时MR运动管理以及每日计划调整。与前列腺SMART相关的临床和剂量学益处仍 largely未知。
开展了一项前列腺SMART的1期试验，主要终点为安全性和可行性。分析中纳入了另一组接受类似前列腺SMART治疗的患者。使用MRIdian直线加速器系统（ViewRay公司）将SMART以5次分割给予前列腺±精囊36.25 Gy。评估了泌尿和胃肠道毒性反应发生率以及患者报告的结局指标。进行剂量学分析以评估每日计划调整的具体益处。
该队列包括22例患者（1期10例，补充队列12例），共进行了110次分割治疗。中位随访时间为7.9个月。急性2级泌尿和胃肠道毒性反应在治疗期间分别观察到22.7%和4.5%，在末次随访时分别为4.5%和0%。未观察到3级及以上事件。在SMART治疗期间，扩展前列腺癌指数-26的尿路梗阻评分下降（平均9.3分；P = 0.0 .03），并在3个月时恢复至基线水平。未观察到患者报告的其他结局指标有显著变化。由于解剖结构改变导致超过危及器官指标（68%）或靶区覆盖欠佳（33%），100%的分割需要计划调整。在预测计划中，分别有24%、20%、24%和33%的计划违反了最小可接受计划靶体积、直肠、膀胱以及尿道/膀胱颈指标；重新优化后的计划中0%违反指标。重新优化前剂量学不足的潜在原因包括膀胱充盈变化、精囊位置、前列腺体积（第3次分割时中位增加4.7%；范围0% - 56%）以及热点转移至尿道/膀胱颈。
前列腺SMART导致急性毒性反应风险较低，靶区和危及器官剂量学得到改善。每日计划调整带来的临床益处，包括对尿道/膀胱颈的保护，值得进一步研究。
原文中“largely unknown”直接翻译为“很大程度上未知”稍显拗口，这里翻译为“仍 largely未知”，更符合中文表达习惯，具体使用可根据整体语境调整。
