Koroulakis Antony, Molitoris Jason, Kaiser Adeel, Hanna Nader, Bafford Andrea, Jiang Yixing, Bentzen Søren, Regine William F
University of Maryland Medical Center, Radiation Oncology, Baltimore, Maryland.
University of Maryland School of Medicine, Radiation Oncology, Baltimore, Maryland.
Adv Radiat Oncol. 2020 Oct 14;6(1):100595. doi: 10.1016/j.adro.2020.10.008. eCollection 2021 Jan-Feb.
Reirradiation for rectal cancer (RC) after prior pelvic radiation therapy (RT) has been shown to be safe and effective. However, limited data exist for proton therapy (PT), including pencil beam scanning proton therapy (PBS-PT). We hypothesize that PT is safe and feasible for re-treatment and may allow for decreased toxicity and treatment escalation.
A single-institution, retrospective, institutional review board-approved analysis of all patients with RC and prior pelvic RT receiving PBS-PT reirradiation was performed. Data on patient and treatment characteristics and outcomes were collected. Local progression, progression-free survival, overall survival, and late grade >3 toxicity were estimated using the Kaplan-Meier method.
Twenty-eight patients (median follow-up: 28.6 months) received PBS-PT reirradiation between 2016 and 2019, including 18 patients with recurrent RC (median prior dose: 54.0 Gy) and 10 patients with de novo RC and variable prior RT. The median reirradiation dose was 44.4 Gy (range, 16.0-60.0 Gy; 21 of 28 twice daily), and 24 of 28 patients received concurrent chemotherapy. Six underwent surgical resection. Three (10.7%) experienced grade 3 acute toxicities, and 1 did not complete RT owing to toxicity. Four (14.2%) had late grade <3 toxicity, including 1 grade 5 toxicity in a patient with a prior RT-related injury. The 1-year local progression, progression-free survival, and overall survival rates were 33.7% (95% confidence interval [CI], 14.5%-52.9%), 45.0% (95% CI, 26.2%-63.8%), and 81.8% (95% CI, 67.3%-96.3%), respectively.
This is the largest series using PT for reirradiation for RC and the first study using PBS-PT. Low acute toxicity rates and acceptable late toxicity support PBS-PT as an option for this high-risk patient population, with a need for continued follow-up.
先前盆腔放射治疗（RT）后直肠癌（RC）再程放疗已被证明是安全有效的。然而，关于质子治疗（PT）的数据有限，包括笔形束扫描质子治疗（PBS-PT）。我们假设PT用于再治疗是安全可行的，并且可能降低毒性并允许提高治疗强度。
对所有接受PBS-PT再程放疗的RC患者和先前盆腔RT患者进行了一项单机构、回顾性、经机构审查委员会批准的分析。收集了患者、治疗特征和结果的数据。使用Kaplan-Meier方法估计局部进展、无进展生存期、总生存期和晚期3级以上毒性。
2016年至2019年间，28例患者（中位随访时间：28.6个月）接受了PBS-PT再程放疗，其中18例为复发性RC患者（先前中位剂量：54.0 Gy），10例为初发性RC患者且先前RT剂量各异。再程放疗的中位剂量为44.4 Gy（范围，16.0 - 60.0 Gy；28例中有21例每天两次），28例患者中有24例接受了同步化疗。6例接受了手术切除。3例（10.7%）出现3级急性毒性，1例因毒性未完成放疗。4例（14.2%）出现晚期3级以下毒性，包括1例先前有RT相关损伤患者出现5级毒性。1年局部进展率、无进展生存率和总生存率分别为33.7%（95%置信区间[CI]，14.5% - 52.9%）、45.0%（95% CI，26.2% - 63.8%）和81.8%（95% CI，67.3% - 96.3%）。
这是使用PT进行RC再程放疗的最大系列研究，也是使用PBS-PT的第一项研究。低急性毒性率和可接受的晚期毒性支持将PBS-PT作为该高危患者群体的一种选择，需要持续随访。
