BACKGROUND AND PURPOSE While favourable long-term outcomes have been reported in organ-confined prostate cancer treated with 5 × 7-8 Gy extreme hypofractionation, dose escalation to 5 × 9-10 Gy improved local control but was associated with unacceptable rates of late rectal and urinary toxicities. The purpose of this study was to explore the feasibility of intra-fractional prostate immobilization in reducing toxicity, to promote dose escalation with extreme hypofractionated radiotherapy in prostate cancer. MATERIAL AND METHODS 207 patients received 5 consecutive fractions of 9 Gy. An air-inflated (150 cm3) endorectal balloon and an intraurethral Foley catheter with 3 beacon transponders were used to immobilize the prostate and monitor intra-fractional target motion. VMAT-IGRT with inverse dose-painting was employed in delivering the PTV dose and in sculpting exposure of normal organs at risk to fulfil dose-volume constraints. RESULTS Introduction of air-filled balloon induced repeatable rectum/prostate complex migration from its resting position to a specific retropubic niche, affording the same 3D anatomical configuration daily. Intra-fractional target deviations ≤1 mm occurred in 95% of sessions, while target realignment in ≥2 mm deviations enabled treatment completion as scheduled. Nadir PSA at median 54 months follow-up was 0.19 ng/mL, and bRFS was 100%, 92.4% and 71.4% in low-, intermediate- and high-risk categories, respectively. Late Grade 2 GU and GI toxicities were 2.9% and 2.4%, respectively. No adverse changes in patient-reported quality of life scores were observed. CONCLUSION The unique spatial configuration of this prostate motion mitigation protocol enabled precise treatment planning and delivery that optimized outcomes of ultra-high 5 × 9 Gy hypofractionated radiotherapy of organ-confined prostate cancer.

中文翻译：

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目标运动缓解促进高精度治疗计划和极端大分割前列腺癌放射治疗的实施：来自 II 期研究的结果

背景和目的 虽然已经报道了用 5 × 7-8 Gy 极端大分割治疗的器官局限型前列腺癌有良好的长期结果，但剂量增加到 5 × 9-10 Gy 改善了局部控制，但与不可接受的晚期直肠癌发生率相关。和泌尿系统毒性。本研究的目的是探索分次内固定前列腺在降低毒性方面的可行性，以促进前列腺癌极端大分割放疗的剂量递增。材料和方法 207 名患者接受了 5 次连续分次 9 Gy。充气 (150 cm3) 直肠内球囊和带有 3 个信标转发器的尿道内 Foley 导管用于固定前列腺并监测分次内目标运动。具有反向剂量绘制的 VMAT-IGRT 用于提供 PTV 剂量和雕​​刻有风险的正常器官的暴露，以满足剂量-体积限制。结果 充气球囊的引入诱导可重复的直肠/前列腺复合体从其静止位置迁移到特定的耻骨后壁龛，每天提供相同的 3D 解剖结构。95% 的疗程中发生了≤1 毫米的分数内目标偏差，而 ≥2 毫米偏差的目标重新调整使治疗能够按计划完成。中位 54 个月随访时的最低点 PSA 为 0.19 ng/mL，低、中和高风险类别的 bRFS 分别为 100%、92.4% 和 71.4%。晚期 2 级 GU 和 GI 毒性分别为 2.9% 和 2.4%。没有观察到患者报告的生活质量评分出现不利变化。