BACKGROUND AND PURPOSE High dose-rate (HDR) brachytherapy as monotherapy is a treatment option for localized prostate cancer, but optimal dose and fractionation is unknown. We report efficacy results of a randomized phase II trial of HDR monotherapy delivered as either one or two fractions. MATERIALS AND METHODS Eligible patients had low or intermediate risk prostate cancer, prostate volume <60 cc, and no androgen deprivation use. 170 patients were randomized to receive HDR as either a single fraction of 19 Gy or as two fractions of 13.5 Gy one week apart. Median age was 65 years, median PSA was 6.33 ng/ml, and Grade Group 1, 2 and 3 was present in 28%, 60%, and 12%, respectively. There was no difference in baseline factors between arms and 19%, 51% and 30% had low risk, favourable intermediate and unfavourable intermediate risk disease, respectively. The Phoenix definition was used to define biochemical failure, all local failures were confirmed by biopsy and toxicity was assessed using CTCAE v.4. RESULTS Median follow-up was 60 months. PSA decreased more quickly in the 2-fraction arm (p = 0.009). Median PSA at 5-years was 0.65 ng/ml in the single fraction and 0.16 ng/ml in the 2-fraction arm. The 5-year biochemical disease-free survival and cumulative incidence of local failure was 73.5% and 29% in the single fraction arm and 95% (p = 0.001) and 3% (p < 0.001) in the 2-fraction arm, respectively. Recurrence was not associated with initial stage, grade group, or risk group. Grade 2 late rectal toxicity occurred in 1% while the incidence of grade 2 and 3 urinary toxicity was 45% and 1%, respectively, with no difference between arms. CONCLUSIONS HDR monotherapy delivered as two fraction of 13.5 Gy is well tolerated with a high cancer control rate at 5 years. Single fraction monotherapy is inferior and should not be used.

中文翻译：

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前列腺高剂量率近距离放射治疗作为中低风险前列腺癌的单一疗法：疗效来自一项随机 II 期临床试验，一次 19 Gy 或两次 13.5 Gy

背景和目的 高剂量率 (HDR) 近距离放射疗法作为单一疗法是局部前列腺癌的一种治疗选择，但最佳剂量和分割尚不清楚。我们报告了 HDR 单一疗法的随机 II 期试验的疗效结果，该试验以一次或两次的形式提供。材料和方法 符合条件的患者患有低危或中危前列腺癌，前列腺体积 <60 cc，且未使用雄激素剥夺。170 名患者随机接受 HDR 治疗，分别接受 19 Gy 的单次照射或间隔一周的两次 13.5 Gy 照射。中位年龄为 65 岁，中位 PSA 为 6.33 ng/ml，级别组 1、2 和 3 分别为 28%、60% 和 12%。两组之间的基线因素没有差异，19%，51% 和 30% 患有低风险、有利的中危疾病和不利的中危疾病，分别。Phoenix 定义用于定义生化失败，所有局部失败均通过活检确认，并使用 CTCAE v.4 评估毒性。结果 中位随访时间为 60 个月。PSA 在 2 组分组中下降得更快（p = 0.009）。5 年的 PSA 中位数在单一组分中为 0.65 ng/ml，在 2 组分组中为 0.16 ng/ml。5 年生化无病生存率和局部失败累积发生率在单次组中分别为 73.5% 和 29%，在 2 次组中分别为 95% (p = 0.001) 和 3% (p < 0.001) . 复发与初始阶段、等级组或风险组无关。2 级晚期直肠毒性发生率为 1%，而 2 级和 3 级泌尿毒性的发生率分别为 45% 和 1%，两组之间没有差异。结论 HDR 单一疗法作为 13.5 Gy 的两个部分提供，耐受性良好，5 年癌症控制率高。单次单一疗法较差，不应使用。