Department of Radiation Oncology, Beaumont Health System, Royal Oak, Michigan.
Department of Radiation Oncology, Beaumont Health System, Royal Oak, Michigan.
Int J Radiat Oncol Biol Phys. 2017 May 1;98(1):108-114. doi: 10.1016/j.ijrobp.2017.01.025. Epub 2017 Jan 16.
Prostate-specific antigen (PSA) bounce is a temporary elevation of the PSA level above a prior nadir. The purpose of this study was to determine whether the frequency of a PSA bounce following high-dose-rate (HDR) interstitial brachytherapy for the treatment of prostate cancer is associated with individual treatment fraction size.
Between 1999 and 2014, 554 patients underwent treatment of low- or intermediate-risk prostate cancer with definitive HDR brachytherapy as monotherapy and had ≥3 subsequent PSA measurements. Four different fraction sizes were used: 950 cGy × 4 fractions, 1200 cGy × 2 fractions, 1350 cGy × 2 fractions, 1900 cGy × 1 fraction. Four definitions of PSA bounce were applied: ≥0.2, ≥0.5, ≥1.0, and ≥2.0 ng/mL above the prior nadir with a subsequent return to the nadir.
The median follow-up period was 3.7 years. The actuarial 3-year rate of PSA bounce for the entire cohort was 41.3%, 28.4%, 17.4%, and 6.8% for nadir +0.2, +0.5, +1.0, and +2.0 ng/mL, respectively. The 3-year rate of PSA bounce >0.2 ng/mL was 42.2%, 32.1%, 41.0%, and 59.1% for the 950-, 1200-, 1350-, and 1900-cGy/fraction levels, respectively (P=.002). The hazard ratio for bounce >0.2 ng/mL for patients receiving a single fraction of 1900 cGy compared with those receiving treatment in multiple fractions was 1.786 (P=.024). For patients treated with a single 1900-cGy fraction, the 1-, 2-, and 3-year rates of PSA bounce exceeding the Phoenix biochemical failure definition (nadir +2 ng/mL) were 4.5%, 18.7%, and 18.7%, respectively, higher than the rates for all other administered dose levels (P=.025).
The incidence of PSA bounce increases with single-fraction HDR treatment. Knowledge of posttreatment PSA kinetics may aid in decision making regarding management of potential biochemical failures.
前列腺特异性抗原（PSA）反弹是 PSA 水平在先前最低点之上暂时升高。本研究的目的是确定在接受高剂量率（HDR）间质近距离治疗前列腺癌后，PSA 反弹的频率是否与个体治疗分次剂量大小有关。
1999 年至 2014 年间，554 例低危或中危前列腺癌患者接受单纯 HDR 近距离治疗，并进行了≥3 次后续 PSA 测量。使用了 4 种不同的分次剂量：950cGy×4 分次，1200cGy×2 分次，1350cGy×2 分次，1900cGy×1 分次。应用了 4 种 PSA 反弹定义：较前一最低点升高≥0.2、≥0.5、≥1.0 和≥2.0ng/ml，随后降至最低点。
中位随访时间为 3.7 年。整个队列的 3 年 PSA 反弹发生率分别为 41.3%、28.4%、17.4%和 6.8%，分别为最低点+0.2、+0.5、+1.0 和+2.0ng/ml。3 年 PSA 反弹>0.2ng/ml 的发生率分别为 950-cGy、1200-cGy、1350-cGy 和 1900-cGy/fraction 水平的 42.2%、32.1%、41.0%和 59.1%（P=.002）。与接受多分次治疗的患者相比，接受单次 1900cGy 治疗的患者 PSA 反弹>0.2ng/ml 的风险比为 1.786（P=.024）。对于接受单次 1900cGy 治疗的患者，1、2 和 3 年 PSA 反弹超过 Phoenix 生化失败定义（最低点+2ng/ml）的发生率分别为 4.5%、18.7%和 18.7%，均高于所有其他治疗剂量水平（P=.025）。
PSA 反弹的发生率随着 HDR 单次治疗的增加而增加。了解治疗后 PSA 动力学可能有助于决策潜在生化失败的管理。
