Kishan Amar U, Wang Pin-Chieh, Upadhyaya Shrinivasa K, Hauswald Henrik, Demanes D Jeffrey, Nickols Nicholas G, Kamrava Mitchell, Sadeghi Ahmad, Kupelian Patrick A, Steinberg Michael L, Prionas Nicolas D, Buyyounouski Mark K, King Christopher R
Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California.
Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California.
Pract Radiat Oncol. 2016 Jul-Aug;6(4):268-275. doi: 10.1016/j.prro.2015.11.002. Epub 2015 Nov 10.
To compare patterns of prostate-specific antigen (PSA) response following stereotactic body radiation therapy (SBRT), high-dose-rate (HDR) brachytherapy, and conventionally fractionated intensity modulated radiation therapy (IMRT) in patients with low- or intermediate-risk prostate cancer (CaP).
Eligible study patients included 439 patients with low- or intermediate-risk prostate cancer who were treated with radiation therapy (RT) alone between 2003 and 2013, remained free of biochemical recurrence, and had at least 2 PSA values within the first year following RT. Of these, 130 were treated with SBRT, 220 with HDR brachytherapy, and 89 with IMRT. Multivariate regression analysis was used to compare PSA nadirs (nPSA), time to nPSA, and PSA bounce parameters among the 3 modalities. Indicator variable analysis was used to develop empirical models of PSA decay using the treatment modalities as indicator variables.
Significantly more patients treated with SBRT or HDR brachytherapy achieved raw nPSAs of <0.5 ng/mL compared with patients treated with IMRT (76.2% and 75.9% vs 44.9%, respectively; P < .0001 for SBRT or HDR brachytherapy vs IMRT). On multivariate analysis, nPSA was significantly lower with SBRT and HDR compared with IMRT (P < .0001). Time to nPSA and bounce parameters was not significantly different among IMRT, SBRT, and HDR. Overall, SBRT and HDR brachytherapy caused significantly larger PSA decay rates (P < .001). When truncating follow-up at 1000 days, the corresponding decay rates were larger for all 3 modalities, with no significant differences between them.
Stereotactic body radiation therapy and HDR brachytherapy produce lower nPSAs than IMRT. Within 1000 days of follow-up, the modalities produce similar rates of PSA decay; subsequently, decay continues (albeit at a slower pace) after SBRT and HDR brachytherapy but plateaus with IMRT. Because nPSA is a validated predictor of long-term outcome, these data not only suggest a distinct radiobiological effect with SBRT and HDR brachytherapy, but also predict for clinical outcomes that might equal or surpass those of IMRT.
比较立体定向体部放射治疗（SBRT）、高剂量率（HDR）近距离放射治疗和常规分割调强放射治疗（IMRT）用于低危或中危前列腺癌（CaP）患者后的前列腺特异性抗原（PSA）反应模式。
符合条件的研究患者包括439例在2003年至2013年间接受单纯放射治疗（RT）、无生化复发且在RT后第一年至少有2个PSA值的低危或中危前列腺癌患者。其中，130例接受SBRT治疗，220例接受HDR近距离放射治疗，89例接受IMRT治疗。采用多因素回归分析比较三种治疗方式的PSA最低点（nPSA）、达到nPSA的时间和PSA反弹参数。使用指标变量分析，以治疗方式作为指标变量建立PSA衰减的经验模型。
与接受IMRT治疗的患者相比，接受SBRT或HDR近距离放射治疗的患者达到原始nPSA<0.5 ng/mL的比例显著更高（分别为76.2%和75.9%对44.9%；SBRT或HDR近距离放射治疗与IMRT相比，P<.0001）。多因素分析显示，与IMRT相比，SBRT和HDR的nPSA显著更低（P<.0001）。IMRT、SBRT和HDR之间达到nPSA的时间和反弹参数无显著差异。总体而言，SBRT和HDR近距离放射治疗导致的PSA衰减率显著更大（P<.001）。当将随访截断在1000天时，所有三种治疗方式的相应衰减率均更大，且它们之间无显著差异。
立体定向体部放射治疗和HDR近距离放射治疗产生的nPSA低于IMRT。在随访的1000天内，这些治疗方式产生的PSA衰减率相似；随后，SBRT和HDR近距离放射治疗后衰减继续（尽管速度较慢），而IMRT则趋于平稳。由于nPSA是长期预后的有效预测指标，这些数据不仅提示SBRT和HDR近距离放射治疗具有独特的放射生物学效应，还预测了可能等同于或超过IMRT的临床结局。
