Anwar Mekhail, Weinberg Vivian, Chang Albert J, Hsu I-Chow, Roach Mack, Gottschalk Alexander
Department of Radiation Oncology, University of California San Francisco, Helen Diller Comprehensive Cancer Center, 1600 Divisadero St, Suite H1031, Box 1708, San Francisco, CA 94143-1708, USA.
Radiat Oncol. 2014 Feb 2;9:42. doi: 10.1186/1748-717X-9-42.
Patients with early stage prostate cancer have a variety of curative radiotherapy options, including conventionally-fractionated external beam radiotherapy (CF-EBRT) and hypofractionated stereotactic body radiotherapy (SBRT). Although results of CF-EBRT are well known, the use of SBRT for prostate cancer is a more recent development, and long-term follow-up is not yet available. However, rapid post-treatment PSA decline and low PSA nadir have been linked to improved clinical outcomes. The purpose of this study was to compare the PSA kinetics between CF-EBRT and SBRT in newly diagnosed localized prostate cancer.
MATERIALS/METHODS: 75 patients with low to low-intermediate risk prostate cancer (T1-T2; GS 3 + 3, PSA < 20 or 3 + 4, PSA < 15) treated without hormones with CF-EBRT (>70.2 Gy, <76 Gy) to the prostate only, were identified from a prospectively collected cohort of patients treated at the University of California, San Francisco (1997-2012). Patients were excluded if they failed therapy by the Phoenix definition or had less than 1 year of follow-up or <3 PSAs. 43 patients who were treated with SBRT to the prostate to 38 Gy in 4 daily fractions also met the same criteria. PSA nadir and rate of change in PSA over time (slope) were calculated from the completion of RT to 1, 2 and 3 years post-RT.
The median PSA nadir and slope for CF-EBRT was 1.00, 0.72 and 0.60 ng/ml and -0.09, -0.04, -0.02 ng/ml/month, respectively, for durations of 1, 2 and 3 years post RT. Similarly, for SBRT, the median PSA nadirs and slopes were 0.70, 0.40, 0.24 ng and -0.09, -0.06, -0.05 ng/ml/month, respectively. The PSA slope for SBRT was greater than CF-EBRT (p < 0.05) at 2 and 3 years following RT, although similar during the first year. Similarly, PSA nadir was significantly lower for SBRT when compared to EBRT for years 2 and 3 (p < 0.005).
Patients treated with SBRT experienced a lower PSA nadir and greater rate of decline in PSA 2 and 3 years following completion of RT than with CF-EBRT, consistent with delivery of a higher bioequivalent dose. Although follow-up for SBRT is limited, the improved PSA kinetics over CF-EBRT are promising for improved biochemical control.
早期前列腺癌患者有多种根治性放疗选择，包括常规分割外照射放疗（CF-EBRT）和大分割立体定向体部放疗（SBRT）。虽然CF-EBRT的结果广为人知，但SBRT用于前列腺癌是较新的进展，目前尚无长期随访数据。然而，治疗后PSA快速下降和PSA最低点较低与改善的临床结果相关。本研究的目的是比较新诊断的局限性前列腺癌患者CF-EBRT和SBRT之间的PSA动力学。
材料/方法：从加利福尼亚大学旧金山分校前瞻性收集的一组接受治疗的患者（1997 - 2012年）中，确定75例低至中低风险前列腺癌（T1 - T2；GS 3 + 3，PSA < 20或3 + 4，PSA < 15）患者，仅对前列腺进行无激素的CF-EBRT（>70.2 Gy，<76 Gy）治疗。如果患者根据Phoenix定义治疗失败、随访时间少于1年或PSA检测次数少于3次，则排除该患者。43例接受前列腺SBRT治疗、分4次每日给予38 Gy的患者也符合相同标准。从放疗结束至放疗后1、2和3年计算PSA最低点及PSA随时间的变化率（斜率）。
CF-EBRT放疗后1、2和3年的PSA最低点中位数分别为1.00、0.72和0.60 ng/ml，斜率分别为-0.09、-0.04和-0.02 ng/ml/月。同样，对于SBRT，PSA最低点中位数分别为0.70、0.40和0.24 ng，斜率分别为-0.09、-0.06和-0.05 ng/ml/月。放疗后2年和3年，SBRT的PSA斜率大于CF-EBRT（p < 0.05），尽管第一年两者相似。同样，与EBRT相比，SBRT在第2年和第3年的PSA最低点显著更低（p < 0.005）。
与CF-EBRT相比，接受SBRT治疗的患者在放疗结束后2年和3年的PSA最低点更低，PSA下降率更高，这与给予更高的生物等效剂量一致。虽然SBRT的随访有限，但与CF-EBRT相比，其改善的PSA动力学对于改善生化控制很有前景。
