Department of Radiation Oncology, University of California, Los Angeles, USA.
UCLA Division of General Internal Medicine and Health Services Research, USA.
Radiother Oncol. 2021 Jan;154:207-213. doi: 10.1016/j.radonc.2020.09.053. Epub 2020 Oct 7.
The optimal dose for prostate stereotactic body radiotherapy (SBRT) is still unknown. This study evaluated the dose-response relationships for prostate-specific antigen (PSA) decay and biochemical recurrence (BCR) among 4 SBRT dose regimens.
In 1908 men with low-risk (50.0%), favorable intermediate-risk (30.9%), and unfavorable intermediate-risk (19.1%) prostate cancer treated with prostate SBRT across 8 institutions from 2003 to 2018, we examined 4 regimens (35 Gy/5 fractions [35/5, n = 265, 13.4%], 36.25 Gy/5 fractions [36.25/5, n = 711, 37.3%], 40 Gy/5 fractions [40/5, n = 684, 35.8%], and 38 Gy/4 fractions [38/4, n = 257, 13.5%]). Between dose groups, we compared PSA decay slope, nadir PSA (nPSA), achievement of nPSA ≤0.2 and ≤0.5 ng/mL, and BCR-free survival (BCRFS).
Median follow-up was 72.3 months. Median nPSA was 0.01 ng/mL for 38/4, and 0.17-0.20 ng/mL for 5-fraction regimens (p < 0.0001). The 38/4 cohort demonstrated the steepest PSA decay slope and greater odds of nPSA ≤0.2 ng/mL (both p < 0.0001 vs. all other regimens). BCR occurred in 6.25%, 6.75%, 3.95%, and 8.95% of men treated with 35/5, 36.25/5, 40/5, and 38/4, respectively (p = 0.12), with the highest BCRFS after 40/5 (vs. 35/5 hazard ratio [HR] 0.49, p = 0.026; vs. 36.25/5 HR 0.42, p = 0.0005; vs. 38/4 HR 0.55, p = 0.037) including the entirety of follow-up, but not for 5-year BCRFS (≥93% for all regimens, p ≥ 0.21).
Dose-escalation was associated with greater prostate ablation and PSA decay. Dose-escalation to 40/5, but not beyond, was associated with improved BCRFS. Biochemical control remains excellent, and prospective studies will provide clarity on the benefit of dose-escalation.
前列腺立体定向体放射治疗（SBRT）的最佳剂量仍不清楚。本研究评估了 4 种 SBRT 剂量方案中前列腺特异性抗原（PSA）下降和生化复发（BCR）的剂量反应关系。
在 1908 名低危（50.0%）、中危有利（30.9%）和中危不利（19.1%）前列腺癌患者中，我们检查了 4 种方案（35 Gy/5 个剂量[35/5，n=265，13.4%]、36.25 Gy/5 个剂量[36.25/5，n=711，37.3%]、40 Gy/5 个剂量[40/5，n=684，35.8%]和 38 Gy/4 个剂量[38/4，n=257，13.5%]）。在剂量组之间，我们比较了 PSA 下降斜率、最低 PSA（nPSA）、达到 nPSA≤0.2 和 nPSA≤0.5ng/ml 以及 BCR 无复发生存率（BCRFS）。
中位随访时间为 72.3 个月。对于 38/4 方案，中位 nPSA 为 0.01ng/ml，而 5 个剂量方案的 nPSA 为 0.17-0.20ng/ml（均<0.0001）。38/4 组的 PSA 下降斜率最陡，达到 nPSA≤0.2ng/ml 的可能性也更大（均<0.0001，与所有其他方案相比）。35/5、36.25/5、40/5 和 38/4 方案治疗的男性中，分别有 6.25%、6.75%、3.95%和 8.95%发生 BCR（p=0.12），40/5 方案的 BCRFS 最高（与 35/5 相比，HR 0.49，p=0.026；与 36.25/5 相比，HR 0.42，p=0.0005；与 38/4 相比，HR 0.55，p=0.037），包括整个随访期，但 5 年 BCRFS 并非如此（所有方案均≥93%，p≥0.21）。
剂量递增与更大的前列腺消融和 PSA 下降有关。递增剂量至 40/5，但不超过，与改善 BCRFS 相关。生化控制仍然非常好，前瞻性研究将阐明剂量递增的益处。
