Early and multiple PSA bounces can occur following high-dose prostate stereotactic body radiation therapy: Subset analysis of a phase 1/2 trial

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• 作者：D. Nathan Kim ; MD PhD^a ; ¹ ; Christopher Straka ; MD^b ; ¹ ; L. Chinsoo Cho ; MD^c ; Yair Lotan ; MD^a ; Jingsheng Yan ; PhD^a ; Brian Kavanagh ; MD^d ; David Raben ; MD^d ; Susan Cooley ; RN^a ; Jeffrey Brindle ; MD^e ; Xian Jin Xie ; PhD^a ; David Pistenmaa ; MD ; PhD^a ; Robert Timmerman ; MD^a ; ^{Robert.timmerman@utsouthwestern.edu}
• 刊名：Practical Radiation Oncology
• 出版年：2017
• 出版时间：January-February 2017
• 年：2017
• 卷：7
• 期：1
• 页码：e43-e49
• 全文大小：321 K
• 卷排序：7

文摘

We hypothesized that high-dose stereotactic body radiation therapy (SBRT) would lead to faster time to nadir and lower nadir values compared with conventional radiation therapy experiences. We now report prostate-specific antigen (PSA) kinetics following high-dose SBRT in patients treated with radiation alone.Methods and materialsNinety-one patients were enrolled on the phase 1/2 dose escalation study of SBRT for localized prostate cancer. All patients with at least 36 months of follow-up and without hormone therapy were included in this analysis (n = 47). Treatment response parameters evaluated include time to nadir, nadir value, occurrence of PSA bounces (rise of ≥0.2 ng/mL followed by a subsequent fall), magnitude of bounces, duration of bounces, and correlation of bounces with clinical outcomes.ResultsMedian follow-up was 42 months (range, 36-78 months). Treatment dose levels were 45 Gy (n = 10), 47.5 Gy (n = 8), and 50 Gy (n = 29) in 5 fractions. Biochemical control rate was 98%. Median PSA at follow-up was 0.10 ± 0.20 ng/mL. Median time to nadir was 36 ± 11 months. A total of 24/47 (51.1%) patients had ≥1 PSA bounce. Median magnitude of PSA rise during bounce was 0.50 ± 1.2 ng/mL. Median time to first bounce was 9 ± 7.0 months. Median bounce duration was 3 ± 2.3 months for the first bounce and 6 ± 5.2 months for subsequent bounces. Prostate volumes <30 mL were associated with a decreased likelihood of bounce (P = .0202), and increasing prostate volume correlated with increasingly likelihood of having ≥2 bounces (P = .027). Patients reaching PSA nadir of ≤0.1 ng/mL were less likely to experience any bounce (P = .0044).ConclusionsCompared with other SBRT experiences, our study demonstrated a higher PSA bounce rate, a similar or shorter median time to bounce, and a very low nadir. Prostate volume appears correlated with bounce.