Shima Satoshi, Takakusagi Yosuke, Okuda Tatsuya, Koge Hiroaki, Kano Kio, Okada Kohei, Tsuchida Keisuke, Kawashiro Shohei, Mizoguchi Nobutaka, Yoshida Daisaku, Katoh Hiroyuki, Uno Takashi
Department of Radiation Oncology, Kanagawa Cancer Center, Yokohama, Kanagawa, Japan.
Diagnostic Radiology and Radiation Oncology, Graduate School of Medicine, Chiba University, Chiba, Chiba, Japan.
Cancers (Basel). 2025 Aug 31;17(17):2867. doi: 10.3390/cancers17172867.
Biochemical recurrence after radiotherapy for prostate cancer is commonly defined by the Phoenix criteria (prostate-specific antigen [PSA] nadir + 2 ng/mL). However, some patients experience PSA elevation without clinical recurrence, which is known as PSA bounce. This study aimed to evaluate PSA kinetics after scanning-method carbon ion radiotherapy (CIRT) in patients with high-risk prostate cancer (HR-PCa) and to assess the clinical validity of the Phoenix criteria. We retrospectively analyzed 171 patients with HR-PCa who underwent CIRT and 2 years of androgen deprivation therapy. Patients were classified into three groups based on post-treatment PSA kinetics: non-recurrence, pseudo-recurrence (PR; PSA > 2 ng/mL followed by spontaneous decline without salvage therapy), and recurrence (R; PSA > 2 ng/mL with salvage therapy). PSA bounce was defined as a transient PSA increase > 0.4 ng/mL followed by spontaneous decline. Kaplan-Meier and receiver operating characteristic (ROC) analyses were used to evaluate biochemical relapse-free survival and determine the optimal PSA cutoff. Among 171 patients, 18 (10.5%) met the Phoenix criteria (R+PR), of whom 6 (33.3%) experienced spontaneous PSA decline. The 5-year biochemical relapse-free survival rate was 90.0%. PSA bounce occurred in 33.9%. ROC analysis identified an optimal PSA cutoff of 1.91 ng/mL (area under the curve: 0.985), whereas the positive predictive value at the 2 ng/mL cutoff was as low as 61.1% due to the influence of PSA bounce. After CIRT, a PSA rise of >2 ng/mL does not always indicate HR-PCa recurrence and should be interpreted with caution to avoid overtreatment.
前列腺癌放疗后的生化复发通常根据凤凰标准（前列腺特异性抗原[PSA]最低点+2 ng/mL）来定义。然而，一些患者经历PSA升高但无临床复发，这被称为PSA反弹。本研究旨在评估高危前列腺癌（HR-PCa）患者接受扫描法碳离子放疗（CIRT）后的PSA动力学，并评估凤凰标准的临床有效性。我们回顾性分析了171例接受CIRT和2年雄激素剥夺治疗的HR-PCa患者。根据治疗后PSA动力学将患者分为三组：无复发、假性复发（PR；PSA>2 ng/mL，随后未经挽救治疗自行下降）和复发（R；PSA>2 ng/mL并接受挽救治疗）。PSA反弹定义为PSA短暂升高>0.4 ng/mL，随后自行下降。采用Kaplan-Meier和受试者操作特征（ROC）分析来评估无生化复发生存率并确定最佳PSA临界值。在171例患者中，18例（10.5%）符合凤凰标准（R+PR），其中6例（33.3%）经历了PSA自行下降。5年无生化复发生存率为90.0%。PSA反弹发生率为33.9%。ROC分析确定最佳PSA临界值为1.91 ng/mL（曲线下面积：0.985），而由于PSA反弹的影响，2 ng/mL临界值时的阳性预测值低至61.1%。CIRT后，PSA升高>2 ng/mL并不总是表明HR-PCa复发，应谨慎解读以避免过度治疗。
