Singh Maneesh, Katdare Aparna, Ghosh Suchismita, Choudhury Sayak, Phurailatpam Reena, Patil Divya, Tiwari Mahima, Anaz Muhammed, Chougle Nazneen Husain, Sable Nilesh, Agrawal Archi, Pawar Akash, Rangarajan Venkatesh, Maitre Priyamvada, Murthy Vedang
Department of Radiation Oncology, Tata Memorial Hospital and Advanced Centre for Treatment Research and Education in Cancer, Homi Bhabha National Institute, Mumbai, India.
Department of Radiodiagnosis, Tata Memorial Hospital and Advanced Centre for Treatment Research and Education in Cancer, Homi Bhabha National Institute, Mumbai, India.
Int J Radiat Oncol Biol Phys. 2025 Mar 28. doi: 10.1016/j.ijrobp.2025.03.033.
To assess the safety of using combined Gallium68-prostate-specific membrane antigen (PSMA)-positron emission tomography (PET)/computed tomography (CT) (Ga-PSMA-PET/CT) and multiparametric magnetic resonance imaging (mpMRI) for planning dominant intraprostatic lesion (DIL) boost in prostate stereotactic radiation therapy (SBRT) for dose escalation (PROBE).
Patients with intermediate- or high-risk prostate adenocarcinoma with DIL identified on mpMRI and Ga-PSMA-PET/CT and suitable for SBRT were enrolled in this phase 2 trial. Ga-PSMA-PET/CT was fused with mpMRI for gross tumor volume (GTV) delineation. Semiautomatic contouring of DIL was performed using 20% to 90% of the maximum standardized uptake value (SUV) (DILx%). Concordance metrics were used to select the DILx% matching closest to GTV (GTV). Prostate (36.25 Gy), pelvic nodes (25 Gy), GTV: GTV ∪ GTV (40 Gy), and GTV: GTV ∩ GTV (42.5 Gy) were planned for 5-fraction SBRT. All patients received androgen deprivation therapy (ADT) for 6 months. The primary endpoint for the present analysis was concordance (volumetric and spatial) between GTV and GTV. Secondary endpoints included the percentage SUV threshold for GTV contouring (%SUV) and cumulative acute (≤90 days) urinary and gastrointestinal toxicity using Common Terminology Criteria for Adverse Event (CTCAE) v5.0.
Thirty patients (54% intermediate risk, 46% high risk) were enrolled. GTV and GTV showed strong volumetric correlation (Spearman correlation coefficient ρ = 0.817, 95% CI, 0.64-0.91; P < .001). The median Dice similarity coefficient, Jaccard index, and the mean Hausdorff distance for PET and magnetic resonance imaging boost volumes were 0.56, 0.37, and 2.2, respectively. The median %SUV was 48% (IQR, 40%-58%). There was an inverse correlation between DIL SUV and %SUV (Spearman correlation coefficient ρ = -0.598, 95% CI lower -0.79, upper -0.29; P < 0.001). Cumulative grade 2 acute urinary and GI toxicity were 13.3% and 6.6%, respectively, with no grade ≥3 toxicities.
Boost volumes on Ga-PSMA-PET/CT and mpMRI were volumetrically similar, however, with poor spatial concordance. The %SUV threshold for GTV contouring correlated inversely with DIL SUV and was a median of 48%. Based on the favorable acute toxicity profile, PSMA-PET guided intraprostatic boost is likely to be safe for dose escalation in prostate SBRT.
评估在前列腺立体定向放射治疗（SBRT）中使用联合镓68-前列腺特异性膜抗原（PSMA）-正电子发射断层扫描（PET）/计算机断层扫描（CT）（Ga-PSMA-PET/CT）和多参数磁共振成像（mpMRI）来计划前列腺主导性病变（DIL）增敏以进行剂量递增（PROBE）的安全性。
在本2期试验中纳入了经mpMRI和Ga-PSMA-PET/CT识别出有DIL且适合SBRT的中高危前列腺腺癌患者。将Ga-PSMA-PET/CT与mpMRI融合以勾画大体肿瘤体积（GTV）。使用最大标准化摄取值（SUV）的20%至90%进行DIL的半自动轮廓勾画（DILx%）。使用一致性指标来选择最接近GTV（GTV）的DILx%匹配。计划对前列腺（36.25 Gy）、盆腔淋巴结（25 Gy）、GTV：GTV∪GTV（40 Gy）和GTV：GTV∩GTV（42.5 Gy）进行5分割SBRT。所有患者接受6个月的雄激素剥夺治疗（ADT）。本分析的主要终点是GTV和GTV之间的一致性（体积和空间）。次要终点包括用于GTV轮廓勾画的SUV阈值百分比（%SUV）以及使用不良事件通用术语标准（CTCAE）v5.0的累积急性（≤90天）泌尿系统和胃肠道毒性。
纳入了30例患者（54%为中危，46%为高危）。GTV和GTV显示出很强的体积相关性（Spearman相关系数ρ = 0.817，95%CI，0.64 - 0.91；P <.001）。PET和磁共振成像增敏体积的中位Dice相似系数、Jaccard指数和平均豪斯多夫距离分别为0.56、0.37和2.2。中位%SUV为48%（四分位间距，40% - 58%）。DIL SUV与%SUV之间存在负相关（Spearman相关系数ρ = -0.598，95%CI下限 -0.79，上限 -0.29；P < ）。累积2级急性泌尿系统和胃肠道毒性分别为13.3%和6.6%，无≥3级毒性。
Ga-PSMA-PET/CT和mpMRI上的增敏体积在体积上相似，但空间一致性较差。用于GTV轮廓勾画的%SUV阈值与DIL SUV呈负相关且中位数为48%。基于良好的急性毒性特征，PSMA-PET引导的前列腺内增敏在前列腺SBRT剂量递增中可能是安全的。
