Staal Floor H E, Janssen Jorinde, Oprea-Lager Daniela E, Engelen Antoine M, van Limbergen Evert J, Smeenk Robert Jan, de Jong Marianne A A, Budiharto Tom C G, Jacobs Inge, Haverkort Dorien M A D, Brouwer Charlotte L, Ng Wei Siang Kelvin, Langendijk Johannes A, Verzijlbergen J Fred, de Jong Ingle Jan, Noordzij Walter, Aluwini Shafak
Department of Radiation Oncology, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands.
Department of Radiation Oncology, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands.
Int J Radiat Oncol Biol Phys. 2024 Mar 1;118(3):688-696. doi: 10.1016/j.ijrobp.2023.09.016. Epub 2023 Sep 18.
Prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) scan is the standard imaging procedure for biochemical recurrent prostate cancer postprostatectomy because of its high detection rate at low serum prostate-specific antigen levels. However, existing guidelines for clinical target volume (CTV) in prostate bed salvage external beam radiation therapy (sEBRT) are primarily based on experience-based clinical consensus and have been validated using conventional imaging modalities. Therefore, this study aimed to optimize CTV definition in sEBRT by using PSMA PET/CT-detected local recurrences (LRs).
Patients with suspected LR on PSMA PET/CT postprostatectomy were retrospectively enrolled in 9 Dutch centers. Anonymized scans were centrally reviewed by an expert nuclear medicine physician. Each boundary of the CTV guideline from the Groupe Francophone de Radiothérapie en Urologie (GFRU) was evaluated and adapted to improve the accuracy and coverage of the area at risk of LR (CTV) on PSMA PET/CT. The proposed CTV adaptation was discussed with the radiation oncologists of the participating centers, and final consensus was reached. To assess reproducibility, the participating centers were asked to delineate 3 new cases according to the new PERYTON-CTV, and the submitted contours were evaluated using the Dice similarity coefficient (DSC).
After central review, 93 LRs were identified on 83 PSMA PET/CTs. The proposed CTV definition improved the coverage of PSMA PET/CT-detected LRs from 67% to 96% compared with the GFRU-CTV, while reducing the GFRU-CTV by 25%. The new CTV was highly reproducible, with a mean DSC of 0.82 (range, 0.81-0.83).
This study contributes to the optimization of CTV definition in postprostatectomy sEBRT by using the pattern of LR detected on PSMA PET/CT. The PERYTON-CTV is highly reproducible across the participating centers and ensures coverage of 96% LRs while reducing the GFRU-CTV by 25%.
前列腺特异性膜抗原正电子发射断层扫描/计算机断层扫描（PSMA PET/CT）因其在低血清前列腺特异性抗原水平下具有较高的检测率，已成为前列腺切除术后生化复发前列腺癌的标准成像检查。然而，前列腺床挽救性外照射放疗（sEBRT）中临床靶区（CTV）的现有指南主要基于经验性临床共识，且是使用传统成像方式验证的。因此，本研究旨在通过利用PSMA PET/CT检测到的局部复发（LR）来优化sEBRT中的CTV定义。
荷兰9个中心对前列腺切除术后PSMA PET/CT上疑似LR的患者进行回顾性纳入。匿名扫描图像由一名核医学专家医师进行集中审查。对法语国家泌尿外科放射治疗小组（GFRU）的CTV指南的每个边界进行评估和调整，以提高PSMA PET/CT上LR风险区域（CTV）的准确性和覆盖范围。与参与中心的放射肿瘤学家讨论了提议的CTV调整方案，并达成最终共识。为评估可重复性，要求参与中心根据新的佩里顿CTV（PERYTON-CTV）勾勒3个新病例，使用骰子相似系数（DSC）对提交的轮廓进行评估。
经集中审查，在83例PSMA PET/CT上识别出93处LR。与GFRU-CTV相比，提议的CTV定义将PSMA PET/CT检测到的LR的覆盖范围从67%提高到96%，同时使GFRU-CTV减少了25%。新的CTV具有高度可重复性，平均DSC为0.82（范围为0.81 - 0.83）。
本研究通过利用PSMA PET/CT检测到的LR模式，为前列腺切除术后sEBRT中CTV定义的优化做出了贡献。佩里顿CTV在各参与中心具有高度可重复性，确保了96%的LR得到覆盖，同时使GFRU-CTV减少了25%。
