Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark.
Department of Oncology, Aarhus University Hospital, Aarhus, Denmark.
Acta Oncol. 2023 Oct;62(10):1222-1229. doi: 10.1080/0284186X.2023.2254925. Epub 2023 Sep 8.
Patients with stage II seminoma have traditionally been treated with photons to the retroperitoneal and iliac space, which leads to a substantial dose bath to abdominal and pelvic organs at risk (OAR). As these patients are young and with excellent prognosis, reducing dose to OAR and thereby the risk of secondary cancer is of utmost importance. We compared IMPT to opposing IMRT fields and VMAT, assessing dose to OAR and both overall and organ-specific secondary cancer risk.
A comparative treatment planning study was conducted on planning CT-scans from ten patients with stage II seminoma, treated with photons to a 'dog-leg' field with doses ranging from 20 to 25 Gy and a 10 Gy sequential boost to the metastatic lymph node(s). Photon plans were either 3-4 field IMRT (Eclipse) or 1-2 arc VMAT (Pinnacle). Proton plans used robust (5 mm; 3.5%) IMPT (Eclipse), multi field optimization with 3 posterior fields supplemented by 2 anterior fields at the level of the iliac vessels. Thirty plans were generated. Mean doses to OARs were compared for IMRT vs IMPT and VMAT vs IMPT. The risk of secondary cancer was calculated according to the model described by Schneider, using excess absolute risk (EAR, per 10,000 persons per year) for body outline, stomach, duodenum, pancreas, bowel, bladder and spinal cord.
Mean doses to all OARs were significantly lower with IMPT except similar kidney (IMRT) and spinal cord (VMAT) doses. The relative EAR for body outline was 0.59 for IMPT/IMRT ( < .05) and 0.33 for IMPT/VMAT ( < .05). Organ specific secondary cancer risk was also lower for IMPT except for pancreas and duodenum.
Proton therapy reduced radiation dose to OAR compared to both IMRT and VMAT plans, and potentially reduce the risk of secondary cancer both overall and for most OAR.
传统上，II 期精原细胞瘤患者采用光子照射腹膜后和髂骨间隙，这会导致腹部和盆腔危险器官（OAR）受到大量剂量照射。由于这些患者年轻且预后良好，降低 OAR 剂量，从而降低继发癌症的风险至关重要。我们比较了 IMPT 与对向 IMRT 野和 VMAT，评估了 OAR 剂量以及整体和器官特异性继发癌症风险。
对 10 例 II 期精原细胞瘤患者的计划 CT 扫描进行了对比治疗计划研究，这些患者采用光子照射“狗腿”野，剂量范围为 20 至 25Gy，然后对转移性淋巴结（s）进行 10Gy 序贯加量。光子计划为 3-4 野 IMRT（Eclipse）或 1-2 弧 VMAT（Pinnacle）。质子计划采用 Robust（5mm；3.5%）IMPT（Eclipse），多野优化，3 个后野辅以髂血管水平的 2 个前野。生成了 30 个计划。比较了 IMRT 与 IMPT 和 VMAT 与 IMPT 之间的 OAR 平均剂量。根据 Schneider 模型计算继发癌症风险，使用身体轮廓、胃、十二指肠、胰腺、肠道、膀胱和脊髓的超额绝对风险（EAR，每年每 10000 人）。
除了相似的肾脏（IMRT）和脊髓（VMAT）剂量外，IMPT 对所有 OAR 的平均剂量均显著降低。对于 IMPT/IMRT（<0.05）和 IMPT/VMAT（<0.05），身体轮廓的相对 EAR 分别为 0.59 和 0.33。除了胰腺和十二指肠外，IMPT 对器官特异性继发癌症风险也较低。
与 IMRT 和 VMAT 计划相比，质子治疗降低了 OAR 的辐射剂量，并可能降低整体和大多数 OAR 的继发癌症风险。
