Department of Medical Physics, Faculty of Medicine, University of Crete, P.O. Box 2208, 71003, Iraklion, Crete, Greece.
Department of Radiotherapy and Oncology, University Hospital of Iraklion, 71110, Iraklion, Crete, Greece.
Phys Eng Sci Med. 2021 Jun;44(2):573-579. doi: 10.1007/s13246-021-01002-5. Epub 2021 Apr 28.
This study was conducted to estimate the lifetime radiation-induced bone and soft tissue sarcoma risks from intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) for uterine cervix carcinoma. 13 cervical cancer patients were included. The bone and soft tissue structures were defined on patients' treatment planning computed tomography (CT) scans. Both CT-based IMRT and VMAT plans with 6 MV photons delivering 45 Gy to the target site were designed for each patient. The organ equivalent dose (OED) and the lifetime attributable risk (LAR) for developing bone or soft tissue sarcoma were estimated using treatment planning data and a non-linear mechanistic model. The estimation method did not consider the survival rates following radiotherapy and the use of brachytherapy treatments. The patient-specific OEDs of the bone structure from IMRT and VMAT were 2.33-2.83 and 2.34-2.82 Gy, respectively. The corresponding values for the soft tissue structure were 1.27-1.70 and 1.32-1.73 Gy. An insignificant difference was found between the patient-specific OEDs and the directly proportional sarcoma risks (bone: P = 0.07; soft tissue: P = 0.38). The LAR for the development of a bone sarcoma varied from 0.05 to 0.16% by the patient's age during irradiation and the applied treatment delivery technique. The corresponding LAR range for radiation-induced soft-tissue sarcoma was 0.08-0.27%. The above LARs resulted in a relative risk of more than 1.20 indicating that IMRT or VMAT may lead to a considerable risk increase of developing bone or soft tissue sarcoma exceeding 20% in respect to the current incidence of these malignancies in unexposed population.
本研究旨在估算子宫颈癌调强放疗（IMRT）和容积旋转调强放疗（VMAT）的终生放射性骨和软组织肉瘤风险。纳入 13 例宫颈癌患者。在患者的治疗计划计算机断层扫描（CT）扫描上定义了骨和软组织结构。为每位患者设计了基于 CT 的 IMRT 和 6 MV 光子的 VMAT 计划，将 45 Gy 传递至靶区。使用治疗计划数据和非线性机制模型估算发生骨或软组织肉瘤的器官等效剂量（OED）和终生归因风险（LAR）。该估算方法未考虑放疗后的生存率和近距离放疗的应用。来自 IMRT 和 VMAT 的骨结构的患者特异性 OED 分别为 2.33-2.83 和 2.34-2.82 Gy。软组织结构的相应值分别为 1.27-1.70 和 1.32-1.73 Gy。患者特异性 OED 与直接成正比的肉瘤风险之间无显著差异（骨：P=0.07；软组织：P=0.38）。发生骨肉瘤的 LAR 因照射时患者年龄和应用的治疗递送技术而异，范围为 0.05-0.16%。发生放射性软组织肉瘤的相应 LAR 范围为 0.08-0.27%。上述 LAR 导致相对风险超过 1.20，表明与未暴露人群中这些恶性肿瘤的当前发病率相比，IMRT 或 VMAT 可能导致骨或软组织肉瘤的风险显著增加超过 20%。
