Patil Vijay M, Kapoor Rakesh, Chakraborty Santam, Ghoshal Sushmita, Oinam Arun S, Sharma Suresh C
Department of Radiotherapy and Regional Cancer Center, Post Graduate Institute of Medical Education and Research, Chandigarh - 160 012, India.
J Cancer Res Ther. 2010 Oct-Dec;6(4):442-7. doi: 10.4103/0973-1482.77082.
The increasing popularity of intensity-modulated radiotherapy (IMRT) stems from its ability to generate a more conformal plan than hitherto possible with conventional planning. As a result, IMRT is in widespread use across diverse indications. However, the inherent nature of IMRT delivery makes it monitor unit inefficient and leads to increased normal tissue integral dose. This in turn may result in an increased risk of radiation-induced second malignancies.
To calculate the risk of second malignancy post-IMRT.
Observational study in a tertiary care institute.
Eighteen previously untreated patients with head and neck cancers (n = 10) and prostate cancer (n = 8) were selected. In these patients, selected infield organs around the planning target volume were contoured, viz. brain and thyroid in patients with head and neck cancer and bladder, rectum and small intestine in patients with carcinoma prostate. The estimates of radiation-induced malignancies in these organs and the whole of the body were derived using the concept of Organ Equivalent Dose.
Descriptive statistics (SPSS version 12).
The modal estimated incidence of radiation-induced malignancies was 129.87, 1.4, 0.10, 3.42, 7.789 and 129.85 per 10,000 person-years for the brain, thyroid, bladder, rectum, small intestine and whole body respectively.
The estimated risk of radiation-induced malignancies in the thyroid and rectum was similar to the available literature, while the risk for bladder carcinomas was lower than that reported. However, the calculated risk of radiation-induced tumors of the brain was more than that reported with conventional radiation therapy. We propose that estimation of the risk of radiation-induced malignancies should be a part of the plan evaluation process and special care should be taken before using this modality in young patients with benign tumors in the head and neck region.
调强放射治疗（IMRT）越来越受欢迎，这源于它能够生成比传统放疗计划更适形的方案。因此，IMRT在各种适应症中得到广泛应用。然而，IMRT的固有特性使其监测单位效率低下，并导致正常组织积分剂量增加。这反过来可能会增加辐射诱发第二原发恶性肿瘤的风险。
计算IMRT后发生第二原发恶性肿瘤的风险。
在一家三级医疗机构进行的观察性研究。
选取18例未经治疗的头颈部癌患者（n = 10）和前列腺癌患者（n = 8）。在这些患者中，对计划靶区周围选定的靶区内器官进行轮廓勾画，即头颈部癌患者的脑和甲状腺，以及前列腺癌患者的膀胱、直肠和小肠。利用器官等效剂量的概念得出这些器官及全身辐射诱发恶性肿瘤的估计值。
描述性统计（SPSS 12版）。
脑、甲状腺、膀胱、直肠、小肠和全身辐射诱发恶性肿瘤的估计发病率模态分别为每10000人年129.87、1.4、0.10、3.42、7.789和129.85。
甲状腺和直肠辐射诱发恶性肿瘤的估计风险与现有文献相似，而膀胱癌的风险低于报道值。然而，计算得出的脑辐射诱发肿瘤的风险高于传统放疗的报道值。我们建议，辐射诱发恶性肿瘤风险的估计应成为计划评估过程的一部分，在对头颈部区域患有良性肿瘤的年轻患者使用这种治疗方式之前应格外小心。
