Department of Radiation Oncology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India.
Department of Endocrinology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India.
Asian Pac J Cancer Prev. 2023 Nov 1;24(11):3859-3866. doi: 10.31557/APJCP.2023.24.11.3859.
Objective: To determine radiation dose volume threshold in predicting the development of hypothyroidism in cancer patients following neck irradiation. Methods: This is a cross sectional follow up study for patients who had been previously irradiated, prior to enrolment in the study. We have done thyroid dose-volumetric analysis on 120 histologically proven cancer patients in the age group of 18-75 years who received neck irradiation as a part of their definitive or adjuvant radiotherapy with three-dimensional conformal or intensity-modulated radiotherapy technique (3D -CRT or IMRT) and completed at least six months post-radiotherapy. Primary tumor sites included carcinoma or lymphoma of the head and neck, breast, cervical, and upper thoracic esophagus, requiring neck irradiation. Results: The proportion of patients who tested positive for Radiation induced hypothyroidism (RIHT) was found to be 40%, with clinical hypothyroidism and subclinical hypothyroidism being 25.8% and 14.2%, respectively. Time to develop hypothyroidism peaks around two years. Mean thyroid gland dose (Dmean) >28 Gy, thyroid gland volume receiving 40 Gy dose (i.e. V40) >49% and age <50 years were found to be significant risk factors for the development of RIHT on binary logistic regression. RT dose >50 Gy and thyroid gland volume spared from 40 Gy (i.e. VS40) < 2.12cm3 were statistically significant predictors for RIHT on chi-square and (Receiver operating characteristic) ROC curve analysis respectively but not on regression analysis. Conclusion: Dose-volume threshold for the thyroid gland as Dmean <28 Gy and V40 <49% may prevent the development of RIHT.
确定预测癌症患者颈部放疗后发生甲状腺功能减退症的辐射剂量体积阈值。方法：这是一项回顾性随访研究，纳入了此前接受过颈部放疗的患者。我们对 120 名年龄在 18-75 岁之间的组织学证实的癌症患者进行了甲状腺剂量体积分析，这些患者在接受三维适形或调强放疗（3D-CRT 或 IMRT）的根治性或辅助性放疗中接受了颈部放疗，并在放疗后至少 6 个月完成了治疗。原发肿瘤部位包括头颈部、乳房、颈和上胸段食管的癌或淋巴瘤，需要进行颈部放疗。结果：发现放射性甲状腺功能减退症（RIHT）阳性患者的比例为 40%，其中临床甲状腺功能减退症和亚临床甲状腺功能减退症分别为 25.8%和 14.2%。发生甲状腺功能减退症的时间峰值约为两年。二元逻辑回归分析显示，平均甲状腺剂量（Dmean）>28 Gy、甲状腺接受 40 Gy 剂量的体积（即 V40）>49%和年龄<50 岁是发生 RIHT 的显著危险因素。接受 RT 剂量>50 Gy 和甲状腺从 40 Gy 中保留的体积（即 VS40）<2.12cm3 在卡方检验和（Receiver operating characteristic）ROC 曲线分析中是预测 RIHT 的统计学显著指标，但在回归分析中不是。结论：甲状腺的剂量体积阈值为 Dmean<28 Gy 和 V40<49%，可能可以预防 RIHT 的发生。
