(1) Background: Radiotherapy (RT) is a central component for the treatment of many head and neck cancers. In this systematic review of the literature, we aimed to characterize and quantify the published evidence on RT-related hypothyroidism, including estimated incidence, clinical risk factors, and dosimetric parameters that may be used to guide clinical decision making. Furthermore, we aimed to identify potential areas of improvement in the prevention and clinical management of RT-induced hypothyroidism, including the role of modern advanced therapeutic techniques. (2) Methods: We conducted a systemic review of the literature in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. PubMed and Google Scholar were searched to identify original research articles describing the incidence, mechanism, dosimetry, treatment, or prevention of radiation-related hypothyroidism for adults receiving RT for the treatment of head and neck cancers. The snowball method was used to identify additional articles. For identified articles, we tabulated several datapoints, including publication date, patient sample size, estimated hypothyroidism incidence, cancer site/type, follow-up period, radiation modality and technique, use of multimodality therapy, method of thyroid function evaluation, and proposed dosimetric predictors of hypothyroidism. (3) Results: One hundred and eleven articles met inclusion criteria, reflecting a range of head and neck cancer subtypes. There was a large variation in the estimated incidence of RT-related hypothyroidism, with a median estimate of 36% (range 3% to 79%). Reported incidence increased in later publication dates, which was likely related to improved screening and longer follow up. There were a wide variety of predictive metrics used to identify patients at high risk of hypothyroidism, the most common of which were volumetric and mean dosimetrics related to the thyroid gland (Vxx%, Dmean). More recently, there has been increasing evidence to suggest that the thyroid gland volume itself and the volume of the thyroid gland spared from high-dose radiation (VSxx) may better predict thyroid function after RT. There were no identified studies investigating the role of advanced radiotherapeutic techniques such as MRI-guided RT or particle therapy to decrease RT-related hypothyroidism. Conclusions: Hypothyroidism is a common toxicity resulting from therapeutic radiation for head and neck cancer with recent estimates suggesting 40–50% of patients may experience hypothyroidism after treatment. Dosimetric predictive models are increasingly able to accurately identify patients at risk of hypothyroidism, especially those utilizing thyroid VS metrics. Further investigation regarding the potential for advanced radiotherapeutic therapies to decrease RT-induced thyroid dysfunction is needed.
（1）背景：放射治疗（RT）是多种头颈部癌症治疗的核心组成部分。在本系统性文献综述中，我们旨在描述和量化已发表的关于放疗相关甲状腺功能减退症的证据，包括估计发病率、临床危险因素以及可用于指导临床决策的剂量学参数。此外，我们旨在明确放疗所致甲状腺功能减退症在预防和临床管理方面的潜在改进领域，包括现代先进治疗技术的作用。（2）方法：我们依据系统综述和荟萃分析优先报告条目（PRISMA）指南进行了系统性文献综述。通过检索PubMed和Google Scholar，识别出描述接受头颈部癌症放疗的成人患者中放疗相关甲状腺功能减退症的发病率、机制、剂量学、治疗或预防的原创研究文章。采用滚雪球法识别补充文献。对于识别出的文章，我们列表汇总了多个数据点，包括发表日期、患者样本量、估计的甲状腺功能减退症发病率、癌症部位/类型、随访期、放疗方式和技术、多模式治疗的应用、甲状腺功能评估方法以及提出的甲状腺功能减退症剂量学预测因子。（3）结果：共111篇文章符合纳入标准，涵盖了多种头颈部癌症亚型。放疗相关甲状腺功能减退症的估计发病率差异很大，中位估计值为36%（范围3%至79%）。后期发表的文章中报告的发病率有所上升，这可能与筛查手段改进和随访时间延长有关。用于识别甲状腺功能减退症高风险患者的预测指标多种多样，最常见的是与甲状腺相关的体积和平均剂量学指标（Vxx%、Dmean）。最近，越来越多的证据表明，甲状腺体积本身以及避开高剂量照射的甲状腺体积（VSxx）可能更好地预测放疗后的甲状腺功能。目前尚未发现研究探讨先进放疗技术（如MRI引导放疗或粒子治疗）在降低放疗相关甲状腺功能减退症方面的作用。结论：甲状腺功能减退症是头颈部癌症治疗性放疗的常见毒性反应，近期估计表明40-50%的患者可能在治疗后出现甲状腺功能减退。剂量学预测模型越来越能够准确识别存在甲状腺功能减退风险的患者，尤其是那些利用甲状腺VS指标的方法。需要进一步研究先进放疗技术在降低放疗所致甲状腺功能障碍方面的潜力。
肿瘤(癌症)患者之家