Department of Radiation Oncology, Clinical Oncology School of Fujian Medical University, Fujian Cancer Hospital, Fuzhou, China.
Department of Epidemiology and Health Statistics, Fujian Provincial Key Laboratory of Environment Factors and Cancer, School of Public Health, Fujian Medical University, Fuzhou, China.
Radiat Oncol. 2023 Aug 25;18(1):141. doi: 10.1186/s13014-023-02329-x.
Hypothyroidism (HT) and subclinical HT after radiotherapy is frequent in nasopharyngeal carcinoma (NPC) patients, results in negative impact on patients' quality of life. The percentage of thyroid volume receiving more than 40 Gy (V40) ≤ 85% was reported to be a useful dose constraint to adopt during intensity-modulated radiation therapy (IMRT) planning. This study aims to verify whether V40 ≤ 85% can be used as an effective dose constraint in IMRT planning in a randomized clinical trial.
This single-center 1:1 randomized clinical trial was conducted in Fujian province hospital between March 2018 and September 2022. All patients were treated with IMRT and randomized to induction chemo followed by concurrent chemo-IMRT or concurrent chemo-IMRT alone. Ninety-two clinically NPC patients were included in this study. The thyroid function tests were performed for all patients before and after radiation at regular intervals. Thyroid dose-constraint was defined as V40 ≤ 85%. The primary outcome in this study was subclinical HT.
Median follow up was 34 months. Significant difference in the incidence of subclinical HT between the thyroid dose-constraint group and unrestricted group was observed (P = 0.023). The risk of subclinical HT in the thyroid dose-constraint group was lower than that in the unrestricted group (P = 0.022). Univariate and multivariate cox regression analysis indicated that thyroid dose-constraint was a protective effect of subclinical HT (HR = 0.408, 95% CI 0.184-0.904; HR = 0.361, 95% CI 0.155-0.841).
V40 ≤ 85% can be used as an effective dose constraint in IMRT planning to prevent radiation-induced subclinical HT.
甲状腺功能减退症（HT）和放射性治疗后的亚临床 HT 在鼻咽癌（NPC）患者中很常见，对患者的生活质量产生负面影响。据报道，甲状腺接受超过 40Gy（V40）的百分比≤85％是在调强放疗（IMRT）计划中采用的有用剂量限制。本研究旨在验证在随机临床试验中，V40≤85％是否可作为 IMRT 计划中的有效剂量限制。
这是一项单中心 1：1 随机临床试验，于 2018 年 3 月至 2022 年 9 月在福建省医院进行。所有患者均接受 IMRT 治疗，并随机分为诱导化疗后同步化疗-IMRT 或同步化疗-IMRT 单独治疗。本研究纳入了 92 例临床 NPC 患者。所有患者在放疗前后定期进行甲状腺功能检查。甲状腺剂量限制定义为 V40≤85％。本研究的主要结局是亚临床 HT。
中位随访时间为 34 个月。在甲状腺剂量限制组和无限制组之间，亚临床 HT 的发生率存在显著差异（P=0.023）。甲状腺剂量限制组的亚临床 HT 风险低于无限制组（P=0.022）。单因素和多因素 Cox 回归分析表明，甲状腺剂量限制是亚临床 HT 的保护作用（HR=0.408，95％CI 0.184-0.904；HR=0.361，95％CI 0.155-0.841）。
V40≤85％可作为 IMRT 计划中的有效剂量限制，以预防放射性诱导的亚临床 HT。
