Department of Radiology, The Jikei University School of Medicine, 3-25-8, Nishi-shinbashi, Minato-ku, Tokyo, 105-8461, Japan.
Ann Nucl Med. 2020 Dec;34(12):920-925. doi: 10.1007/s12149-020-01523-1. Epub 2020 Sep 17.
In patients with differentiated thyroid carcinoma (DTC) with a microscopically positive tumor margin, the optimal first dose of I-131 during adjuvant radioactive iodine (RAI) therapy to improve relapse-free survival (RFS) is unclear. Due to the limited number of hospital beds, 1110 MBq of I-131 is administered to such patients in Japan. This study primarily aimed to retrospectively determine the difference in RFS between high-dose (3700 MBq) and low-dose (1110 MBq) adjuvant RAI therapies in DTC patients with a microscopically positive tumor margin. The secondary aim was to investigate the background factors affecting RFS.
Forty-eight consecutive patients (15 men and 33 women) who underwent total thyroidectomy between April 2007 and December 2017 for DTC without gross residual tumors and distant metastasis, and who were diagnosed with a positive margin histopathologically, followed by RAI therapy, were enrolled. We retrospectively investigated initial I-131 dose, classifying it into high-dose and low-dose groups. The primary endpoint was RFS. Relapse was considered in the following cases: patients with visible recurrent tumor and/or metastasis on neck ultrasound and/or computed tomography, and patients without visible tumor, but with clearly increasing thyroglobulin levels on follow-up every 3-6 months. RFS outcomes were analyzed using the Kaplan-Meier method. Univariate analysis was performed using the log-rank test, and multivariate analysis was undertaken using the Cox proportional hazard model.
There were nine cases of recurrence (52.9%) in the low-dose group and seven in the high-dose group (22.5%) during follow-up. The estimated median RFS was 69.4 months in the low-dose group and 120.7 months in the high-dose group. High-dose administration was associated with improved RFS, as demonstrated by Kaplan-Meier survival curves (log-rank test [P = 0.009]). Patient factors associated with worse RFS included low-dose administration (hazard ratio [HR] = 91.9; 95% confidence interval [CI] = 7.66-1102.79); P < 0.001), T4 stage (HR = 1.88; 95% CI = 0.44-8.10; P = 0.015), and presence of central lymph node metastases (HR = 190; 95% CI = 3.80-9496; P = 0.009). The most common type of recurrence was lymph node metastasis.
Patients with microscopically positive tumor margins could benefit from RAI with high activities.
对于显微镜下甲状腺癌（DTC）肿瘤边缘阳性的患者，辅助放射性碘（RAI）治疗中首次使用 I-131 的最佳剂量以改善无复发生存率（RFS）尚不清楚。由于医院床位有限，日本仅对这些患者给予 1110MBq 的 I-131。本研究主要旨在回顾性确定高剂量（3700MBq）和低剂量（1110MBq）辅助 RAI 治疗对显微镜下肿瘤边缘阳性的 DTC 患者的 RFS 差异。次要目的是研究影响 RFS 的背景因素。
纳入 2007 年 4 月至 2017 年 12 月期间因 DTC 行甲状腺全切除术（无肉眼残留肿瘤和远处转移）且组织病理学诊断为阳性边缘的 48 例连续患者（男性 15 例，女性 33 例），行 RAI 治疗。我们回顾性地调查了初始 I-131 剂量，分为高剂量和低剂量组。主要终点是 RFS。复发被认为是以下情况：颈部超声和/或计算机断层扫描可见复发性肿瘤和/或转移的患者，以及没有可见肿瘤但随访中甲状腺球蛋白水平明显升高的患者。使用 Kaplan-Meier 法分析 RFS 结果。使用对数秩检验进行单因素分析，使用 Cox 比例风险模型进行多因素分析。
在随访期间，低剂量组有 9 例（52.9%）复发，高剂量组有 7 例（22.5%）。低剂量组的中位 RFS 估计为 69.4 个月，高剂量组为 120.7 个月。Kaplan-Meier 生存曲线显示高剂量给药与改善的 RFS 相关（对数秩检验[P=0.009]）。与 RFS 较差相关的患者因素包括低剂量给药（风险比[HR]=91.9；95%置信区间[CI]=7.66-1102.79）；P<0.001）、T4 期（HR=1.88；95%CI=0.44-8.10；P=0.015）和中央淋巴结转移（HR=190；95%CI=3.80-9496；P=0.009）。最常见的复发类型是淋巴结转移。
显微镜下肿瘤边缘阳性的患者可能受益于高活性的 RAI。
