Background

ESTIMABL2, a multicentre randomised phase 3 trial in patients with low-risk differentiated thyroid cancer (ie, pT1am or pT1b, N0 [no evidence of regional nodal involvement] or Nx [involvement of regional lymph nodes that cannot be assessed in the absence of neck dissection]), showed the non-inferiority of a follow-up strategy without radioactive iodine (¹³¹I) administration compared with a postoperative ¹³¹I administration at 3 years post-randomisation. Here, we report a pre-specified analysis after 5 years of follow-up.

Methods

Patients treated with total thyroidectomy with or without prophylactic neck lymph node dissection, without postoperative suspicious findings on neck ultrasonography, were randomly assigned to the no-radioiodine group or to the radioiodine group (1·1 GBq-30 mCi after recombinant human thyrotropin-stimulating hormone). Follow-up consisted of annual thyroglobulin and thyroglobulin antibody determinations during levothyroxine treatment and neck ultrasonography in odd-numbered years. An event was defined as abnormal foci of ¹³¹I uptake on the post-treatment whole-body-scan requiring subsequent treatment, abnormal neck ultrasonography, elevated thyroglobulin levels, increasing titres or appearance of thyroglobulin antibody (using the same laboratory assay), or a combination of these definitions. Non-inferiority of the proportion of patients without an event in one group compared with the other at 5 years after randomisation was shown if this proportion and its CI did not differ by more than –5%. This study was registered on ClinicalTrials.gov (NCT01837745) and is completed.

Findings

Of the 776 patients (n=642 [82·7%] female and n=134 [17·3%] male, median age 52·9 years [IQR 42·6–63·1]) enrolled, 698 were evaluable at 5 years. The proportions of patients without events were 93·2% in the no-radioiodine group and 94·8% in the radioiodine group, for a difference of –1·6% (90% CI –4·5 to 1·4). Events consisted of structural or functional abnormalities (n=11) and biological abnormalities (n=31).

Interpretation

The non-inferiority of a follow-up strategy compared with postoperative ¹³¹I administration in low risk differentiated thyroid cancer was confirmed at 5 years. There is no loss of opportunity in following these patients without postoperative ablation.

Funding

Programme de Recherche Hospitalier Clinique.

中文翻译：

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低危甲状腺癌患者无放射性碘甲状腺切除术：前瞻性随机ESTIMABL2试验的 5 年随访

 背景

ESTIMABL2，一项针对低风险分化型甲状腺癌 （即 pT1am 或 pT1b，N0 [无区域淋巴结受累的证据] 或 Nx [在没有颈部夹层的情况下无法评估的区域淋巴结受累] 患者的多中心随机 3 期试验显示，与术后 ¹³¹ 相比，无放射性碘 （¹³¹I） 给药的随访策略不劣效I 在随机分组后 3 年给药。在这里，我们报告了 5 年随访后的预先指定的分析。

 方法

接受全甲状腺切除术联合或不联合预防性颈部淋巴结清扫术，术后颈部超声无可疑发现的患者，随机分配到无放射性碘组或放射性碘组 （重组人促甲状腺激素后 1·1 GBq-30 mCi）。随访包括左旋甲状腺素治疗期间的年度甲状腺球蛋白和甲状腺球蛋白抗体测定以及奇数年的颈部超声检查。事件被定义为治疗后全身扫描中 ¹³¹I 摄取的异常病灶需要后续治疗、颈部超声检查异常、甲状腺球蛋白水平升高、甲状腺球蛋白抗体滴度增加或外观（使用相同的实验室检测），或这些定义的组合。如果该比例及其 CI 差异不超过 –5%，则显示随机分组后 5 年一组无事件的患者比例与另一组患者比例的非劣效性。这项研究于 ClinicalTrials.gov （NCT01837745） 注册并已完成。

 发现

在入组的 776 名患者 （n=642 [82·7%] 女性和 n=134 [17·3%] 男性，中位年龄 52·9 岁 [IQR 42·6–63·1]）中，有 698 名在 5 年时可评估。无放射性碘组无事件的患者比例为 93·2%，放射性碘组为 94·8%，差异为 -1·6%（90% CI -4·5 至 1·4）。事件包括结构或功能异常 （n=11） 和生物异常 （n=31）。

 解释

在 5 年时证实了低风险分化型甲状腺癌与术后 ¹³¹I 给药相比，随访策略的非劣效性。在没有术后消融的情况下跟踪这些患者不会失去机会。

 资金

Program de Recherche Hospitalier Clinique.