1 University of Michigan Medical School, University of Michigan Health System , Ann Arbor, Michigan.
2 Department of Nuclear Medicine, University of Michigan Health System , Ann Arbor, Michigan.
Thyroid. 2018 May;28(5):593-600. doi: 10.1089/thy.2017.0434. Epub 2018 Apr 23.
After initial surgical treatment of differentiated thyroid cancer (DTC) residual lymph node metastases are often found at the time of radioactive iodine (I) therapy. Recurrence of DTC is due to persistent disease not removed at initial surgery which also did not respond to I treatment. This study aimed at determining locations of, and reasons for, residual nodal metastases detected by I scans with single-photon emission computed tomography (SPECT/CT) obtained prior to radioiodine therapy following surgical treatment of DTC.
This is a retrospective study of 352 patients with intermediate and high-risk DTC treated with I therapy at the University of Michigan from 2007 to 2014. All patients underwent total thyroidectomy with or without lymph node dissection followed by radioiodine therapy. Pre-ablation diagnostic I scans with SPECT/CT were used postoperatively to localize nodal metastases, which were then compared with the cervical lymph node basins dissected at the time of surgery to determine the reason for residual nodal metastases: incomplete nodal dissection versus preoperative unrecognized nodal metastases.
Of the 352 patients in the study, 146 (41.5%) had residual nodal metastases detected on I scans with SPECT/CT following initial surgery but prior to I therapy. Among the 146 patients with residual disease, there were a total of 218 distinct nodal metastases. Relative to the primary tumor, 71.6% (n = 156) of metastases were ipsilateral, 22.0% (n = 48) were contralateral, and 6.4% (n = 14) were non-sided in the central neck (level VI/VII). Cervical lymph node levels VI, III, and II had the greatest frequencies of residual metastases (33.9%, 22.9%, 18.8%, respectively). Residual metastases occurred because of incomplete nodal dissection (49.3%), lack of preoperative identification (37.7%), or a combination of both (13%).
Residual nodal metastasis following initial surgical treatment for regionally advanced differentiated thyroid cancer is rather common on highly sensitive I scans with SPECT/CT and is due to both unrecognized nodal involvement preoperatively and incomplete removal of metastatic lymph nodes during compartment-orientated nodal dissection. The surgical management of high-risk DTC should include preoperative imaging to evaluate for nodal metastases in the central and lateral neck and compartment-orientated nodal dissection of involved compartments. Attention should be given to complete dissection in levels VI, III, and II, particularly when dissecting compartments ipsilateral to the primary tumor.
分化型甲状腺癌（DTC）初次手术治疗后，放射性碘（I）治疗时常发现残留淋巴结转移。DTC 的复发是由于初次手术时未切除的持续性疾病，且对 I 治疗无反应。本研究旨在确定 DTC 患者在接受 I 治疗前进行的单光子发射计算机断层扫描（SPECT/CT）碘扫描检测到的残留淋巴结转移的位置和原因。
这是一项回顾性研究，纳入了 2007 年至 2014 年期间在密歇根大学接受 I 治疗的 352 例中高危 DTC 患者。所有患者均行甲状腺全切除术加或不加淋巴结清扫术，随后行 I 治疗。术后行消融前诊断性 I 扫描 SPECT/CT，以定位淋巴结转移，然后与手术时切除的颈部淋巴结区进行比较，以确定残留淋巴结转移的原因：淋巴结清扫不彻底还是术前未识别的淋巴结转移。
在这项研究的 352 例患者中，有 146 例（41.5%）在初次手术后但在 I 治疗前的 SPECT/CT 碘扫描中发现有残留淋巴结转移。在 146 例有残留疾病的患者中，共有 218 个不同的淋巴结转移灶。与原发灶相比，71.6%（n=156）的转移灶位于同侧，22.0%（n=48）位于对侧，6.4%（n=14）位于中央颈部（VI/VII 水平）。颈部淋巴结 VI、III 和 II 水平发生残留转移灶的频率最高（分别为 33.9%、22.9%和 18.8%）。残留转移灶的发生原因是淋巴结清扫不彻底（49.3%）、术前未识别（37.7%）或两者兼有（13%）。
对于局部晚期分化型甲状腺癌，初次手术治疗后，通过高度敏感的 SPECT/CT 碘扫描检测到残留淋巴结转移相当常见，原因是术前未识别的淋巴结受累和分区性淋巴结清扫术时转移性淋巴结切除不彻底。高危 DTC 的手术治疗应包括术前影像学检查，以评估中央和侧颈部的淋巴结转移，并对受累的分区进行分区性淋巴结清扫。应特别注意对原发灶同侧的 VI、III 和 II 水平进行彻底清扫。
