AUTHOR=Jiang Yongji , Liu Simin , Qiu Xiaotong , Huo Yanlei , Zhang Xiaoying , Cai Haidong , Lv Zhongwei , Ma Chao 

TITLE=Do radioiodine-avid lymph nodes from differentiated thyroid cancer on the initial posttherapy scan need repeated 131I therapy?

JOURNAL=Frontiers in Endocrinology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2023.1099449

DOI=10.3389/fendo.2023.1099449

ISSN=1664-2392

ABSTRACT=<sec><title>Background</title><p>Residual/recurrent lymph node metastase (LNM) is often found after differentiated thyroid cancer (DTC) surgery. This study aimed to investigate whether patients complicated with radioiodine-avid (<sup>131</sup>I+) lymph nodes from DTC on the initial posttherapy scan (PTS) need repeated <sup>131</sup>I therapy.</p></sec><sec><title>Methods</title><p>From June 2013 to August 2022, DTC patients with <sup>131</sup>I+ lymph nodes on the initial PTS who received at least two cycles of <sup>131</sup>I therapy were retrospectively enrolled. They were divided into a complete response (CR) group and an incomplete response (IR) group according to their response to the initial <sup>131</sup>I therapy based on the 2015 American Thyroid Association (ATA) guidelines.</p></sec><sec><title>Results</title><p>A total of 170 DTC patients with <sup>131</sup>I+ lymph nodes on the initial PTS were included; 42/170 (24.7%) patients were classified into the CR group and 128/170 (75.9%) were classified into the IR group according to their response to the initial <sup>131</sup>I therapy. None of the 42 CR patients had disease progression at the subsequent follow-up, and 37/170 (21.8%) IR patients improved after repeated therapy. Univariate analysis showed that N stage (<italic>P=</italic>0.002), stimulated thyroglobulin (sTg) level before initial <sup>131</sup>I therapy (<italic>P</italic>&lt;0.001), LNM size (<italic>P</italic>&lt;0.001), number of total residual/recurrent LNM (<italic>P=</italic>0.021), radioiodine-nonavid (<sup>131</sup>I-) LNM (<italic>P=</italic>0.002) and ultrasound features (<italic>P</italic>&lt;0.001) were related to the initial treatment response. On multivariate analysis, sTg level (<italic>OR</italic>=1.186, <italic>P</italic>&lt;0.001) and LNM size (<italic>OR</italic>=1.533, <italic>P</italic>=0.004) were independent risk factors for IR after initial <sup>131</sup>I therapy. The optimal sTg level and LNM size cutoff value for predicting the treatment response after initial <sup>131</sup>I therapy were 18.2 µg/l and 5mm.</p></sec><sec><title>Conclusion</title><p>This study suggested that approximately one-quarter of patients with <sup>131</sup>I+ lymph nodes on initial PTS, especially those with N0 or N1a stage, lower sTg level, smaller LNM size, ≤2 residual/recurrent LNMs, negative ultrasound features and no <sup>131</sup>I- LNM, remain stable after one cycle of <sup>131</sup>I therapy and do not need repeated therapy.</p></sec>