目的：本研究旨在分析碘难治性分化型甲状腺癌（radioiodine refractory differentiated thyroid cancer, RAIR-DTC）患者的预后及影响因素。

方法：回顾性分析2016年10月至2020年1月于我院行¹³¹I治疗663例DTC患者，分析其图像信息并详细记录患者相关临床资料，计算¹³¹I治疗后发现转移及其中RAIR-DTC的发生率。对于其中¹³¹I治疗无效的52例RAIR-DTC患者，本研究通过构建Cox风险模型确定预后的独立危险因素，随后根据治疗后5年内疾病是否进展分为进展组及疾病稳定组，通过卡方检验和Logistic回归比较两组间的差异；Kaplan-Meier法（log-rank方法进行检验）评估治疗方法对进展组预后的影响。

结果：663例患者中共有116例（17.5%）在治疗后的碘-131全身显像（Iodine-131 Whole Body Scan， ¹³¹I-WBS）或SPECT/CT中发现淋巴结或远处转移灶，其中52例患者（44.8%）出现¹³¹I抵抗。52例RAIR-DTC患者的3年及5年生存率分别为88.5%、73.1%，进展者分别为81.8%、57.6%，稳定者分别为100%、100%，两组在年龄、是否存在甲状腺外浸润以及首次¹³¹I治疗剂量中存在显著差异（P<0.05）。单因素分析表明患者的年龄、首次¹³¹I治疗前血清刺激性甲状腺球蛋白（preablative stimulated thyroglobulin，ps-Tg）、首次治疗前中性粒细胞与淋巴细胞比值（Neutrophil to Lymphocyte ratio，NLR）及复发转移部位与总生存期显著相关（P<0.05），多因素分析表明年龄>55岁(HR=12.40，95% CI= 2.09 ~ 73.57，P=0.006)、存在远处转移(HR=24.47，95% CI=4.17~143.75，P<0.001)是RAIR-DTC预后的独立危险因素。在进展组行局部手术治疗和/或靶向治疗可明显延长无进展生存期（P<0.001）。

结论：当DTC患者出现远处转移时，发展为RAIR-DTC的风险显著增高。RAIR-DTC的预后较差，高龄及远处转移与不良预后显著相关。高龄、存在甲状腺外浸润的患者可在首次¹³¹I治疗时适当提高治疗剂量延缓疾病进展，出现进展者建议及时行局部手术治疗或/和靶向治疗。

Objective: To analyze the clinical characteristics of disease stability and progression, as well as prognostic factors, in patients with radioiodine-refractory differentiated thyroid cancer (RAIR-DTC).

Methods: A retrospective analysis was conducted on 663 patients with differentiated thyroid carcinoma (DTC) who underwent ¹³¹I therapy at our department from October 2016 to January 2020. Imaging data and detailed clinical information were collected to calculate the incidence of metastases detected after ¹³¹I treatment and the proportion of RAIR-DTC among them. For the 52 patients with RAIR-DTC who showed no response to ¹³¹I therapy, this study established a Cox proportional hazards model to identify independent prognostic risk factors. Patients were categorized into progression and stable groups based on disease progression within five years post-treatment. Differences were analyzed using chi-square tests and logistic regression. The Kaplan-Meier method (with log-rank test) evaluated the impact of treatment on progression group prognosis.

Results: Of the 663 patients, 116 (17.5%) were found to have lymph node or distant metastases on post-therapeutic Iodine-131 whole-body scans (¹³¹I-WBS) or SPECT/CT imaging. Among them, 52 patients (44.8%) were identified as having RAIR-DTC. The 3-year and 5-year survival rates for the 52 RAIR-DTC patients were 88.5% and 73.1%, respectively. In the progression group, the rates were 81.8% and 57.6%, while in the stable group were 100% and 100%. There were significant differences between the two groups in terms of age, presence of extrathyroidal extension, and the initial ¹³¹I treatment dose (P<0.05). Univariate analysis indicated that the age of the patients, preablative stimulated thyroglobulin (ps-Tg) levels before the first ¹³¹I treatment, the neutrophil to lymphocyte ratio (NLR) before the first treatment, and the sites of recurrence and metastasis were significantly associated with overall survival(P<0.05). Multivariate analysis showed that age >55 years (HR=12.40，95% CI= 2.09 ~ 73.57，P=0.006) and distant metastasis (HR=24.47，95% CI=4.17~143.75，P<0.001) were independent risk factors for poor prognosis. Kaplan-Meier curve analysis showed that local surgery and/or targeted therapy significantly prolonged progression-free survival in the progression group (P < 0.001).

Conclusion: The presence of distant metastases in patients with DTC is significantly associated with an increased risk of developing RAIR-DTC. The prognosis for RAIR-DTC is poor, with advanced age and distant metastasis being significantly associated with unfavorable outcomes. In elderly patients and those with extrathyroidal invasion, it may be beneficial to appropriately increase the treatment dose during the initial ¹³¹I therapy to delay disease progression. For patients who experience disease progression, prompt local surgical intervention and/or targeted therapy is recommended.