AIM The risk of differentiated thyroid cancer (DTC) recurrence is widely evaluated according to the 2015 ATA Risk Stratification System. Topography of malignant nodules has been previously reported as an additional risk factor but is not included in the ATA system. Thus, our study aimed to evaluate the relationship between DTC topography and response to initial therapy. PATIENTS AND METHODS We enrolled 401 low- to intermediate-risk patients with DTC who had undergone thyroidectomy and radioiodine therapy. DTC topography was recorded and compared with the response to therapy as assessed 12 months after the end of therapy. RESULTS Overall, 366/401 (91.3%) patients had an excellent response to initial therapy while 22/401 (5.5%) and 13/401 (3.2%) had incomplete biochemical or structural responses, respectively. Incomplete response occurred in 10/36 (27.8%), 5/125 (4.0%), and 4/111 (3.6%) patients whose unifocal malignant nodules were located in the isthmus, right lobe, or left lobe. Incomplete response was also observed in 4/54 (7.4%) and 12/75 (16%) patients carrying multifocal cancers in one or both lobes, respectively. Patients with isthmic cancer more frequently demonstrated incomplete response compared with those who had cancer in other locations (P = 0.00). No significant relationship was found with age, gender, maximum size of malignant nodule, Hashimoto's thyroiditis, vascular invasion, and extrathyroidal extension (P = 0.78, P = 0.77, P = 0.52, P = 0.19, P = 0.73, and P = 0.26, respectively). The risk of incomplete response was about 65% higher in patients with isthmic lesions compared with other patients (odds ratio = 6.725). A log-rank test demonstrated that disease-free survival (DFS) of patients with isthmic lesions was significantly shorter than that of other patients (P = 0.02). CONCLUSION Our data show that isthmus topography of malignant thyroid nodules is a risk factor for having both persistent disease 12 months after primary treatment and reduced DFS.

中文翻译：

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峡部地形是分化型甲状腺癌患者持续疾病的危险因素。

目的 分化型甲状腺癌 (DTC) 复发的风险根据 2015 年 ATA 风险分层系统得到广泛评估。以前曾报道恶性结节的地形是一个额外的危险因素，但不包括在 ATA 系统中。因此，我们的研究旨在评估 DTC 地形与初始治疗反应之间的关系。患者和方法 我们招募了 401 名接受过甲状腺切除术和放射性碘治疗的中低危 DTC 患者。记录 DTC 地形，并与治疗结束后 12 个月评估的治疗反应进行比较。结果 总体而言，366/401 (91.3%) 患者对初始治疗有很好的反应，而 22/401 (5.5%) 和 13/401 (3.2%) 分别有不完全的生化或结构反应。不完全反应发生在 10/36 (27.8%)、5/125 (4.0%) 和 4/111 (3.6%) 的单灶性恶性结节位于峡部、右叶或左叶的患者中。分别在 4/54 (7.4%) 和 12/75 (16%) 的单叶或双叶携带多灶性癌症的患者中也观察到不完全反应。与其他部位的癌症患者相比，峡部癌患者更频繁地表现出不完全反应（P = 0.00）。与年龄、性别、恶性结节最大大小、桥本氏甲状腺炎、血管侵犯和甲状腺外扩展无显着相关性（P = 0.78、P = 0.77、P = 0.52、P = 0.19、P = 0.73 和 P = 0.26 ， 分别）。峡部病变患者的不完全反应风险比其他患者高约 65%（优势比 = 6.725）。对数秩检验表明峡部病变患者的无病生存期（DFS）明显短于其他患者（P = 0.02）。结论 我们的数据表明，恶性甲状腺结节的峡部地形是初次治疗 12 个月后疾病持续存在和 DFS 降低的危险因素。