1 Department of Oncology, University of Alberta Faculty of Medicine and Dentistry , Edmonton, Canada .
2 Department of General Surgery, University of Alberta Faculty of Medicine and Dentistry , Edmonton, Canada .
Thyroid. 2018 Jul;28(7):902-912. doi: 10.1089/thy.2017.0136.
The application of radioactive iodine in differentiated thyroid carcinomas has become more selective in an attempt to decrease morbidity. While ablative success has been documented, it is less clear how changes in radioactive iodine treatment strategies will influence long-term recurrence rates for patients with larger tumors and adverse pathological features, including extrathyroidal extension and nodal metastases.
Patients diagnosed between 1995 and 2008 with differentiated thyroid carcinoma treated with thyroidectomy followed by radioactive iodine treatment were eligible. All patients were followed for a minimum of five years using a standardized follow-up protocol requiring both biochemical and imaging assessments for recurrent disease (n = 219). Patients were stratified by initial radioactive iodine activity, and disease-free survival was calculated using the Kaplan-Meier method, with significant differences defined by the log-rank test.
In this cohort, 46% of patients had clinical metastases and 74% had primary tumors >1.5 cm. Patients who had recurrences were more likely to present with extrathyroidal extension (p = 0.002) and lymph node metastases at diagnosis (p < 0.001). Patients presenting with both extrathyroidal extension and lymph node metastases had a significantly worse time to progression if treated with <1850 MBq radioactive iodine compared to those patients treated with >1850 MBq (25 months vs. 121 months; p = 0.004). The use of lower-activity radioactive iodine ablative therapy was associated with more early recurrences (p = 0.003). Being aged younger or older than 45 years did not impact the time to recurrence nor did the use of level 6 dissection. On multivariate analysis, lymph node metastases at diagnosis and multiple applications of radioactive iodine were linked to increased risk of recurrence. Patients with neither, or only one, adverse pathologic feature had excellent outcomes, regardless of initial ablative activity, with <10% of patients recurring over a 10-year time span.
Recurrent disease in differentiated thyroid carcinoma is more common in patients treated with low-activity radioactive iodine in patients with lymph node metastases and extrathyroidal extension. These recurrences typically occur within four years of initial treatment. Patients lacking both of these risk factors treated with low radioactive iodine activity (<1850 MBq) have excellent outcomes, even after 10 years.
为降低发病率，分化型甲状腺癌的放射性碘应用已变得更具选择性。虽然消融效果已得到证实，但对于肿瘤较大且具有不良病理特征（包括甲状腺外侵犯和淋巴结转移）的患者，改变放射性碘治疗策略将如何影响其长期复发率尚不清楚。
本研究纳入了 1995 年至 2008 年间接受甲状腺切除术联合放射性碘治疗的分化型甲状腺癌患者。所有患者均采用标准化随访方案进行至少 5 年的随访，该方案要求对复发疾病进行生化和影像学评估（n=219）。根据初始放射性碘活度对患者进行分层，并使用 Kaplan-Meier 法计算无病生存率，差异有统计学意义的定义为对数秩检验。
在该队列中，46%的患者有临床转移，74%的患者原发肿瘤>1.5cm。有复发的患者更有可能在诊断时出现甲状腺外侵犯（p=0.002）和淋巴结转移（p<0.001）。与接受>1850MBq 放射性碘治疗的患者相比，如果接受<1850MBq 放射性碘治疗的患者同时存在甲状腺外侵犯和淋巴结转移，其进展时间明显更差（25 个月比 121 个月；p=0.004）。低活性放射性碘消融治疗的应用与更早的复发相关（p=0.003）。年龄<45 岁或>45 岁与复发时间无关，6 级解剖也无关。多变量分析显示，诊断时存在淋巴结转移和多次应用放射性碘与复发风险增加相关。无不良病理特征或仅有一个不良病理特征的患者具有极好的结果，无论初始消融活性如何，在 10 年时间跨度内，<10%的患者复发。
在有淋巴结转移和甲状腺外侵犯的患者中，接受低活性放射性碘治疗的分化型甲状腺癌患者更常发生复发性疾病。这些复发通常发生在初始治疗后 4 年内。缺乏这两个危险因素且接受低放射性碘活性（<1850MBq）治疗的患者具有极好的结果，即使在 10 年后也是如此。
