Abstract：
Background: Calcitonin measurement is widely used in the diagnosis, prognosis, and follow-up of patients with medullary thyroid carcinoma (MTC). The prognostic value of undetectable postoperative calcitonin (POCal) in long-term disease outcomes remains uncertain. Objective: The aim of this study is to evaluate POCal as a prognostic marker for long-term MTC disease status. Methods: A retrospective cohort study was carried out. We collected data from the medical records of patients with MTC attending two tertiary teaching hospitals. Patients were divided according to POCal into two groups: undetectable (below the detection limit) or detectable. The outcome was determined at the last medical visit and defined as disease free (undetectable calcitonin and no evidence of disease on imaging), persistent disease (detectable calcitonin with or without structural disease), or disease-related death. Results: Three hundred thirty-four MTC patients were included in the study. The mean age at diagnosis was 41.1 ± 18.6 years; 202 patients (60.5%) were women; and 167 patients (50.0%) had sporadic MTC. The median tumor size was 2.0 cm (1.1-3.5 cm); 164 patients (49.1%) had lymph node metastasis and 63 patients (18.9%) had distant metastasis. At the first postoperative evaluation (3-6 months after surgery), 141 patients had undetectable POCal (mean age = 37.9 years, 70.9% women, median tumor size 1.5 cm [0.7-2.5 cm]; 28 [19.9%] had lymph node metastasis and none had distant metastasis). After a median follow-up of 7.7 years (2.1-13.2 years), 127 (90.1%) of these patients were free of disease, whereas 14 (9.9%) had persistent biochemical disease with stable calcitonin levels. No patient with undetectable POCal died of the disease. In the detectable POCal group (mean age = 42.9 years, 52.8% women, median tumor size 3.0 cm [1.8-4.2 cm]; 136 [70.5%] had lymph node metastasis and 63 [32.6%] had distant metastasis), 18 (9.2%) patients achieved disease-free status, 51 (26.6%) had biochemical disease, and 61 (31.6%) had persistent structural disease. Sixty-three (32.6%) patients died of disease-related events. Further analysis using a multivariate model identified undetectable POCal as an independent prognostic variable for disease-free status (HR = 5.33, CI = 2.86-9.94; p < 0.001). Conclusions: POCal is a strong prognostic marker for long-term disease-free survival and might help define follow-up strategies for MTC patients.
摘要：
背景:降钙素的测定被广泛应用于诊断,预后,并对甲状腺髓样癌（MTC）患者进行随访。无法检测的术后降钙素（POCal）在长期疾病结局中的预后价值仍不确定。目的：本研究的目的是评估POCal作为长期MTC疾病状态的预后指标。方法：采用回顾性队列研究。我们从两家三级教学医院的MTC患者的病历中收集数据。根据POCal将患者分为两组：不可检测（低于检测极限）或可检测。在最后一次就诊时确定结果，并定义为无病（无法检测到降钙素，影像学上无疾病迹象）。持续性疾病（可检测的降钙素伴或不伴结构性疾病），或疾病相关的死亡。结果：研究中纳入了303例MTC患者。诊断时的平均年龄为41.1±18.6岁；202例患者（60.5%）为女性；167例患者（50.0%）有散发性MTC。中位肿瘤大小为2.0cm（1.1-3.5cm）；164例（49.1%）有淋巴结转移，63例（18.9%）有远处转移。在术后第一次评估时（手术后3-6个月），141例患者未检测到POCal（平均年龄=37.9岁，70.9%女性，中位肿瘤大小1.5cm[0.7-2.5cm];28[19.9%]有淋巴结转移，无远处转移）。在中位随访7.7年（2.1-13.2年）后，这些患者中有127例（90.1%）没有疾病，而14（9.9％）的生化疾病持续存在，降钙素水平稳定。没有检测不到POCal的患者死于该疾病。在可检测的POCal组中(平均年龄=42.9岁，52.8%女性，中位肿瘤大小3.0cm[1.8-4.2cm]；136[70.5%]有淋巴结转移，63[32.6%]有远处转移），18例（9.2％）患者达到无病状态，51（26.6%）有生化疾病，61（31.6％）患有持续性结构性疾病。63例（32.6%）患者死于疾病相关事件。使用多变量模型的进一步分析将未检测到的POCal确定为无病状态的独立预后变量（HR=5.33，CI=2.86-9.94；p<0.001）。结论：POCal是长期无病生存的强大预后指标，可能有助于确定MTC患者的随访策略。
