Risk Factors Of Lateral Lymph Node Metastasis In Unifocal Papillary Thyroid Microcarcinoma

ObjectiveThyroid carcinoma is the most common primary endocrine malignancy,while thyroid papillary carcinoma is the most common pathological type of thyroid malignancy.It mainly spreads to the surrounding cervical lymph nodes,and cervical lymph node metastasis is also an important factor affecting the prognosis of patients with thyroid carcinoma.More and more evidences showed that cervical lymph node metastasis can cause poor prognosis in patients,so the prognosis can be effectively improved if there is a complete resection of the primary tumor and metastatic lymph nodes.But the cervical lymph nodes are always difficult to detect and diagnose.Large number of literatures have reported that the characteristic of the multifocality is an important risk factor for cervical lymph node metastasis.Multifocality means the dissemination of the tumor within the gland,which indicates that the tumor cells are prone to drop from the primary lesion and then spread throughout the gland and even spread to the cervical lymph node through lymphatic vessels.Therefore,this study excluded multifocality,the most accepted malignant characteristic,and explored the regular metastasis pattern of thyroid papillary microcarcinoma from the perspective of the other clinical and pathological features,so as to facilitate clinicians to formulate better treatment policies and surgical plans.MethodsThis study retrospectively analyzed the clinical data of 6923 patients with papillary thyroid carcinoma who underwent thyroid surgery in the First Hospital of Jilin University from January 2015 to June 2018.After strict screening,850 patients met the criteria and were included in the study,including 32 patients with lateral cervical lymph node metastasis.850 patients with unifocal papillary thyroid microcarcinoma were divided into two groups according to whether there was lateral cervical lymph node metastasis or not.Then analyze the clinical characteristics such as gender,age(The patients were divided into<55 years old group and>55 years old group according to the eighth edition of AJCC thyroid carcinoma TNM staging system.),diameter of the lesion(<0.5cm group and ≥0.5cm group),capsule invasion,with Hashimoto’s thyroiditis,and central lymph node metastasis.SPSS 20.0 statistical analysis software was used for data analysis.ResultsIn this study,univariate analysis revealed that lateral lymph node metastasis was significantly associated with cervical lymph node metastasis,gender,age,capsule invasion,Hashimoto’s thyroiditis and central lymph node metastasis(P<0.05).Then logistic regression analysis was used to analyze the above factors.Male(OR=3.263,95%C.I.1.405—7.578),capsule invasion(OR=8.416,95%C.I.1.862—38.042),with Hashimoto’s thyroiditis(OR=3.314,95%C.I.1.448—7.581),central lymph node metastasis(OR=11.905,95%C.I.4.318—32.826),diameter of lesion(OR=0.054,95%C.I.0.009—0.307).All of them were independent risk factors for lateral lymph node metastasis in unifocal papillary thyroid microcarcinoma.The ROC curve was used for analyzing the relationship between number of central lymph node metastases and the lateral cervical lymph nodes metastases.The area under the curve was 0.756(P=0.000,95%C.1.0.664-0.849),which had diagnostic value.ConclusionsMale,age(≥55 years old),tumor diameter(≥5mm),capsule invasion,with Hashimoto’s thyroiditis and central lymph node metastasis(≥3)were the risk factors for lateral lymph node metastasis of unifocal papillary thyroid microcarcinoma.The number of central lymph node metastasis was positively correlated with the metastasis in lateral cervical lymph node,which could be used as a predictor of lateral lymph node metastasis.Skip metastasis is relatively rare,but it can not be ignored.It often metastases to the lymph nodes in the Ⅲ level and Ⅳ level.The frequency of lateral lymph node metastasis was Ⅲlevel>Ⅳ level>Ⅱ level>Ⅴ level,and metastasis in Ⅰ level seldom occurs.