Analysis Of Risk Factors For Cervical Lymph Node Metastases In Sporadic Medullary Thyroid Carcinoma

ObjectiveMedullary thyroid carcinoma(MTC)is one of the thyroid tumors formed by the malignant proliferation and differentiation of C cells and the adjacent cells of the thyroid gland,approximately 2%of all thyroid malignancies.Prognosis of medullary thyroid carcinoma is worse,and occurrence of early metastasis is easy.C cells can secrete a variety of biological active substances such as calcitonin,adrenocorticotropic hormone,prostaglandin and serotonin.Therefore,in addition to clinical manifestations such as thyroid nodules and cervical lymph node metastases,there are some endocrine symptoms.About 30%of patients have a history of chronic diarrhea,accompanied by facial flushing and other similar cancer syndromes.This is because tumors secrete 5-tryptamine and the prostate,which promotes the acceleration of intestinal peristalsis.These symptoms can disappear after removal of the thyroid primary tumor and cervical metastases.The common metastasis pathway is lymphatic and hematogenous metastasis.If cervical lymph nodes metastasize,it can have a quickly capsule besides the surrounding tissue.Compared with other thyroid cancers,MTC has unique biological characteristics and is insensitive to radiotherapy,chemotherapy and iodine therapy.Surgical intervention is currently the only effective,curative treatment for medullary thyroid cancer.The 2015 American Thyroid Association recommended total thyroidectomy and different range of lymph node dissection,but controversy remains surrounding the indication for prophylactic lateral lymph node dissection.This study was performed to analyze the risk factors for cervical lymph node metastases and predict the indication for prophylactic lateral neck dissection in patients with sporadic medullary thyroid carcinoma(SMTC).MethodsA total of 65 cases of SMTC which were first treated between January 2007 and January 2017 were reviewed retrospectively.Univariate analysis with χ2 test and multiple logistic regression analysis were applied to identify the clinicopathological features(sex,age,tumor size,number of tumor foci,capsule or vascular invasion,and so on)related to cervical lymph node metastases.ResultsMetastases rates in central and lateral compartment were 46.2%(30/65)and 40.0%(26/65),respectively.Univariate analyses showed the incidence of cervical lymph node metastases was significantly higher in patients with tumor size>1cm,tumor multifocality and thyroid capsule invasion.Multivariate analyses revealed that only thyroid capsule invasion was an independent predictive factor for central compartment metastases(p<0.001,OR=11.080)and lateral neck metastases(p<0.001,OR=9.067).Moreover,the possibility of central compartment metastases was higher when preoperative value of serum carcinoembryonic antigen(CEA)was above 30 ng/mL(60%vs 34.3%,χ2=4.298,P=0.038).ConclusionsThe medullary thyroid carcinoma has a high incidence of cervical lymph node metastases.Prophylactic lateral node dissection is necessary in patients with thyroid capsule invasion or with high value of serum carcinoembryonic antigen(CEA).