Analysis Of Risk Factors For Cervical Lymph Node Metastasis And Postoperative Recurrence Of Medullary Thyroid Carcinoma

BackgroundMedullary thyroid carcinoma(MTC)is a malignant tumor originating from parafollicular cells(C cells)of the thyroid,accounting for about 1%～2%of all thyroid cancers,but compared with Differentiated thyroid cancer(DTC),MTC is highly invasive and has a poor prognosis.The number of deaths accounted for approximately 13.4%of all thyroid cancer-related deaths,especially for patients with cervical lymph node metastasis,the risk of postoperative recurrence and metastasis is higher.Compared with DTC,MTC has the characteristics of non-iodine,unable to receive postoperative thyroid stimulating hormone(TSH)inhibition therapy,and its treatment mainly depends on surgery.This study aims to study the clinical case data of MTC patients,To explore the risk factors of central lymph node metastasis(CLNM)and lateral cervical lymph node metastasis(LLNM)and postoperative recurrence of this disease,so as to guide clinical diagnosis and treatment.ObjectiveBy collecting and studying the clinical case data of MTC patients,the basic clinical characteristics of MTC patients were analyzed,and the risk factors affecting CLNM and LLNM and postoperative recurrence of MTC patients were further studied.MethodsThe clinic-pathologic data of 109 patients diagnosed with MTC after primary surgery admitted to our hospital from June 1,2015 to June 1,2021 were collected and the following data of each patient were recorded:gender,age,maximum tumor diameter,number of cancer foci,unilateral and bilateral cancer foci,extrathyroidal extension(ETE),postoperative CLNM and LLNM,total number of metastatic lymph nodes,total number of resected lymph nodes,lymph node ratio(LNR),preoperative and postoperative serum calcitonin(Ctn)levels.When the number of cancer foci was two or more,it was considered to be multifocal cancer,and the LNR was the ratio of the total number of metastatic lymph nodes to the total number of resected lymph nodes.Statistical analysis of the data differen ces between the two groups with or without lymph node metastasis was conducted to explore the clinical characteristics of lymph node metastasis in MTC patients.Postoperative follow up of MTC patients was conducted through follow-up medical records and telephone calls,and relevant data were collected.The recurrence and recurrence-free survival(RFS)were recorded.RFS was defined as the time from thyroidectomy to recurrence or the last follow-up.Recurrence includes local recurrence and distant metastasis(DM).Univariate and multivariate Logistic regression analysis was used to explore the risk factors affecting CLNM and LLNM in MTC patients;univariate and multivariate COX proportional hazards models were used to analyze the relationship between relevant clinicopathological characteristics and recurrence,and to explore the relevant factors affecting RFS,and the Kaplan-Meier method was used to draw Recurrence-free survival curve,log-rank test to compare the difference between the two survival curves.P<0.05 was considered statistically significant difference.Results1.By analyzing the data between the two groups of MTC patients with or without CLNM,there were statistically significant differences in ETE(P=0.016)and preoperative Ctn≥1000pg/ml(P<0.001)between th e two groups in the univariate Logistic regression analysis.The significant factors in univariate analysis were included in multivariate logistic regression analysis,and it showed that ETE(P=0.033)and preoperative Ctn≥1000pg/ml(P=0.002)were independent risk factors for CLNM in MTC patients.2.The data between the two groups of MTC patients with and without LLNM were analyzed:in the univariate Logistic regression analysis,ETE(P=0.007),preoperative Ctn≥1000pg/ml(P=0.002),CLNM(P<0.001),the largest tumor Diameter≥20mm(P=0.042)had a statistically significant difference between the two groups.Incorporating meaningful factors in univariate analysis into multivariate logistic regression analysis showed that:CLNM(P=0.001)and preoperative Ctn≥1000pg/ml(P=0.042)were independent risk factors for LLNM in MTC patients.3.The last follow-up was on December 31,2021,and the median follow-up time of 109 patients was 39 months(5-90 months).During the follow-up period,24 patients developed recurrence(3 distant metastasis and 21 cervical lymph node metastasis),with a recurrence rate of 22.0%and an overall 5-year recurrence free survival rate of 75.4%.The results of univariate COX regression analysis showed that:There were statistically significant differences in ETE(P=0.001),CLNM(P=0.017),LLNM(P<0.001),postoperative Ctn biochemical recovery(P=0.001)and higher LNR(LNR≥0.35)(P<0.001)between the two groups.The significant factors in univariate analysis were included in multivariate COX regression analysis,and it showed that ETE(P=0.014),LLNM(P=0.007)and high LNR(LNR≥0.35)(P=0.001)were independent risk factors for postoperative recurrence in MTC patients.Further stratified analysis was conducted according to the number of patients with independent risk factors,and the results showed that the 5-year recurrence free survival rates of patients with 0,1,2 and 3 risk factors were 100%,71.0%,50.5%and 14.3 respectively.Conclusion1.MTC patients with ETE and preoperative Ctn≥1000pg/ml are more likely to develop CLNM,and the central lymph nodes should be dissected more carefully during the operation.2.MTC patients with CLNM and preoperative Ctn≥1000pg/ml have a higher incidence of LLNM,and prophylactic lateral neck lymph node dissection can be considered at this time,which provides a reference for the clinical individualized treatment of such patients.3.ETE,LLNM and high lymph node ratio(LNR≥0.35)are independent risk factors for postoperative recurrence of MTC patients,and long-term follow-up monitoring should be emphasized after surgery.