Analysis Of The Risk Factors Of Occult Lymph Node Metastasis In The Central Region Of Papillary Thyroid Microcarcinoma At Stage CN0

Purpose cN0 Papillary thyroid microcarcinoma has a high rate of lymph node metastasis in the central region.This paper analyzed the risk factors of occult lymph node metastasis in the central region of phase cN0 Papillary thyroid microcarcinoma,and improved the risk assessment system for preoperative lymph node metastasis in the central region of patients with phase cN0Papillary thyroid microcarcinoma.Materials and Methods A retrospective analysis of clinical data of 556 patients with stage cN0 Papillary thyroid microcarcinoma diagnosed in our hospital from February01,2014 to February 01,2019 and dissected lymph nodes in central region was carried out.The occult metastasis of lymph nodes in central region and gender,age,diameter of tumors,type of distribution of tumors,number of tumors and presence or absence of capsules were used.The relationship between external invasion,benign disease,BRAFV600E gene mutation and immunohistochemical expression was analyzed.Results Of 556 patients who underwent central lymph node dissection,167 had metastasis,with a total metastasis rate of 30.04%.Single factor chi-square test showed that the diameter of tumors>5 mm and tumors≤5 mm(45.37%vs21.08%,P<0.001),invasion of envelope and no invasion of envelope 52.11%vs22.46%,P<0.001),number of tumors>2 and single focus(55.84%vs20.15%,P<0.001),mutation of BRAFV600E gene(+)and mutation of BRAFV600E gene(-)(32.78%vs11.27%,P=0.038)were associated with occult metastasis of central lymph nodes.The shift was significantly correlated.However,sex,age,lesion distribution,presence or absence of thyroid benign diseases,and expression of immunohistochemical markers were not significantly correlated with lymph node metastasis in the central region before operation(P>0.05).Multivariate logistic regression analysis showed that tumor diameter>5mm(P<0.001,OR=2.271),capsular invasion(P<0.001,OR=2.506),number of tumors>2(P<0.001,OR=4.763),BRAFV600E mutation(+)(P<0.001,OR=6.236)were independent risk factors for occult lymph node metastasis in central region.A single factor chi-square test was performed in 154 patients with multifocal cancer.It was found that bilateral cancer(χ~2=7.928,P=0.005)was a risk factor for lymph node metastasis in the central region.One-way chi-square test showed that the lower pole(χ~2=25.061,P<0.001)was a risk factor for lymph node metastasis in the central region in 402 patients with single focus cancer.Univariate chi-square test was used in 97 patients with tumor diameter>5mm with capsular invasion.Benign diseases and non-benign diseases(30.00%vs59.65%,P<0.05)were found to affect lymph node metastasis in the central region.Logistic regression analysis showed that benign diseases(P=0.020,OR=0.306)were lymph node metastasis in the central region of patients with tumor diameter>5mm with capsular invasion.Protective factors.Single-factor chi-square test was used in 351 patients with tumors less than 5 mm in diameter.The results showed that envelope invasion was significantly correlated with non-envelope invasion(62.22%vs15.03%,P<0.001),multiple and single focus(58.02%vs10.00%,P<0.001)and concealed lymph node metastasis in central region.Multivariate logistic regression analysis showed that age under 55(P=0.002,OR=3.678),envelope invasion(P<0.001,OR=10.343)multiple(P<0.001,OR=16.592)were significantly correlated with concealed lymph node metastasis in central region.were independent risk factors for occult lymph node metastasis in central region of patients with tumor diameter less than 5 mm.Conclusion The incidence of occult lymph node metastasis was 30.04%in patients with stage cN0 Papillary thyroid microcarcinoma.The risk factors of occult lymph node metastasis were tumor diameter>5mm,invasion of capsule,number of lesions>2 and BRAFV600E mutation in gene detection.Benign thyroid disease is a protective factor for lymph node metastasis in patients with tumor diameter>5mm and capsular invasion.For patients whose diameter of tumors is less than 5 mm,male and the number of lesions(>2)and the invasion of the capsule are risk factors for occult lymph node metastasis in the central region.Preventive central lymphadenectomy is recommended for patients with stage cN0 Papillary thyroid microcarcinoma combined with the above risk factors.