Analysis Of Lymph Nodes Metastatic Risk Factors In Papillary Thyroid Carcinoma And Its Impact On Neck Dissection

[Objective] Papillary thyroid carcinoma (PTC) is the most common pathological type ofthe thyroid malignancy with the biological characteristics of slower growth, better prognosis.However, neck lymph node metastasis is common PTC, and the neck residual metastaticlymph node is the most common cause of recurrence. Studies have shown that neck lymphnode metastasis rate of PTC after operation was up to5.4-13%. Although cervical lymph nodemetastasis in PTC does not affect the overall prognosis, but research showed that lymph nodedissection could reduce local recurrence rate and prolong the survival period of patients withhigh risk. Therefore, postoperative control of local lymph node recurrence in PTC patients hasbecome the main concern of clinicians.Thyroid lymph system drainage pattern is unique. Therefore, lymph node metastasis isrelatively predictable. The majority of central lymph node metastasis of PTC often occur firstipsilateral area near and anterior to the trachea, which can then be transferred to the ipsilaterallateral cervical lymph node. And skip metastasis (LLNM without CLNM) are uncommon.Now thyroid operation extent and whether lymph node dissection should be performed hasbasically reached an agreement, but the lymph node dissection extent remains controversial.So a better analysis of PTC lymph node metastasis is helpful to clinical decision of lymphnode dissection.[Methods] The study subjects were1829patients all treated at the Department ofThyroid Surgery,1st Hospital of the Jilin University,Changchun, China, from July2008toJuly2012. The patients included in the study met the following criteria: All patients providedwritten informed consent for their information to be stored in the hospital database and usedfor research. All patients were diagnosed as PTC by pathological department. Patients withprevious thyroid surgery, radiotherapy history and distant metastasis were excluded. Frozenpathological section was used to guide the extent of operation resection. In1829patients,1555patients met the criteria. In1555patients,151cases of patients were performed lateralcervical lymph node dissection. We Statistical analyzed risk factors of CLNM and LLNM inPTC. At the same time we analyzed the rule of neck lymph node metastasis in PTC patients. [Result] The1555cases of patients aged14to85, the average age was43.25±10.38;male267cases, female1388cases; The ratio of men to women was1to5.2. The largesttumor was8.0cm, minimum was less than0.1cm; the number of tumors1-8, average1.62;504cases of bilateral,1051cases of unilateral;713cases of CLNM in1555, the metastasisrate45.85%,109cases of LLNM in151, the metastasis rate72.19%; the number of thecentral lymph node1-87, average positive number5.46(1-46), the number of the laterallymph node3-55, average positive number4.77(1-14).788cases of nodular goiter.104casesof thyroid adenoma.607cases of lymphocytic thyroiditis. The CLNM rate of PTC is higher inmale gender, younger age (≤45yr of age), extrathyroidal extension, larger size of the primarytumor (10mm),bilateral cancer, not accompanied with nodular goiter and thyroid adenomagroups. Our multivariate logistic regression analysis found male gender, younger age (≤45yrof age), extrathyroidal extension, and larger size of the primary tumor (10mm) to be riskfactors of CLNM.(odds ratio2.089,2.417,1.534,3.079). The LLNM rate of PTC is higher inmale gender, younger age (≤45yr of age), mutifocal, extrathyroidal extension, larger size ofthe primary tumor (10mm) groups. Our multivariate logistic regression analysis found CLNMpositive was risk factor of LLNM.(odds ratio4.996).3.With the increase of the number ofpositive lymph nodes, LLNM positive rate showed an upward trend.4.In109cases of lateralcervical lymph node positive patients, we found that the level IV is the most vulnerable area,followed by the level III, level II, finally level V.[Conclusion]1. Male gender, younger age (≤45yr of age), extrathyroidal extension, andlarger size of the primary tumor (10mm) are risk factors of CLNM.2. CLNM positive is riskfactor of LLNM. With the increase of the number of positive lymph nodes, lateral cervicallymph node metastasis positive rate show an upward trend.3. Incidences of node involvementin level VI and level II-V are both significant. In LLNM positive patients, the level IV is themost vulnerable area, followed by the level III, level II, finally level V. Level I lymph nodesmetastasis is not common.4. PTC patients should be performed prophylactic central lymphnode dissection during first treatment. CLNM positive patients especially with more positivelymph nodes（≥3）should be performed ipsilateral II-V lymph node dissection.