The Clinical Significance Of Lymph Node Dissection In The Central Region Of Stage CN0 Thyroid Micro-papillary Carcinoma

Background: Papillary Thyroid micro-carcinoma(PTMC)commonly refers to thyroid cancer which are less than 1.0 cm in diameter.Although it has better prognosis,low malignancy,and tends to be conservative treatment clinically,local tissue invasion and lymph node metastasis also occurs.In recent years,the widespread application of ultrasound technology has greatly enriched the detection methods of thyroid microcarcinoma,thereby increasing its incidence There is a lot of controversy in the current clinical surgical treatment about PTMC,especially for the negative lymph node(cN0)after imaging studies.Unfortunately,there is no specific surgical strategy has been reported in national and international guidelines.Objective: The purpose of this study was to investigate the clinical significance of Central Lymph Node Dissection(CLND)during cN0 stage PTMC surgery,the risk factors for central lymph node metastasis,the specific scope of central lymph node dissection,and the incidence of postoperative complications.This work will provide a theoretical basis for clinical individualized treatment of PTMC.Methods: The clinical data of 207 patients with stage cN0 PTMC who were eligible and first-time enrolled in the thyroid surgery department of Subei People's Hospital from November 2016 to November 2018 were retrospectively analysed,the effect of age,gender,tumour size,tumour morphology from imaging study on the lymph node metastasis rate in the central region were investigated.At the same time,prospectively,68 cases of cN0 stage PTMC patients in our hospital from November 2018 to November 2019 were treated with thyroid cancer resection + central lymph node dissection.During the operation,the central lymph nodes were divided into pre-laryngeal lymph nodes(a),pretracheal lymph nodes(b),superficial lymph nodes of the recurrent laryngeal nerve(c),deep lymph nodes of the recurrent laryngeal nerve(d),and upper sternal lymph nodes(e).The above areas were cleaned and sent for postoperative pathological examination respectively.Based on the results,the coincidence rate of cN0 and p N0,metastasis rate of each lymph node group,the incidence of recurrent laryngeal nerve injury and postoperative blood calcium reduction were counted and analyzed.Results: In a retrospective study,among the 207 patients with stage cN0,the number of lymph node metastases in the central region was 63(30.4%).The metastasis of lymph nodes in the central region of papillary thyroid carcinoma was related to gender,age,and tumor size and the difference was statistically significant(P <0.05).In prospective study,the metastatic rate of central node lymph nodes in 68 patients was 42.6%,and the coincidence rate between cN0 and p N0 was 57.4%.The lymph node metastasis rates in each group were: 0 %(a),22.1 %(b),14.7 %(c),10.3 %(d),0 %(e).Studies on postoperative complications have shown that all patients had no incision infection or postoperative bleeding.However,there were five patients(7.4 %)had transient recurrent laryngeal nerve palsy after surgery,and one patient(1.5 %)had permanent recurrent laryngeal nerve injury;15 patients(22.1 %)had temporary hypocalcemia within 1 week after operation,and 3(4.4%)had permanent hypocalcemia.Conclusion: Prophylactic CLND for patients with cN0 stage PTMC is reasonable.and the management strategy during dissection should be: It is recommended that unilateral prophylactic CLND should be performed on male PTMC patients with tumour diameter > 5mm,age ? 55 years,and a higher risk of recurrence.The management strategy for dissection should be as follows: unilateral prophylactic CLND is recommended for male PTMC patients with tumour diameter> 5mm,age ? 55 years,and high risk of recurrence.The focus of dissection should be on: pretracheal lymph nodes,deep recurrent laryngeal nerves and superficial lymph nodes of the recurrent laryngeal nerve,do not simplify and omit during cleaning,which is not simplified or omitted,while anterior laryngeal lymph nodes and superior sternum fossa lymph node can be left untreated because of the relatively lower metastasis rates.Aiming at thepostoperative complications of prophylactic CLND,during clinical operation,the benefits and risks after cleaning should be measured,and individualized surgical plans should be customized.