Necessity Of Contralateral Central Lymh Node Dissection In CN0 Unilateral Papillary Thyroid Microcarcinoma

Objective:Papillary thyroid microcarcinoma is a subtype of papillary thyroid cancer, accounting for 6% to 35% of thyroid cancer. Papillary thyroid microcarcinoma is characterized by small and occult lesions and symptomless, therefore often not easy to be found before surgery, usually found combination with benign thyroid diseases during operation. With the improvement of clinical diagnostic technology and people’s growing awareness of health. Accompanied by thyroid ultrasound examination as a part of physical examinations and the applications of fine needle aspiration biopsy particularly, the detection rate of papillary thyroid microcarcinoma are increasing and the incidence rate of papillary thyroid microcarcinoma is growing by about 6 percent every year. Papillary thyroid microcarcinoma is characterized by occult onset, long duration, low grade and higher lymph node metastasis tendency. Operation is the main treatment for papillary thyroid microcarcinoma and surgeons choose reasonable operating way according to the pathologic results during surgery. Experts have reached a consensus that combined radical surgery is applicable for patients with papillary thyroid carcinoma those clinically cervical lymph node-positive. There are still disputes for patients with papillary thyroid carcinoma those clinically cervical lymph node-negative, for example, selective neck dissection whether or not, surgical scope, surgical timing. To analyze the clinical data of the patients with c N0 unilateral papillary thyroid microcarcinoma and to disguss the reasonable solution of cervical lymph node dissection. Methods:Retrospectively analyze the clinical data of 186 patients with c N0 unilateral papillary thyroid microcarcinoma treated in Jinan military general hospital(108 cases) and the second people’s hospital of Liaocheng(78 cases)from January 2008 to December 2012 and the patients were followed up. All the patients underwent total thyroidectomy and bilateral central lymph node dissection. The related factors(age, tumor size, tumor location, thyroid capsular invasion and tumor complete envelope included) of contralateral central lymph node metastasis were studied and the necessity of contralateral central lymph node dissection in c N0 unilateral papillary thyroid microcarcinoma were evaluated. All patients received postoperative endocrine therapy and periodic neck ultrasound for tracking cervical lymph node metastasis. Results:The average detection rate of lymph node metastasis was 3 on the left side and 4 on the right side. Central lymph node metastasis of 83 cases were positive(rate for 44.62%). 2 cases with tumor location near the isthmus found contralateral lymph node metastasis(rate for 1.08%), those without ipsilateral lymph node metastasis. The rate of ipsilateral central lymph node metastasis was 43.55%(81/186) and contralateral central lymph node metastasis for 11.83%(22/186). Details in Table 1. Risk factors of cervical lymph node metasasis for those with c N0 unilateral papillary thyroid microcarcinoma include age, thyroid capsule invasion, complete tumor capsule, tumor location and tumor size. 4 cases with postoperative recurrent laryngeal nerve palsy, the rate was 2.15%(4/186). The recurrent laryngeal nerve of one case were cut off during surgery which were invaded by tumor and 3 cases injured during tracheo- esophageal groove lymph node dissection. 71 cases were found postoperative hypo- calcemia, serum parathyroid hormone below the lower limit of the reference value, and PTH of 69 cases returned to normal after treatment. 2 cases with permanent hypo- parathyroidism, the reason may be associated with that autologous transplantation of parathyroid failed to play the role. Conclusion:Total thyroidectomy and bilateral central lymph node dissection is feasible and safe and important for the patients with c N0 unilateral papillary thyroid microcarcinoma, who meet one of the following conditions, Such as, age≥45 years, thyroid capsule invasion, incomplete tumor capsule, tumor location near thyroid isthmus or the bottom pole, tumor maximum diameter greater than 5 mm. On the contrary, ipsilateral gland and isthmus resection and ipsilateral central lymph node dissection are proposed, to prevent postoperative complications and poor compliance for those with endocrine suppression therapy.