Predictive Factors Of Contralateral Central Lymph Node Metastasis In Unilateral Papillary Thyroid Carcinoma

Objectives:To evaluate the predictive factors for contralateral central lymph node metastasis in patients with unilateral differentiated thyroid carcinoma and clinically suspected bilateral central lymph node enlargement, as well as the postoperative complications, in order to provide comprehensive evidence for doctors to make treatment individually.Methods:We reviewed a prospective protocol of the patients with unilateral differentiated thyroid carcinoma and suspected contralateral central lymph node metastasis by ultrasound or other preoperative examinations from October2005to December2012. All of the patients enrolled in this analysis were first diagnosed and then received bilateral central compartment dissection at Department of Head and Neck Surgery, Fudan University Shanghai Cancer Center. The relationships between lymph node metastasis to contralateral central compartment and clinic-pathologic factors such as gender, age, coexistence of Hashimoto’s thyroiditis, size and number of the primary tumor, perithyroidal invasion and ipsilateral central compartment metastasis were analyzed. These patients accepted clinical follow-up after surgery and the data of postoperative complication, including contemporary and permanent hypoparathyroidism and vocal cord mobility, were recorded.Results:Among the83enrolled patients,69(83.1%) patients had positive central lymph node confirmed by the pathological histopathology and immunohistochemical examination. Of these patients, bilateral central lymph node metastasis was present in50patients (50/83,60.2%), unilateral contralateral central lymph node metastasis in4patients(4/83,4.8%). In the univariate analysis, the rate of contralateral central lymph node metastasis was significantly higher in male patients, carcinoma with a maximal diameter over1cm, histologically proven metastasis to the ipsilateral central lymph node, but the rate was low in patients with coexistence of Hashimoto’s thyroiditis(P<0.05). Multivariate analysis showed that the the presence of ipsilateral central LN metastasis was an independent risk factor for the presence of contralateral central LN metastasis while the presence of coexistence of Hashimoto’s thyroiditis wan an protective factor. ROC curve showed that the metastatic ipsilateral central lymph node ratio was a better diagnostic method of contralateral central lymph node metastasis, and patients with the ratio over44.2%developed a higher possibility of contralateral central lymph node metastasis.82patients accepted clinical follow-up. There were7patients developing lateral neck nodal recurrences and1patient presenting lung metastasis during the follow-up period. Hypocalcemia occurred in14patients(14/82). Among them,1patient (1.2%,1/82) developed permanent hypoparathyroidism.4patients complained contemporary hoarseness with eventual recovery during the six months after surgery.7patients underwent intentional unilateral recurrent laryngeal nerve resection due to direct tumor invasion.Conclusion:Coexisting Hashimoto’s thyroiditis in patients in patients with Unilateral differentiated thyroid carcinoma and suspected bilateral central lymph node metastasis was identified as a negative independent predictive factor for contralateral central lymph node metastasis, while ipsilateral central lymph node metastasis is a potential independent risk factor. These findings suggest that contralateral as well as ipsilateral elective central lymph node dissection, performed during the initial thyroid operation, may be effective in the management of patients with unilateral PTC and suspected bilateral central lymph node metastasis having ipsilateral central lymph node metastasis but without Hashimoto’s thyroiditis coexisting. Furthermore, the metastatic ipsilateral central lymph node ratio is also a reliable diagnostic method for doctors to make decision whether to perform surgery when confronting patients with suspected contralateral central lymph node enlargement during the follow-up period.