Characteristics of node metastases for clinically node-negative patients with papillary thyroid carcinoma

OBJECTIVE: To determine the characteristics of cervical lymph node metastases for clinically node-negative patients with papillary thyroid cancer and explore treatment for affected lymph nodes.MESTHODS: Retrospective chart review of 107 clinically node-negative thyroid papillary carcinoma patients was performed.According to the size of tumor and treatment to the lymph node,patients were divided into 3 groups.Group A: tumor diameter ≤ 1 cm and lymph node dissection in ipsilateral level Ⅵ;Group B: tumor diameter 1-3 cm and bilateral lymph node dissection in level Ⅵ with level ipsilateral Ⅲ,Ⅳlymph nodes removed for pathology examination;Group C: tumor diameter 3 cm and bilateral lymph node dissection in level Ⅵ with level ipsilateral Ⅲ,Ⅳlymph nodes removed for pathology examination.Metastasized cases underwent modified neck dissection.RESULTS: The rates of metastasis to the ipsilateral level Ⅵ were 41.1%,61.1% and 73.3% for A,B,C groups respectively.The difference in the three groups was statistically significant(χ2=6.610 9,P=0.036 7).The rates of metastasis to the contralateral level Ⅵ were 30.5% and 73.3% in group B and group C.The difference was statistically significant(χ2=3.851 0,P=0.049 7).The rates of metastasis to the level Ⅲ,Ⅳ in group B and group C were 19.4% and 46.7% respectively.The difference was statistically significant(χ2=4.267 4,P=0.038 9).CONLUSIONS: Patients with clinically node-negative papillary thyroid cancer are prone to lymph node metastasis at level Ⅲ,Ⅳ and Ⅵ.Patients with tumor diameter ≤1 cm should undergo an anipsilateral level Ⅵ dissection.Patients with tumor diameter 1 cm should undergo both bilateral level Ⅵ dissection and an ipsilateral level Ⅲ-Ⅳ lymph nodes frozen pathology examination.Level Ⅲ-Ⅳ metastasized cases should undergo modified neck dissection.