Lateral cervical lymph node metastases from papillary thyroid carcinoma: predictive factors of nodal metastasis.

BACKGROUND Papillary thyroid carcinoma (PTC) frequently metastasizes to the regional neck; skip metastasis (metastasis to the lateral compartment in the absence of central disease) is uncommon. This prospective study was to evaluate the incidence of occult lateral neck metastasis (LNM) and elucidated the factors that predict LNM in PTC with central neck metastasis (CNM) by performing prophylactic selective lateral neck dissection (SND). METHODS Sixty-two patients with PTC without clinical LNM underwent total thyroidectomy with central compartment neck dissection and prophylactic SND consecutively after ipsilateral CNM was confirmed by intraoperative frozen biopsy. RESULTS The incidence of occult LNM in PTC was 55%. Patients with LNM had a larger primary tumor and more positive ipsilateral and bilateral central lymph nodes than patients without LNM. There were no differences between patients with and without LNM with regard to age and extrathyroidal extension. The incidence of occult LNM increased significantly as the number of metastatic ipsilateral and bilateral lymph nodes increased. Independent risk factors for occult LNM were tumor size and the number of positive bilateral lymph nodes (odds ratio [OR] = 1.449; OR = 1.110, respectively). The most common metastatic site was level III (68%: 23/34), followed by level IV (59%: 20/34) and level II (21%: 7/34). CONCLUSION The important risk factors for LNM in PTC are primary tumor size and the number of positive bilateral central lymph nodes. Prophylactic SND may be considered in selected patients with a large number of positive central lymph nodes and large tumors.