Abstract: Background and purpose: For treatment of papillary thyroid carcinoma (PTC), there is substantial divergence of opinion in neck dissection currently. In this study, we aimed to provide theoretical basis for selective neck dissection through summarizing the characteristics of cervical lymph node metastasis (LNM) in PTC. Methods: From Jul. 2006 to Aug. 2014, 462 patients with PTC at our hospital were retrospectively analyzed. We analyzed the characteristics and predictive factors of cervical LNM and evaluated the accuracy of cN₀ standard. Results: All patients received ipsilateral central cervical lymph node dissection (Level Ⅵ). 320 patients underwent lateral cervical lymph node dissection (Level Ⅱ-Ⅴ) or elective lymph node dissection (some or all of Level Ⅱ-Ⅳ). 90 patients received contralateral central cervical lymph node biopsy. 73.2% (338/462) were cN0 patients, but among those 184 patients were pathologically confirmed with LNM. The misdiagnosis rate of cN₀ standards was 60.9%. The cervical LNM rate was 65.4% (302/462) in total. The lateral compartment LNM rate was 42.6% (197/462). 13.1% (42/320) patients had skip lateral cervical LNM leaping central compartment, whereas 50% (45/90) with contralateral level Ⅵ metastasis. Male, tumor involving upper 1/3 gland, tumors T₃ or T₄, and multicentricity were all predictive factors of LNM. Patients with tumor involving upper 1/3 gland prone to prelaryngeal lymph node (PLN) metastasis and “skip metastasis”. Lateral compartment LNM increased significantly when PLN(+) and ≥2 central lymph nodes metastasis (85.7% and 83.3%, respectively, P<0.05). Conclusion: Existing cN₀ standard is not a suitable criteria for determining the margin of lymph node dissection. PTC is prone to lymph node metastasis, and level Ⅵ is most likely to be involved, then Ⅲ, Ⅱ, Ⅳ, Ⅴ. Ipsilateral central lymph nodes should be routinely dissected and intraoperative frozen examination is suggested in initial surgery. If patients had PLN metastasis, or ≥2 central lymph nodes metastasis, or tumor involving upper 1/3 gland, lateral cervical lymph node dissection (or elective lymph node dissection) is necessary. Attention should be paid to contralateral level Ⅵ for it has high metastasis rate. Subdivision of central compartment is of great significance and needs thorough research.

Key words: PTC, Lymph node metastases, cN₀, Intraoperative frozen, Prelaryngeal lymph node