The predictors of “hidden” central neck lymph node metastasis in patients with differentiated thyroid cancer

Background. The regional lymph node metastasis in differentiated thyroid cancer (DTC) is still very high: 50–60%, especially in papillary form. Averagely, after central neck lymph node dissection (CNLD), in 30–40% cases “hidden” metastasis in lymph nodes of VI zone of neck were revealed. But they were not indicated by preoperative diagnostic procedures: ultrasound (US) and computer tomogpraphy (CT). Aims. To define the factors associated with the increased risk of lymph node metastasis for specification of indications to CNLD performance. Materials and methods. The study covers 105 patients with clinical stages of DTC T1-2N0M0, who received a thyroidectomy (TE) with preventive bilateral CNLD in RSCRR since 2012 till 2017. Patients older than 45 y.o. prevailed (66 patients (62.9%)). Data processing was carried out in a Microsoft Access database, a one-factor dispersion analysis was used for the analysis of the quantitative signs, and a c-square criterion was used for the qualitative ones. Results. The “hidden” metastasizes are founded by 32 (30.5%) patients. Multifocality is registered in 29 (27.6%) cases, lack of the tumor node capsule is registered in 65 (61.9%) and an invasion of the thyroid gland capsule is registered in 38 (36.2%) patients. Background diseases of the thyroid gland (TG) have 69 (65.7%) patients. According to the multifactorial analysis reliable independent predictors of the “hidden” metastasis of central neck lymph nodes were invasion of the anatomic capsule of TG (р = 0.003), age of patients ≤45 y.o. (р = 0.005), nonincapsulated form of tumor (р = 0.007). Conclusion. Use of TE in combination with CNLD allowed to restage at 46.7% of patients due to TG capsule invasion (28.6%) and “hidden” metastasis in VI group lymph nodes (30.5%) identification.