Radioguided sentinel lymph node biopsy in patients with papillary thyroid carcinoma

Background: The ATA guidelines do not recommend prophylactic central compartment neck dissection in patients with T1-T2 papillary thyroid carcinoma (PTC) with no clinical evidence of lymph node metastasis, however patients' staging is recommended. Lymph node metastasis may be present also in small PTC, but preoperative ultrasound identifies suspicious cervical lymphadenopathy in 20-30% of patients. The role of sentinel lymph node biopsy (SLNB) remain open to debate. It has been shown that the identification rate of SLN in PTC patients is improved using a radiotracer compared to a dye technique. The aim of this systematic review was to evaluate the role of radioguided SLNB (rSLNB) in the treatment of PTC patients. Methods: A systematic search was performed in the PubMed and Embase database to identify all original articles regarding the application of rSLNB in PTC patients. The primary outcome was false negative rate (FNR) of the rSLNB; the secondary outcomes were SLN intraoperative identification rate (IIR), site of lymph node metastasis, and persistent disease during follow up. Results: Twelve studies were included. Most of PTC patients were T1-T2. The overall SLN IIR, SLN metastatic rate, and FNR were 92.1%, 33.6%, and 25.4%, respectively. Overall, lymph node metastasis were found in the central compartment (23.0%) and in the lateral compartments (10.6%). The persistent disease in patients who underwent SLNB associated to lymph node dissection (LND) in the same compartment of the SLN regardless of the SLN status was 0.6%. Conclusions: In all PTC patients, also in T1-T2 stage, due to the high FNR the SLNB performed alone should be abandoned and converted into a technique to guide the lymphadenectomy in a specific neck compartment (i.e., central or lateral) based on the radioactivity, regardless of the SLN status, for better lymph node staging and selection of patients for postoperative radioiodine ablation.