Aim: Occult lymph node metastasis is common in differentiated thyroid cancer (DTC). However, the role of lymph node dissection in the treatment of DTC remains controversial. The authors investigated the usefulness of methylene blue dye only method and combined radioisotope and methylene blue dye method for detecting SLN and compared the values of these two methods in patients with DTC.
Methods: From February to May 2008, 97 patients with DTC underwent sentinel lymph node biopsy (SLNB). The methylene blue dye method (dye only method) was used in 54 of the 97 patients, and radioisotope and methylene blue dye method (combined method) in 43 patients.
Results: The SLNs were identified in 89 patients, and the sensitivity and specificity of SLNB in the 97 patients were 85% and 100% respectively. For the dye only method, sensitivity, specificity, and the false negative rate (FNR) were 79%, 100%, and 21%; and for the combined method (43 patients) the corresponding figures were, 91%, 100%, and 9%, respectively. Six patients with SLN metastasis in the lateral neck underwent additional modified radical neck dissection (MRND).
Conclusions: SLNB was found to be feasible, repeatable, and accurate in evaluating the lymph node status in patient with DTC. The present study indicates that the combined method could reduce false negative rate and increase detection rates of sentinel lymph node metastases, especially in lateral neck, compared to the dye only method.