Sentinel Lymph Node Biopsy in Thyroid Cancer

Abstract

The role of sentinel lymph node biopsy (SLNB) in thyroid cancer is still debatable. The primary goals of SLNB are to facilitate accurate identification of lymph node (LN) metastasis without formal lymphadenoectomy to reduce morbidity associated with LN dissection. SLN in thyroid cancer can be identified using either vital blue dye, radioactive tracer, or a combination of these methods. Here, 26 selected studies of SLNB for thyroid cancer are analyzed and reviewed. For the vital blue dye, radioisotope, and combined methods, the overall sentinel node identification rates (SNIRs) were 84.0, 98.4 and 97.9%, the overall sensitivities were 86.1, 66.7 and 90.7% and the overall false negative rates were 11.4, 16.3, and 11.4%, respectively. The combined blue dye and radioisotope method had superior SNIRs, sensitivities, and false negative rates than the single vital blue dye technique. New tracers such as carbon nanoparticles can be used in SLNB. Lateral compartment SLNB studies employing a radioisotope technique can be useful for evaluation of the occult lateral neck LN status in patients with papillary thyroid cancer (PTC), especially in cases of central neck node metastasis. Lateral SLNB may also provide useful information for medullary thyroid cancer (MTC) treatment.

Sentinel lymph node biopsy in medullary thyroid microcarcinomas

“…In our study, two patients with LN metastases had basal CT levels of 221.6 and 42.0 pg/mL, while those with higher values, over 500 pg/mL, for example, were staged pN0. Physical examination and US evaluation are used to guide the extent of LN surgery, but are not always reliable [1,15]. Intraoperative assessment of LNs by a surgeon was also shown not to be accurate enough, with sensitivity of 64% [36].…”

“…General recommendation for treatment of MTC is TT with prophylactic CLND, even in patients with micro-MTCs [1,2,[13][14][15][16][17][18], and this surgical strategy is used in Many studies upon clinical behavior of MTCs acknowledged that LN metastases occur early in the course of MTC, regardless the tumor size [2,37]. For example, at the time of diagnosis, over 70% of patients with palpable MTC [36] and over 35% of micro-MTCs [9] have LN metastases.…”

“…There are various tracers available for LN mapping, like: vital blue dyes (MBD, IBD and Patent Blue V dye), fluorescent dyes (indocyanine green), radionuclide (Tc99m-labeled radiocolloid), Carbon nanoparticles or magnetic particles [15]. Majority of tracers require some additional equipment for imaging, like: (a) gamma camera and hand-held gamma probe or single-photon emission computed tomography for radionuclide tracers [40], (b) SPY Elite system and Hamamatsu PDE-Neo probe for indocyanine green fluorescence [41], or (c) magnetic particle imaging scanner and handheld magnetic probe if magnetic particles are used [42].…”

“…False negative findings on preoperative physical examination and ultrasonography of regional LNs can lead to initial undertreatment of patients with this disease. Due to permanent concerns regarding under-and over-treatment of patients, surgical recommendations for MTC management are not unanimous, but majority of those agree upon necessity of total thyroidectomy (TT) with prophylactic central lymph node dissection (CLND) [1,2,[13][14][15][16][17][18]. The necessity of lateral lymph node dissections (LLND) in clinically evident disease is indisputable; however, its extent in clinically N0 patients is a matter of debate, ranging in the literature from (a) bilateral prophylactic LLND [10,12,16,19], as the most radical approach; or (b) sampling of lateral LNs, as less radical strategy to determine the necessity of complete LLND in histologically proven metastatic disease [20]; to (c) performing ipsilateral LLND only in case of positive central LNs [1,[21][22][23].…”

Role of Sentinel Lymph Node Biopsy in Papillary Thyroid Carcinoma in Vietnam

“…[19][20] Benefits of SLN biopsy in breast cancer are clear: it lets to reduce the need for axillary lymph node dissection, which can cause edema of arms. 21 However, SLN biopsy application to the treatment of PTC patients still has not been thoroughly investigated. This research will provide the feasible, predictive values in metastasis of SLN biopsy among Vietnamese patients with PTC.…”