Sentinel Lymph Node Biopsy in Cutaneous Melanoma

Abstract

Melanoma is an important public health problem, and its incidence is increasing worldwide. The disease status of regional lymph nodes is the most important prognostic factor in early-stage melanoma patients. Sentinel lymph node biopsy (SLNB) was introduced in the early 1990s as a less invasive procedure than complete lymph node dissection to allow histopathologic evaluation of the "sentinel lymph node" (SLN), which is the first node along the lymphatic pathway from a primary tumor. Sentinel lymph node biopsy has minimal complication risks compared with standard complete lymph node dissection. Currently, SLNB is the accepted method for staging patients with clinically node-negative cutaneous melanoma and provides the most powerful prognostic information by evaluating the nodal basin status. The current practice of SLNB consists of the injection of Tc-labeled radiopharmaceutical, preoperative lymphoscintigraphy with the possibility of using the SPECT/CT hybrid imaging, and intraoperative SLN localization using a handheld gamma probe with or without the use of blue dye. Recently, the SLN localization and detection have been enhanced with the use of new tracers and new intraoperative devices, which have demonstrated to be particularly useful in melanomas of the head and neck region and in area of complex anatomy. Despite these important advances in the technology and the increasing experience in SLN mapping, major research centers have reported a false-negative rate higher than 15%. This relatively high false-negative rate, greater than those reported in the initial validation studies, points out the importance for the nuclear medicine community to continuously improve their knowledge on the biological behavior of melanoma and to improve the technical aspects that may allow more precise staging. For the SLNB procedure to be accurate, it is of critical importance that all "true" SLNs are identified and removed for examination. The aim of this article is to provide general information about the SLNB procedure in clinical practice highlighting the importance of standardization and accuracy of SLN identification in the light of the most recent technical innovations.

Comparison of 99mTc-Labeled Colloid SPECT/CT and Planar Lymphoscintigraphy in Sentinel Lymph Node Detection in Patients with Melanoma: A Meta-Analysis

“…A higher DR and the larger number of SLNs identified by the SPECT/CT on a head-to-head comparison with PL can theoretically also determine a meaningful impact in surgical decision making. Nevertheless, the preoperative use of SPECT/CT for the identification of SLNs is not only important for the additional number of SLNs but also for the capability of providing anatomical information [21,53]. Furthermore, SPECT/CT may also localize unspecific hot spots that could be mistaken as additional SLNs using only PL [54].…”

“…SPECT/CT seems to provide a meaningful impact on surgery, possibly influencing the patient outcome [53]. The large prospective multicenter International Atomic Energy Agency Sentinel Node Trial demonstrated that SPECT/CT had modified the surgical approach in 97 patients with melanoma (37% of the patient population): 41.6%, 39.7%, 33.3% and 30.2% of subjects with head and neck, trunk, lower limb and upper limb lesions, respectively [34].…”

Sentinel Node Identification in Melanoma: Current Clinical Impact, New Emerging SPECT Radiotracers and Technological Advancements. An Update of the Last Decade

“…The removal of the SLN avoids the side effects of complete lymph node dissection (CLND); furthermore, prospective trials demonstrated no improvement in survival for patients with melanoma undergoing CLND [ 6 , 7 ]. CLND should, therefore, be preferentially suggested for patients with positive SLN [ 8 ].…”

Sentinel lymph node mapping using ICG fluorescence and cone beam CT – a feasibility study in a rabbit model of oral cancer

“…Sentinel lymph node biopsy (SLNB) is a well-established technique used in many subsites of oncology, including breast cancer, skin cancer and melanoma. In these settings, SLNB has been shown to be sensitive, specific, reduce morbidity and demonstrates survival rates at least as good as with more comprehensive lymph node dissection [ 4 , 5 ]. The most recent National Comprehensive Cancer Network (NCCN) clinical practice guidelines for head and neck oncology and National Institute for Clinical Excellence (NICE) guidelines addresses the clinical dilemma of the N0 neck in early stage (T1/T2) oral cancer, stating that sentinel lymph node biopsy is an alternative to elective neck dissection for identifying occult cervical metastasis [ 6 ].…”