Sentinel node sampling(SLND) is a technique most commonly used for staging breast cancer and melanoma. A dye, or more recently radionucleide is injectde into the tumor bed and is traced to the lymph node or nodes that predominantly drain that area. This node(s) is then sampled, avoiding extensive nodal dissection.
Patients with melanomas less than or equal to 1.0 mm in thickness are at lower risk for nodal involvement (2-5%), and there is debate as to whether they would benefit from evaluation of their nodal basin. Currently, the National Comprehensive Cancer Network (NCCN) recommends against SLND for patients with melanoma in situ or melanoma less than 1.0 mm in thickness. Patients with melanoma between 0.76 mm and 1.0 mm in thickness may be considered for SLND if they have adverse features such as positive deep margins, lymphovascular invasion, age less than 40 years, significant vertical growth face, increased mitotic rate, and Clark’s level IV or higher. Those with melanoma that exhibits regression may also be considered, but this is more controversial. Some recent studies have indicated that there may be no association between regression and positive SLN status. SLND is also offered to patients with deep (>4 mm) melanoma and clinically negative nodes because it has proven to yield valuable prognostic information, with rates of positive SLNs ranging from 30-40%.
Similarly, ASCO 2012 recommends: ” SLN biopsy is recommended for patients with intermediate-thickness melanomas (1-4mm Breslow thickness) of any anatomic site; use of SLN biopsy in this population provides accurate staging. While there are few studies focusing on patients with thick melanomas (T4; >4mm Breslow thickness), SLN biopsy may be recommended for staging purposes and to facilitate regional disease control. There is insufficient evidence to support routine SLN biopsy for patients with thin melanomas (T1; <1mm Breslow thickness), although it may be considered in selected cases with high risk features when staging benefits outweigh risks of the procedure. Completion lymph node dissection (CLND) is recommended for all patients with a positive SLN biopsy and achieves good regional disease control. Whether CLND following a positive SLN biopsy improves survival is the subject of the ongoing Multicenter Selective Lymphadenectomy Trial II.”
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