New developments in sentinel node staging in melanoma: Controversies and alternatives

PURPOSE OF REVIEW: Melanoma incidence is increasing worldwide. Elective lymph node dissections (ELNDs) could not improve survival. The sentinel node is a targeted approach to occult lymph node metastases. There are controversies regarding the sentinel node procedure for melanoma, with regard to false-negative rates, therapeutic benefit and alternatives, such as ultrasound. The clinical relevance of minimal sentinel node tumor burden is unclear. This review analyzes these issues. RECENT FINDINGS: Through the pathological work-up of the sentinel node, the sentinel node has become an independent prognostic factor for survival in melanoma. False-negative rates of the sentinel node procedure are generally an underestimation, due to incorrect calculations. A subgroup analysis of the Multicenter Selective Lymphadenectomy Trial (MSLT)-1 seemed to demonstrate a survival benefit, but is criticized for a number of reasons. Potentially, a subgroup of sentinel node-positive patients is prognostically false-positive, with dormant metastases, which might not become viable disease. SUMMARY: Sentinel node tumor burden is an extra dimension to predict prognosis, although we have not yet identified the correct group to undergo a completion lymph node dissection. The MSLT-2 and MINITUB studies are analyzing this issue. The EORTC recommends the Rotterdam criteria as the most reproducible and accurate measure of sentinel node tumor burden. Ultrasound-guided fine needle aspiration cytology is emerging as a potential cost-effective alternative.