Sentinel node biopsy for malignant melanoma: Analysis of a four-year experience

Aims and background: Sentinel node (SN) biopsy has been introduced to solve the controversy concerning the effectiveness of prophylactic lymphadenecto my in intermediate thickness melanoma. The aim of this study was to evaluat e the rate of metastases, the technical details of the procedure, and the m ain reasons of failure. Methods: 235 patients affected by intermediate thickness melanoma (tumor th ickness >0.75 mm and <4 mm) without clinical signs of systemic spread (N0M0 ) were submitted to sentinel node biopsy between 1996 and 2000. Preoperativ e lymphoscintigraphy was routinely performed in the last 184 patients. Intr aoperative mapping with gamma probe was combined with the use of vital dye for identification of sentinel nodes in the last 113 patients. Results: The SN detection rate was 95.6%, with significant differences depe nding on the site of dissection and the use of a gamma probe. The overall r ate of micrometastases was 14.7%, but relevant differences were recorded be tween different subgroups of patients (T-2, 5.1%; T-3a, 19 6%; T-3b, 29%). Conclusions: Sentinel node biopsy requires a multidisciplinary approach (su rgery, pathology and nuclear medicine) for reliable results. The associatio n of vital dye and intraoperative gamma probe for sentinel node harvesting has made the procedure more effective, less time-consuming and less invasiv e. Failures may be due not only to surgical mistakes, but also to improper nuclear medicine procedures or inaccurate histological evaluation of SNs, M ethods for histological examination of the SN are still debated and not sta ndardized but promising results have recently been obtained with molecular oncology techniques (RT-PCR).