Sentinel node localization in primary melanoma: learning curve and results

Ninety primary melanoma patients were studied to investigate the importance of adopting the simultaneous use of patent blue dye (PBD) and lymphoscinti graphy plus gamma detection probe to locate the sentinel node (SN). In tota l 135 SNs in 105 basins were visualized preoperatively under a gamma camera after lymphoscintigraphy. When a SN was identified intraoperatively, its r adioactivity level and colour were verified and documented. Two of the SNs seen on lymphoscintigraphy were not found. Using PBD 78.52% of the SNs were identified; 95.5% were identified using the gamma detection probe. Using b oth methods together 98.5% of the SNs were detected. Twenty-two patients (2 4.4%) had pathologically positive SNs. The surgical learning curve was asse ssed for the two techniques. The learning curve associated with the methodo logy was important in finding the SN when using PBD associated with lymphos cintigraphy, but not when the gamma detection probe was used; we found a st atistically significant reduction in the percentage of stained SNs found us ing pan in the initial 14 SNs biopsied compared with the subsequent 121 nod es. This is important as not all institutions have access to a gamma probe. The time required to identify each SN was documented and analysed. The dur ation of the procedure was significantly shorter for stained SNs than for n on-stained SNs, which support the use of both PBD and the gamma probe. In c onclusion, SN biopsy should be performed by surgeons and nuclear medicine d octors in co-operation, both methods being adopted simultaneously to reduce the percentage of procedure failures, (C) 1999 Lippincott Williams & Wilki ns.