Clinical significance of sentinel lymph node involvement in malignant melanoma

In the period 1997-2002, sentinel lymph node (SLN) surgery was performed on 179 primary skin melanoma patients, one to two months after the removal of the primary. Staining with patent blue was combined with an isotope technique. Histological evaluation of the sentinel lymph nodes was performed in serial sections. Immunohistochemical detection of S100, HMB-45, or Melan-A was used in the case of suspected micrometastases. Demonstration of positive sentinel lymph node was followed, preferably within 2-3 weeks, by regional block dissection. In these cases interferon-a2 in low doses or BCG immune therapy were applied as adjuvant therapy. Bimonthly follow-up of the patients included physical examination and the use of imaging techniques as specified in the melanoma protocol. Sentinel lymph node surgery was successful in 177/179 cases (98%). Positive sentinel lymph node was identified in 26/177 patients (14.7%). In node positive patients the thickness of the primary tumour was significantly greater than that of node negative ones (p<0.00001). Patients with micrometastases had significantly poorer symptom-free and overall survival by the Mantel-Cox test than those of the other group (p=0.0001 and p=0.0007 respectively). Comparison of the tumor thickness and positive SLN by discriminance analysis, yielded 81.7% and 79.9%, respectively for correct classification rates. Based on our study and data from the literature, we suggest SLN-positivity as equally strong poor prognosis factor for skin melanoma as the tumor thickness.