Sentinel node biopsy in melanoma delays recurrence but does not change melanoma-related survival: a retrospective analysis of 673 patients

BACKGROUND: The status of the sentinel lymph node (SLN) is an important parameter to predict the prognosis of melanoma patients but it is a matter of debate if removal of micrometastases by SLN biopsy (SLNB) influences the prognosis of melanoma patients. OBJECTIVES: We sought to investigate the impact of SLNB in melanoma patients with regard to recurrence-free survival, overall survival and metastatic pathways. PATIENTS AND METHODS: We studied, retrospectively, 673 melanoma patients with a primary melanoma (tumour thickness > or = 1 mm) and without clinical evidence of metastases at the time of melanoma diagnosis. In 377 patients the melanoma was removed without SLNB between January 1995 and March 2000 (pre-SLNB group). In 296 patients the melanoma was removed with SLNB between April 2000 and March 2003 (SLNB group). Otherwise, both groups received identical surgical treatment of the primary melanoma and initial staging procedures performed by the same team of physicians. Follow-up recommendations were also identical in both groups. RESULTS: Both groups showed no significant differences with regard to characteristics of the primary melanoma, sex and age. By Kaplan-Meier analyses, melanoma-related overall survival was comparable in both groups. However, recurrence-free survival was increased in pre-SLNB patients due to significantly fewer regional lymph node metastases, whereas frequencies of locoregional cutaneous and distant metastases were comparable in both groups. CONCLUSIONS: SLNB advances the detection of regional lymph node metastases and therefore avoids nodal recurrences but does not influence metastatic behaviour of melanoma cells and does not protect patients from melanoma-related death caused by distant metastases. Thus, our retrospective data favour the marker hypothesis for melanoma metastasation. To elucidate further if subgroups of patients benefit from SLNB, prospective randomized studies with long-term follow-up are needed.