Background: Sentinel lymph node biopsy (SLNB) is a minimally invasive procedure used accurately to stage nodal basins at risk of occult metastases. There are no data as yet to show a survival benefit from SLNB and its use remains controversial. If Breslow thickness of the tumour correlates well with positive SLNB, it could be used to select patients for SLNB.
Methods: A quantitative systematic review of published studies on SLNB in patients with melanoma available by September 2001 was performed.
Results: Twelve studies containing 4218 patients with stage I and II melanoma were identified; 17.8 (95 per cent confidence interval 16.7 to 19.0) per cent of patients had nodal micrometastases detected by SLNB. The incidence of micrometastasis in sentinel nodes correlated directly with Breslow tumour thickness; it was 1.0 per cent for lesions of less than or equal to 0.75 mm, 8.3 per cent for 0.76-1.50 mm, 22.7 per cent for 1.51-4.0 mm and 35.5 per cent for more than 4.0 mm.
Conclusion: The Breslow thickness of primary melanoma predicts the presence of a sentinel node metastasis. The published data are not sufficient to demonstrate a correlation between other known prognostic indicators and a positive SLNB.