Tumour thickness as a predictor of occult lymph node metastases in patients with stage I and II melanoma undergoing sentinel lymph node biopsy

Abstract

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.