Prognostic role of sentinel node biopsy in patients with thick melanoma: a meta-analysis

Objectives Sentinel lymph node (SLN) biopsy is a prognostic tool for patients with intermediate-thickness melanomas. However, controversies exist regarding its role in patients with thick melanomas (tumour thickness greater than 4.0 mm). We performed a meta-analysis to assess the prognostic role of SLN in thick melanoma in terms of disease-free survival (DFS) and overall survival (OS). Methods An electronic search in MEDLINE and EMBASE databases using the terms 'melanoma' and 'sentinel lymph node' was performed. Studies were considered if they reported data on thick melanoma and SLN biopsy results (positive and negative) and outcomes (DFS or OS). A proportion meta-analysis was used to calculate weighted means and an incidence rate ratio meta-analysis was used to compare outcomes according to SLN biopsy results. Results Nine studies were included. The weighted mean thickness of melanoma was 4.4 mm, 42% of patients had ulcerated melanoma. SLN was positive in 36% of the patients. Overall, DFS was 71% in patients with a negative SLN and 39% in patients with a positive SLN after a median follow-up of 33 months (IRR 1.83, 95% CI = 1.56-2.14). OS was 71% in patients with a negative SLN and 49% in patients with a positive SLN (IRR 1.44, 95% CI = 1.25-1.65). Conclusions The results of this analysis showed that thick melanoma patients with a positive SLN had a significantly worse survival compared with SLN negative patients, thus supporting the routine adoption of SLN biopsy as a prognostic tool also for this subgroup of patients.