Clinicopathological utility of molecular staging for melanoma patients undergoing sentinel lymphadenectomy.

Lymphatic mapping and sentinel lymph node (SLN) biopsy have been validated in malignant melanoma. We hypothesized that histopathologically negative SLNs may contain occult metastases that can be identified by sensitive molecular approaches such as quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) assay. We previously demonstrated that RT-PCR-based detection of occult metastasis in frozen SLNs upstaged early-stage cutaneous melanomas and that a multiple specific mRNA marker (MM) RT-PCR assay was an independent predictor of disease outcome. We recently developed an MM RT-PCR using electrochemiluminescence (ECL) and quantitative real-time detection assays. These assays can detect occult metastatic melanoma cells in paraffin-embedded (PE) SLNs and are of clinical utility for retrospective analysis of specimens with long-term follow-up. The molecular detection of occult metastasis in PE SLNs has significant clinicopathologic and logistic advantages over molecular analysis of frozen SLNs.