Molecular staging of the sentinel lymph node in melanoma patients: correlation with clinical outcome

Background: This study was designed to determine the debated prognostic significance of reverse transcriptase–polymerase chain reaction (RT–PCR) positivity in melanoma patients' sentinel lymph node (SLN) negative by conventional histopathology (PATH). Patients and methods: Patients with primary stage I–II cutaneous melanoma underwent radioguided sentinel lymphadenectomy. Their SLNs were assessed for tyrosinase (Tyr) and melanoma antigens recognized by T-cells (MART-1) mRNA expression using RT–PCR, in parallel with hematoxylin and eosin staining and immunohistochemistry. Tyr and MART-1 expression in the SLNs were correlated with PATH assay results, standard prognostic factors, time to progression and overall survival. Results: Twenty-three of the 124 patients (18.5%) had positive SLNs by both PATH and RT–PCR (PATH+/PCR+). Sixteen patients (13%) were negative by PATH and positive by RT–PCR (PATH−/PCR+). Eighty-five patients (68.5%) had SLNs that were negative by both PATH and RT–PCR (PATH−/PCR−). At a median follow-up of 30 months, recurrence rates among the three cohorts were statistically different (PATH+/PCR+, 60%; PATH−/PCR+, 31%; PATH−/PCR−, 9.4%). Seven of 23 (30%) and two of 16 (12.5%) patients died in the PATH+/PCR+ and PATH−/PCR+ SLN groups, respectively, whereas no patient died in the PATH−/PCR− SLN group. Conclusions: RT–PCR is more sensitive than PATH to detect SLN metastases and it is a reliable predictor of disease relapse in stage I–II melanoma patients