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 positives 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.