Impact of Molecular Staging Methods in Primary Melanoma: Reverse-Transcriptase Polymerase Chain Reaction (RT-PCR) of Ultrasound-Guided Aspirate of the Sentinel Node Does Not Improve Diagnostic Accuracy, But RT-PCR of Peripheral Blood Does Predict Survival

Abstract

This study analyzes (1) the value of tyrosinase reverse-transcriptase polymerase chain reaction (RT-PCR) of aspirates obtained by ultrasound-guided fine-needle aspiration cytology (US-FNAC) of sentinel nodes (SNs) in patients with melanoma before sentinel lymph node biopsy (SLNB) and (2) the value of RT-PCR of blood samples of all SLNB patients. Between 2001 and 2003, 127 patients with melanoma (median Breslow depth, 2.1 mm) underwent SLNB. FNAC was performed in all SNs of all patients pre- and post-SLNB. The aspirates were partly shock-frozen for RT-PCR and were partly used for standard cytology. Peripheral blood was collected at the time of SLNB and at every outpatient visit thereafter. Thirty-four (23%) of 120 SNs were positive for melanoma. SN involvement was predicted by US-FNAC with a sensitivity of 82% and a specificity of 72%. Additional tyrosinase RT-PCR revealed the same sensitivity of 82% and a specificity of 72%. At a median follow-up time of 40 months from first blood sample, peripheral-blood RT-PCR was a significant independent predictor of disease-free survival (DFS) and overall survival (OS; P < .001). US-FNAC is highly accurate and eliminates the need for SLNB in 16% of all SLNB patients. RT-PCR of the aspirate or excised SN does not improve sensitivity or specificity. RT-PCR of blood samples predicts DFS and OS.