1. ^*Institute of Immunology, University of Heidelberg, Heidelberg, Germany
2. ^†Department of Dermatology, University of Heidelberg, Heidelberg, Germany
3. ^‡Institute of Medical Biometry and Informatics, University of Heidelberg, Heidelberg, Germany

Correspondence: Thomas Giese MD, Institute of Immunology, Im Neuenheimer Feld 305, D-69120 Heidelberg, Germany. Email: Thomas.Giese@urz.uni-heidelberg.de

Received 4 August 2004; Revised 13 October 2004; Accepted 9 November 2004.

Abstract

Detection of micrometastases in the regional tumor-draining lymph nodes is critical for staging and prognosis in melanoma patients. We applied a quantitative multiple-marker RT-PCR assay to improve the detection of occult melanoma cells in the sentinel lymph node (SLN). From 139 patients with primary cutaneous melanoma who underwent sentinel lymphadenectomy, a total of 235 SLN were assessed for Melan-A and tyrosinase expression by real-time quantitative RT-PCR. Twenty-three patients (17%) were positive by histopathology and expressed messenger RNA of one or two markers. Of the patients with histopathologically negative SLN 39 (28%) were reclassified by positive RT-PCR. Patients were examined for tumor recurrences during a median follow-up period of 29 mo. Tumor recurrences were demonstrated in eight patients (35%) with histopathologically positive SLN, in four patients (10%) with submicroscopic tumor cells detected exclusively by real-time RT-PCR, and in none of the patients negative by both methods. The differences in recurrence rates were statistically significant (p=0.01). These data indicate that real-time quantitative RT-PCR for the detection of minimal residual melanoma in SLN improves the prediction of disease-free survival.