MOLECULAR TEST FOR THE DETECTION OF TUMOR-CELLS IN BLOOD AND SENTINELNODES OF MELANOMA PATIENTS

Lymph node metastasis dramatically decreases the 5-year survival of me lanoma patients, The so-called sentinel none surgery offers a therapeu tic approach to resect the first draining lymph node. This technique e nables accurate staging of melanoma patients in an early stage of the disease Detection of a sentinel none metastasis is a strong argument f or local lymphadenectomy. To improve the detection of micrometastasis in sentinel nodes of melanoma patients, molecular biological technique s were used. The exclusively melanocyte-specific tyrosinase transcript was amplified by reverse transcription followed by polymerase chain r eaction (RT-PCR). In sentinel node examination, the detection of tyros inase-positive cells by RT-PCR tuns compared with routine immunohistoc hemistry. From 16 patients, a total of 28 lymph nodes were tested. The lymph nones were derived after lymphadenectomy (4 patients) and after sentinel node resection (12 patients with melanoma stage I). By using RT-PCR we could detect 100 tumor cells in a background of 10(8) perip heral blood mononuclear cells. The negative controls were all negative for tyrosinase. Cryostat sections of lymph nodes for mRNA isolation w ere alternated with sections for immunohistochemistry. By using tyrosi nase RT-PCR, we detected 6 additional positive sentinel nodes in patie nts with melanoma stage I. Furthermore, the tyrosinase RT-PCR enabled us to design a blood test for circulating melanoma cells. Therefore, m RNA was directly isolated from whole blood of 23 blood samples, of whi ch 3 samples were positive for tyrosinase. The present study demonstra tes the possibility of a simple and rapid blood test for melanoma pati ents that has not been available until now. Furthermore, the detection of micrometastasis in sentinel nones by tyrosinase RT-PCR dramaticall y increases the accuracy of melanoma staging.