HEMATOGENOUS SPREAD OF MALIGNANT-MELANOMA CELLS IN DIFFERENT STAGES OF DISEASE

Patients with malignant melanoma and distant metastases generally have an unfavorable prognosis, with a median survival of about 6 months. T he mechanisms of hematogenous spread and implantation of melanoma cell s are, however, poorly understood, because the standard diagnostic met hods are not sensitive enough to detect oligocellular micrometastases. Recently a method using reverse transcription and polymerase chain re action to determine tyrosinase mRNA in peripheral blood, which indicat es the presence of circulating melanoma cells, has been developed. We utilized this assay to examine blood samples of 56 patients with malig nant melanoma in different stages of disease. In one of 10 patients in stage I (localized disease) and in six of 17 patients with regional l ymph nodes metastases (stage II) tyrosinase mRNA was detected. Tyrosin ase transcripts were found in all 29 patients with distant metastases (stage III). Interestingly, tyrosinase mRNA was also detected in six p atients with metastatic amelanotic malignant melanoma. In contrast, ty rosinase mRNA was not detectable in any of 39 healthy subjects or 17 p atients with other malignancies. These findings may be helpful to defi ne a patient group at high risk for systemic spread of disease.