Clinical significance of the molecular detection of melanoma cells circulating in the peripheral blood in melanoma patients

Background. Blood circulating melanoma cells may be important for the sprea d of the disease. The current methods are not sensitive in detecting micro metastases. Tyrosinase mRNA can be detected in peripheral blood by a molecu lar test. As tyrosinase is expressed only in melanocytes and melanocytes no rmally do not circulate in the blood, the test may prove reliable in detect ing circulating melanoma cells. Methods. Experimental design: we used a reverse-transcription polymerase ch ain reaction (RT-PCR) detecting tyrosinase mRNA in the blood. A prospective investigation in melanoma patients undergoing surgery was conducted; follo w-up duration was 12 months. Setting: University Department Laboratory and Melanoma Clinic of a Tertiary Hospital. Patients: a total of 27 Greek patie nts with a diagnosis of malignant melanoma at different stages of the disea se; 12 months follow-up after surgery. Samples form 12 healthy volunteers a nd 13 patients with chronic myelogenous leukemia served as controls. Interv entions: none. Measures: none. Results. We detected mRNA tyrosinase in the peripheral blood in 16 out of 2 7 melanoma patients studied. No tyrosinase mRNA was detected in any of the 25 samples from the controls. Two of the 16 positive cases developed a meta stasis within the next 12 months following testing. The other 14 positive c ases remain metastasis free for this period, as also did the test negative cases. Conclusions. Detection of blood circulating melanoma cells by a RT-PCR tech nique, may be helpful in defining melanoma patients who are at risk for the spread of the disease.