Lack of prognostic importance of reverse-transcriptase polymerase chain reaction detection of circulating messenger RNA in patients with melanoma

Background: Molecular serologic markers for detecting early melanoma metastases have been described. The objective of this study was to determine whether reverse-transcriptase polymerase chain reaction detection of circulating tyrosinase messenger RNA (mRNA) can identify the presence of subclinical metastases and predict subsequent clinical recurrence in surgically treated melanoma patients who are at significant risk for relapse. Methods: Preoperative peripheral blood samples of disease-free melanoma patients, disease stage ranging from I to IV, were analyzed for the presence of tyrosinase mRNA by semiquantitative reverse-transcriptase polymerase chain reaction as a putative marker for circulating melanoma cells. Multivariate analysis was performed to evaluate the prognostic value of tyrosinase mRNA in the blood and in the correlating pathologic stage of disease with recurrence and survival. Results: The study group consisted of 96 patients. The mean age was 54 years (range, 24 to 83 years). The mean Breslow thickness was 3 mm (range, 0.9 to 21 mm). Circulating melanoma cells were detected in 66 patients (69 percent). Blood polymerase chain reaction positivity by American joint Committee on Cancer stage was as follows: stage I, 19 of 28 patients (68 percent); stage II, 17 of 25 patients (68 percent); stage III, 28 of 41 patients (68 percent); and stage IV, two of two patients (100 percent). Tyrosinase detection was not associated with stage of disease (p = 0.77). At a median follow-up of 30 months, disease recurred in 21 patients (22 percent), and 15 patients (16 percent) died. Disease stage of the patients correlated with recurrence (p < 0.0001) and death (p < 0.0001). The finding of mRNA tyrosinase in peripheral blood samples was not associated with recurrcnce (p = 0.1) or death (p = 0.77). Conclusions: The use of polymerase chain reaction to detect circulating tyrosinase mRNA in peripheral blood does not correlate with traditional prognostic indicators in patients with cutaneous melanoma and does not appear to be an effective prognostic tool.