Aims: To review the role of tyrosinase RT-PCR in the detection of clinically occult metastatic disease, both within the regional lymph nodes and peripheral blood of patients with malignant melanoma. Secondly, to assess whether the detection of such minimal disease has clinical implications for patients with melanoma.
Methods: A review of the literature was undertaken by searching the MEDLINE database for the period 1966-2002 without any language restrictions. Keywords included 'Molecular staging of melanoma', 'Reverse transcription polymerase chain reaction', 'Malignant melanoma' and 'Tyrosinase'.
Conclusions: Detection of tyrosinase RT-PCR positive cells within the peripheral blood correlates with the clinical stage of malignant melanoma, the primary tumour thickness and other known prognostic indicators. Positive tyrosinase RT-PCR is associated with a reduction of disease-free survival and overall survival. Current studies demonstrate a higher rate of recurrence in RT-PCR positive patients with clinical stage II and III disease. Implications of a positive result within the regional lymph nodes are less well defined. A significant correlation has been demonstrated between positive results and increasing primary melanoma thickness. However, a large number of false-positive results have been demonstrated, due to benign naevi and schwann cells, which may hamper any statistically significant conclusions being reached.