Results: The PCR assay was always negative in normal individuals and in subjects with non-MM metastatic cancer, while it was positive in 16 of 32 patients with disseminated MM. Five of eight patients who were PCR-positive before node dissection vs one of 10 who were PCR-negative relapsed within 6 months after surgery. In highrisk but apparently disease-free patients, the risk of relapse within the next 6 months was 3.8 times higher after a positive test result. In patients with distant metastases, a positive PCR predicted rapid disease progression.

Conclusions: These data suggest that PCR detection of circulating melanocytes can be considered as a marker for rapid postoperative relapse after node dissection in patients with MM with regional node metastases, for shortterm relapse in high-risk disease-free patients, and for rapid and severe progression in patients with distant metastases. This test may have a crucial interest in the treatment of patients with MM.