When does a melanoma metastasize? Implications for management.

Selecting which patients with clinically-localized melanoma require treatment other than wide excision of the primary tumor is based on the risk or presence of metastatic disease. This in turn is linked to survival. Knowing if and when a melanoma is likely to metastasize is therefore of great importance. Several studies employing a range of different methodologies have suggested that many melanomas metastasize long before the primary lesion is diagnosed. Therefore, waiting for dissemination of metastatic disease to become evident before making systemic therapy available to these patients may be less effective than giving them post-operative adjuvant therapy initially if the metastatic risk is high. The identification of these high-risk patients will assist in selecting those to whom adjuvant systemic therapy can most appropriately be offered. Further studies are required to better identify high-risk patients whose primary melanoma is likely to have already metastasized.