Detection of circulating melanoma cells in the blood of melanoma patients: A preliminary study

Significant prognostic heterogeneity exists within the substages of melanoma; therefore, novel prognostic biomarkers are needed to provide information on the risk of recurrence. Limited available data suggest prognostic significance for circulating melanoma cells (CMCs); there is a need for a sensitive, reproducible, and standardized identification technique. Using a semiautomated technology, we sought to determine whether CMCs could be identified reliably in stage I-IV melanoma patients and whether the presence of CMC correlated with known prognostic factors. CMCs were detected in the peripheral blood (7.5 ml) of patients with stage I-IV melanoma (n=89) using the CellSearch system. CD146 + cells were immunomagnetically enriched; nucleated HMW-MAA +/CD45-/CD34-cells were considered CMCs. One or more CMCs was detected in 45% of all patients, varying with stage of disease (stages I/II, III, and IV: 35, 44, and 86%, respectively; P=0.03, for stage I/II vs. stage IV); 55% had one CMC, 32% had two CMCs, and 13% had three or more CMCs identified. The presence of CMCs in the blood was associated with histologic subtype, particularly in patients with stage I/II disease (superficial spreading 18% vs. acral lentiginous 75%). Using a semiautomated technique, CMCs can be identified in a significant number of melanoma patients. These data support further study with longer follow-up and longitudinal/serial time points to better determine the identification rates and prognostic significance of CMCs in stage I-IV melanoma patients.