Diversity of circulating tumor cells in peripheral blood: Detection of heterogeneous BRAF mutations in a patient with advanced melanoma by single-cell analysis

Therapies targeting the MAPK signal pathway have been used to improve survival of patients with advanced melanoma [1]. However, many patients exhibit a short response and recurrence within several months after therapy, possibly related to heterogeneity arising due to genetic and epigenetic instability in melanoma cells. Circulating tumor cells (CTCs) released from primary or metastatic tumors are a non-invasive tool that could be used to characterize changes in tumors over time. Assuming that the CTC population represents the distributed tumor burden, characterization of these cells could provide a complementary sample for monitoring of tumor characteristics [2].