BACKGROUND:Metastasis is the primary cause of mortality in cancer patients.Therefore,elucidating the genetics and epigenetics of metastatic tumor cells and the mechanisms by which tumor cells acquire metastatic properties constitute significant challenges in cancer research.OBJECTIVE:To summarize the current understandings of the specific genotype and phenotype of the metastatic tumor cells.METHOD and RESULT:In-depth genetic analysis of tumor cells,especially with advances in the next-generation sequencing,have revealed insights of the genotypes of metastatic tumor cells.Also,studies have shown that the cancer stem cell (CSC) and epithelial to mesenchymal transition (EMT) phenotypes are associated with the metastatic cascade.CONCLUSION:In this review,we will discuss recent advances in the field by focusing on the genomic instability and phenotypic dynamics of metastatic tumor cells.