Abstract
Whole-genome sequencing has made a significant impact on cancer research, but traditional bulk methods fail to detect information from rare cells. Recently developed single-cell sequencing methods have provided new insights and unprecedented details about cancer progression and diversity. These advancements also enable the investigation of rare cells, such as circulating tumor cells (CTCs) derived from cancer patients. In this review, we outline various single-cell sequencing techniques that can elucidate the molecular properties of CTCs. In addition, we explain the drawbacks that need to be overcome for each method.