Circulating tumor cell is a medical term used to describe cancer cells that have broken away from the primary tumor and are circulating in the bloodstream. However, this term is not the only one used to describe this type of cancer cell. Some synonyms for circulating tumor cells include disseminated tumor cells, circulating cancer cells, and blood-borne cancer cells. These terms all refer to the same phenomenon but are used interchangeably depending on the context in which they are being used. Regardless of the terminology used, circulating tumor cells are a significant factor in cancer spreading to other parts of the body, making their detection and management crucial for cancer patients' wellbeing.