Tumour DNA can get into the blood-stream in one of three ways.
- Apoptosis: Apoptosis is the process of natural cell death. As tumour cells die, DNA is released into the blood.
- Necrosis: Necrosis is when something external to the cell has caused the cells to die, releasing their contents into the blood.
- Secretion: Secretion is the natural process by which contents of a cell move from the inside to the outside.