Circulating tumor cells (CTC) or sentinel tumor cells eventually find a fertile ground to grow new tumors. To do this, they need to reverse the EMT process and become colony-forming cells again. This process is simply called the Mesenchymal to Epithelial Transition (MET). This is how these free-floating cancer pioneers settle down and become new tumors.
Critical to tumor development is the ability of these cells to turn off a process called “programmed cell death,” or Apoptosis. Cells need to die.
In particular, when they detach from other cells, a programmed cell death is triggered, but some tumor cells are able to silence this program and do not die. Programmed death is a natural process of life and a natural protection against tumor formation. In fact when cell growth goes out of control, programmed cell death is activated.
In programmed cell death, cells simply shrivel and die causing no immune response. When cells are destroyed by toxins or other non-natural processes, they spill their contents into the blood stream, which triggers an immune response and inflammation. Millions upon millions of cells die in your body each day without any immune response or inflammation. This is because of Programmed Cell Death.
Another critical aspect of tumor growth is the ability of these cells to turn off the genetic message inside them that controls programmed cell death. This allows them to replicate endlessly and form tumors.