Cancer cells can spread locally by moving into nearby normal tissue. Cancer can also spread regionally, to nearby lymph nodes, tissues, or organs. And it can spread to distant parts of the body. When this happens, it is called metastatic cancer. For many types of cancer, it is also called stage IV cancer. The process by which cancer cells spread to other parts of the body is called metastasis.
When observed under a microscope and tested in other ways, metastatic cancer cells have features like that of the primary cancer and not like the cells in the place where the cancer is found. This is how doctors can tell that it is cancer that has spread from another part of the body.
Cancer cells spread through the body in a series of steps:
- Growing into, or invading, nearby normal tissue.
- Moving through the walls of nearby lymph nodes or blood.
- Traveling through the lymphatic system and bloodstream.
- Stopping in small blood vessels at a distant location, invading the blood vessel walls, and moving into surrounding tissue.
- Growing in this tissue until a tiny tumor forms.
- Causing new blood vessels to grow, which creates a blood supply that allows the tumor to continue growing.
