One of the most insidious things about cancer is the way it can spread. I’m not especially a fan of the way it can keep coming back after treatment, either, but that’s a story for another day. The American Cancer Society talks about two different types of spread: local or regional spread and metastasis.
Local or regional spread is when a cancer extends beyond the organ in which it started. For example, a very large breast cancer could spread into the lymph nodes in the armpit or the lungs. Metastasis means that the cancer has moved to an entirely new part of the body, often through the lymph system or blood. Cancerous cells that break off from existing tumors can be carried into the lymph nodes or to other organs.
Why is the type of spread important? Local spread or metastasis can change treatment plans and affect a person’s chance of survival.
Why does cancer sometimes spread to other parts of the body? As mentioned above, sometimes cancerous cells can break off a tumor and move to another part of the body. Sometimes the tumor is growing so quickly that it moves to another local body part. Sometimes, a cancer remains or regrows after treatment (tumor removal, radiation therapy, etc.). A cancer can spread far before discovery, or reappear in a totally different area of the body.
Like I said at the start of this blog, cancer is sneaky. It doesn’t play fair. It doesn’t always give clues to where it came from, either. Sometimes, doctors can figure out where a metastasized cancer originated. Sometimes, they can’t.
Which is a better prognosis for a patient? I don’t know if there’s a good answer to this question. Both types of spread can be a bad sign. Many people who die from cancer have some form of metastasis occurring. But there are plenty of deadly, difficult to treat cancers that don’t spread, too.