Understanding How Cancer Can Spread

Our bodies are made up of trillions of cells. Normally, new cells replace old or damaged cells once they die off. If a cell’s DNA becomes damaged, our immune system can control a small number of these abnormal cells, keeping them from causing further damage to our bodies. Cancer occurs when the number of abnormal cells becomes too much for our immune system to handle.

Why Does Cancer Spread?

Where cancer spreads is linked to where it starts. Most cancer cells that break away from the primary tumor are carried in the blood or lymph system until they get trapped in the next “downstream” organ or set of lymph nodes. Breast cancer, for example, often spreads to underarm lymph nodes and, but rarely spreads to lymph nodes in the belly. Many cancers spread to the lungs because the body pumps blood from the rest of the body through the lungs’ blood vessels before sending it to other parts of the body.

How Does Cancer Spread?

Cancer that spreads to a distant part of the body is called metastatic cancer. When cancer cells break away from a tumor, they can travel through the bloodstream or lymph system. If the cells travel in the lymph system, they could end up settling in nearby lymph nodes or other organs. It’s more common for cancer cells to travel through the bloodstream. Once these cells are in the blood, they can travel anywhere.

These are the steps cancer cells must go through before spreading to other parts of the body:

  • They must find ways to break away from the original tumor and enter the bloodstream or lymph system.
  • They need to attach to the wall of a blood or lymph vessel and move into a new body part.
  • They need to find ways to grow and thrive in their new location.
  • They must be able to avoid attacks from the body’s immune system.

How Fast Does Cancer Spread?

How fast cancer spreads depends on the cancer type. Cancer cells that have more genetic damage (poorly differentiated) typically grow faster than cells with less genetic damage (well-differentiated). 

Some cancers that generally grow slower include chronic lymphocytic leukemia, most types of prostate cancer, and colon and rectal cancer.

Examples of fast-growing cancers include lung cancer, acute lymphoblastic leukemia, and large B-cell lymphoma.

Which Type of Cancer Spreads the Fastest?

The fastest-moving cancers are pancreatic, brain, esophageal, liver, and skin. Pancreatic cancer is one of the most dangerous types of cancer because it’s fast-moving and there’s no method of early detection.

How Do You Know if Cancer Has Spread?

Metastatic cancer doesn’t always cause symptoms. When they do occur, the symptoms you may experience and how long they last depend on the size and location of the metastatic tumors. Some common symptoms of metastatic cancer include:

  • Loss of energy and feeling weak. This can become so pronounced that you may have a hard time getting out of bed, bathing, or getting dressed.
  • Weight loss without trying
  • Pain
  • Shortness of breath or trouble breathing

Connect with a Provider

If you’re experiencing any of the symptoms described above, have a family history of cancer, or are concerned that you may have cancer, take a health risk assessment to determine if you’re at risk for cancer.


Next Steps and Useful Resources:

How to Help Reduce Your Risk for Colon Cancer
Exercise and Prostate Cancer: Is It Safe?
Types of Leukemia
Your Diet & Your Colon: Something You Need to Know

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