This page was reviewed under our medical and editorial policy by

Maurie Markman, MD, President, Medicine & Science

This page was updated on June 14, 2022.

Metastasis is the spread of cancer cells to distant areas of the body, often by way of the lymph system or bloodstream. Metastasis is sometimes mistakenly referred to by the generic misnomer metastatic carcinoma.

This article will cover:

What is metastatic cancer?

A metastatic cancer, or metastatic tumor, is one that has spread from the primary site of origin, or where it started, into different areas of the body.

When cancer becomes metastatic, doctors often use the verb “metastasized.” For example, your doctor may say that your cancer has metastasized, to explain that it’s spread from its original site to another part of the body.

In general, metastatic cancer is considered an advanced form of cancer, so your care team may also refer to it as advanced cancer or stage 4 cancer. However, advanced cancer isn’t necessarily metastatic, as some types are considered advanced when they’re large but haven’t yet spread beyond the area where they started.

How does cancer spread?

Cancer spreads when cancer cells travel through blood or lymph. Lymph is a clear fluid that circulates through the body via the lymph system, a network of organs, tissues and vessels. Before cancer cells can reach the bloodstream or lymph system, they must split off from the original tumor. This may happen if a tumor grows large and starts invading other tissue nearby. If a tumor grows into nearby lymph nodes or blood vessels, cancer cells can break off and enter the bloodstream or lymph system. As cancer cells travel through the body, they can settle down in another part of the body and start to form a new tumor.

Tumors formed from cells that have spread are called secondary tumors. The cancer may have spread to areas near the primary site, called regional metastasis, or to parts of the body that are farther away, called distant metastasis.

What are the steps of metastasis?

Metastasis occurs when cancer spreads beyond its original site to a distant part of the body. During this process, the cancer cells may:

  • Spread into tissue near the original cancer site
  • Invade the walls of nearby blood vessels or lymph nodes
  • Follow the bloodstream and lymphatic system to distant body parts
  • Invade distant small blood vessel walls and spread into the surrounding tissue
  • Form a small tumor (a metastatic tumor) in that tissue
  • Grow new blood vessels to supply blood to the new tumor so it grows

Most cancer cells don’t survive this process. If they do survive, they may not grow right away. In fact, some metastatic cancer cells may stay inactive for years.

Diagnosing metastatic cancer

Metastatic cancer is categorized by how far in the body the cancer has spread from the original site. For instance:

  • Advanced cancer: Cancer that has spread from the primary, or original, site to places in the body.
  • Locally advanced cancer: Cancer that has spread only to nearby tissues or lymph nodes.
  • Metastatic cancer: Cancer that has spread to distant parts of the body. 

The liver, lungs, lymph nodes and bones are common sites of metastasis.

Even when metastatic cancer spreads to a new location, it is still named after the area of the body where it started. For example, a person with breast cancer that has spread to the bones is said to have breast cancer with bone metastasis. If a cancer has spread widely throughout the body before it is discovered and it is unknown exactly where it started, it is called cancer of unknown primary origin.

Diagnosing metastatic cancer often involves various tests, including laboratory tests that analyze samples of blood, urine or other fluids, and imaging tests that create pictures of the inside of the body.

Doctors may order blood tests to help detect metastatic cancer, but these tests don’t always provide clear answers. Certain tumor markers or tumor proteins that indicate metastatic cancer  may also show up due to noncancerous conditions. Researchers are working to develop more accurate blood tests for detecting metastatic cancer. 

Sometimes, doctors may use these lab tests to look for tumor markers. Cancer cells or other cells may produce specific substances that help indicate the presence of cancer in your body. These substances are called tumor markers.

Some tumor markers may also be used to help determine whether cancer has metastasized, including:

Imaging tests may also be beneficial in diagnosing metastatic cancer. Imaging tests allow doctors to view the inside of different parts of the body using various techniques. Some common imaging tests include:

Cancer may become metastatic after treatment has concluded, or it may already be metastatic when first diagnosed.

If you undergo treatment and later find out that the cancer has metastasized, this generally means that the treatment was unable to completely eradicate the disease and some cancer cells were left behind. These cancer cells were then able to travel within the body and form a new tumor. In this case, you may need to undergo further testing to determine where the cancer has metastasized. It’s still considered part of the primary cancer. For example, if you had breast cancer and find out later that it has metastasized, it’s still considered breast cancer.

There are certain common areas where cancer tends to spread, depending on the type of cancer. For example, the following cancers often spread to these other sites:

Learn more about diagnosing cancer

Symptoms of metastatic cancer

You can have metastatic cancer with no symptoms. If you experience symptoms, they may vary depending on the type of cancer and where and it’s spread.

In general, however, there are certain symptoms that tend to come with metastatic cancer, including:

  • Fatigue
  • Unintentional weight loss
  • Pain
  • Difficulty breathing

There may also be symptoms specific to the site where the cancer has spread. For example:

  • Bone metastasis may cause pain and an increased risk of fractures.
  • Brain metastasis may cause headaches, seizures or dizziness.
  • Lung metastasis may cause difficulty breathing or shortness of breath.
  • Liver metastasis may cause jaundice (a yellowing of the skin and eyes) and abdominal swelling.

Treatment for metastatic cancer

Treatment for metastatic cancer aims to slow the growth or spread of the cancer. Treatment depends on the type of cancer, where it started, the size and location of the metastasis, and other factors.

Typically, metastatic cancer requires systemic therapy, or medications given by mouth or injected into the bloodstream to reach cancer cells throughout the body, such as chemotherapy or hormone therapy. Other treatments may include immunotherapy, radiation therapy, surgery, or a combination of these.

Before undergoing treatment for metastatic cancer, consider asking your doctor about enrolling in a clinical trial. Current treatments and new treatments for cancer are constantly being studied in clinical trials. Clinical trials offer access to novel treatments that may end up being more appropriate than the current standard-of-care options. There’s no guarantee that a clinical trial will benefit you, but it may potentially provide a new way forward, particularly if you’ve exhausted other options. Your care team can help you think about whether a clinical trial is right for you.

Even if metastatic cancer has stopped responding to treatment, many therapies may help ease side effects and improve quality of life. Palliative treatments, which may be the same treatments used to treat cancer, aim to relieve symptoms and side effects.

Coping with metastatic cancer

Having metastatic cancer may mean many different things depending on the type of cancer and other personal factors. In any case, it can be difficult to cope with. If you’ve been diagnosed with metastatic cancer, know that there are many people to lean on and resources to turn to. It’s important that you keep the lines of communication between you and your care team open. You should ask questions and voice your concerns in order to gain a full understanding of your diagnosis and what it means.

Some questions you may want to consider asking include:

  • What options do I have?
  • How effective are the potential treatment options?
  • Are the potential side effects of my treatment options worth the potential benefits?
  • What would the goals of treatment be?
  • What symptoms should I look out for?
  • What happens if I decide I don’t want treatment?

If, after reviewing your options, you feel you’re better off forgoing treatment in favor of minimizing potential side effects, there’s palliative care, which is focused on managing symptoms of cancer and improving quality of life. Some patients live with metastatic cancer for a long time and have a high quality of life by receiving palliative care.

It’s essential that you find a support system, or lean on an existing support system, to help you cope with metastatic cancer. Support can come in many forms, including loved ones, support groups, a counselor or psychologist or your care team.

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