The short answer
Metastatic cancer is cancer that has spread from where it started to a distant part of the body. It keeps the name of the original cancer, such as metastatic breast cancer. There are treatments for most types, often aimed at controlling the cancer and relieving symptoms.
Metastatic cancer is cancer that has spread from where it started to a distant part of the body.
For many types of cancer, metastatic cancer is also called stage 4 cancer.
Metastatic cancer keeps the name of the primary (original) cancer, such as metastatic breast cancer.
The most common places cancer spreads are the bone, liver, and lung.
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The full explanation.
The simple version
Cancer that spreads from where it started to a distant part of the body is called metastatic cancer. For many types of cancer, it is also called stage 4 cancer. The process by which cancer cells spread to other parts of the body is called metastasis.
Doctors look at metastatic cancer cells under a microscope and test them in other ways. The cells have features like the primary (original) cancer. They do not look like the cells in the place where the metastatic cancer was found. That is how doctors can tell the cancer has spread from another part of the body.
Metastatic cancer keeps the name of the cancer it came from, no matter where it travels.
Why the name stays the same
Metastatic cancer has the same name as the primary cancer. Take breast cancer that spreads to the lung. It is called metastatic breast cancer, not lung cancer. And it is treated as stage 4 breast cancer, not as lung cancer.
Sometimes doctors cannot tell where a metastatic cancer started. That type is called cancer of unknown primary origin, or CUP.
How cancer spreads
Cancer cells spread through the body in a series of steps. These steps include:
- growing into, or invading, nearby normal tissue.
- moving through the walls of nearby lymph nodes or blood vessels.
- traveling through the lymphatic system and bloodstream to other parts of the body.
- stopping in small blood vessels at a distant site, invading the vessel walls, and moving into the tissue around them.
- growing in this tissue until a tiny tumor forms.
- causing new blood vessels to grow. That creates a blood supply, which lets the metastatic tumor keep growing.
Most of the time, spreading cancer cells die at some point along the way. But if conditions stay right for the cancer cells at every step, some of them can form new tumors elsewhere in the body. Metastatic cancer cells can also lie inactive at a distant site for many years before they start growing again, if at all.
Where cancer spreads
Cancer can spread to almost any part of the body. But different types of cancer tend to spread to certain areas more than others. The most common sites where cancer spreads are bone, liver, and lung.
Here are the main sites where common cancers spread, not counting the lymph nodes.
- Bladder: bone, liver, lung.
- Breast: bone, brain, liver, lung.
- Colon: liver, lung, peritoneum.
- Kidney: adrenal gland, bone, brain, liver, lung.
- Lung: adrenal gland, bone, brain, liver, other lung.
- Melanoma: bone, brain, liver, lung, skin, muscle.
- Ovary: liver, lung, peritoneum.
- Pancreas: liver, lung, peritoneum.
- Prostate: adrenal gland, bone, liver, lung.
- Stomach: liver, lung, peritoneum.
Possible symptoms
Metastatic cancer does not always cause symptoms. When symptoms do happen, what they feel like and how often they come depend on the size and location of the metastatic tumors. Some common signs include:
- pain and fractures, when cancer has spread to the bone.
- headache, seizures, or dizziness, when cancer has spread to the brain.
- shortness of breath, when cancer has spread to the lung.
- jaundice (yellowing of the skin or eyes) or swelling in the belly, when cancer has spread to the liver.
Treatment goals
There are treatments for most types of metastatic cancer. Often the goal is to control the cancer by stopping or slowing its growth. Some people live for years with metastatic cancer that is well controlled.
Other treatments may improve quality of life by easing symptoms. That kind of care is called palliative care. It can be given at any point during cancer treatment.
Which treatment a person has depends on several things. The type of primary cancer. Where it has spread. Treatments they have had in the past. And their general health.
For cancer-specific next-step guides, see metastatic breast cancer, stage 4 lung cancer, metastatic colorectal cancer, metastatic prostate cancer, and oligometastatic cancer.
Looking ahead
If a person is told their cancer can no longer be controlled, they and their loved ones may want to talk about end-of-life care. Palliative care is always available, whether or not someone chooses to keep treating the cancer. It is there to control symptoms of cancer and side effects of treatment.
Researchers keep studying new ways to kill primary and metastatic cancer cells, or to stop them growing. That work includes helping the immune system fight cancer, blocking the steps that let cancer cells spread, and targeting specific genetic changes in tumors.
Even after cancer spreads, there are treatment options, and care to help people feel better is always available.
Words to know
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Common questions
What is metastatic cancer?
Metastatic cancer is cancer that spreads from where it started to a distant part of the body. The process by which cancer cells spread is called metastasis. For many types of cancer, metastatic cancer is also called stage 4 cancer.
Why is metastatic breast cancer in the lung not called lung cancer?
Metastatic cancer has the same name as the primary (original) cancer. Breast cancer that spreads to the lung is called metastatic breast cancer, not lung cancer, and it is treated as stage 4 breast cancer. Under a microscope, the cancer cells look like breast cancer cells, not lung cells, which is how doctors can tell where it came from.
Where does cancer most often spread?
Cancer can spread to almost any part of the body, but the most common sites are the bone, liver, and lung. Different types of cancer are more likely to spread to certain areas than others.
Does metastatic cancer always cause symptoms?
No. Metastatic cancer does not always cause symptoms. When symptoms do occur, they depend on the size and location of the tumors. Examples include bone pain or fractures when cancer spreads to bone, headaches or seizures when it spreads to the brain, shortness of breath when it spreads to the lung, and jaundice or belly swelling when it spreads to the liver.
Can metastatic cancer be treated?
There are treatments for most types of metastatic cancer. Often the goal is to control the cancer by stopping or slowing its growth, and some people can live for years with metastatic cancer that is well controlled. Other treatments, called palliative care, aim to improve quality of life by relieving symptoms. Treatment depends on the primary cancer type, where it has spread, past treatments, and overall health.
What is cancer of unknown primary?
Sometimes doctors find metastatic cancer but cannot tell where it started. This is called cancer of unknown primary origin, or CUP. The National Cancer Institute has more information on its Carcinoma of Unknown Primary page.
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Sources last checked: 2026-07-21 what this meansLast updated: 2026-08-05Next planned review: 2028-07-21
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and checked line by line against the sources listed on it. That confirms the sources support what the page says. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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