In metastasis, cancer cells break away
from where they first formed (primary cancer), travel through the blood
or lymph system, and form new tumors (metastatic tumors) in other parts
of the body. The metastatic tumor is the same type of cancer as the
primary tumor.
What Is Metastatic Cancer?
The main reason that cancer is so serious is its ability to spread in
the body. 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 (four) 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.
Metastatic cancer has the same name as the primary cancer. For
example, breast cancer that spreads to the lung is called metastatic
breast cancer, not lung cancer. It is treated as stage IV breast cancer,
not as lung cancer.
Sometimes when people are diagnosed with metastatic cancer, doctors
cannot tell where it started. This type of cancer is called cancer of
unknown primary origin, or CUP. See the Carcinoma of Unknown Primary page for more information.
When a new primary cancer occurs in a person with a history of
cancer, it is known as a second primary cancer. Second primary cancers
are rare. Most of the time, when someone who has had cancer has cancer
again, it means the first primary cancer has returned.
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 location, invading the blood vessel walls, and moving into the 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
Most of the time, spreading cancer cells die at some point in this
process. But, as long as conditions are favorable for the cancer cells
at every step, some of them are able to form new tumors in other parts
of the body. Metastatic cancer cells can also remain inactive at a
distant site for many years before they begin to grow again, if at all.
Where Cancer Spreads
Cancer can spread to most any part of the body, although different
types of cancer are more likely to spread to certain areas than others.
The most common sites where cancer spreads are the bone, liver, and
lung. The following list shows the most common sites of metastasis, not
including the lymph nodes, for some common cancers:
Common Sites of Metastasis
Cancer Type
Main Sites of Metastasis
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
Rectal
Liver, lung, peritoneum
Stomach
Liver, lung, peritoneum
Thyroid
Bone, liver, lung
Uterus
Bone, liver, lung, peritoneum, vagina
Symptoms of Metastatic Cancer
Metastatic cancer does not always cause symptoms. When symptoms do
occur, their nature and frequency will depend on the size and location
of the metastatic tumors. Some common signs of metastatic cancer
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 or swelling in the belly, when cancer has spread to the liver
Treatment for Metastatic Cancer
Once cancer spreads, it can be hard to control. Although some types
of metastatic cancer can be cured with current treatments, most cannot.
Even so, there are treatments for all patients with metastatic cancer.
The goal of these treatments is to stop or slow the growth of the cancer
or to relieve symptoms caused by it. In some cases, treatments for
metastatic cancer may help prolong life.
The treatment that you may have depends on your type of primary
cancer, where it has spread, treatments you’ve had in the past, and your
general health. To learn about treatment options, including clinical
trials, find your type of cancer among the PDQ® Cancer Information Summaries for Adult Treatment and Pediatric Treatment.
When Metastatic Cancer Can No Longer Be Controlled
If you have been told you have metastatic cancer that can no longer
be controlled, you and your loved ones may want to discuss end-of-life
care. Even if you choose to continue receiving treatment to try to
shrink the cancer or control its growth, you can always receive
palliative care to control the symptoms of cancer and the side effects
of treatment. Information on coping with and planning for end-of-life
care is available in the Advanced Cancer section.
Ongoing Research
Researchers are studying new ways to kill or stop the growth
of primary and metastatic cancer cells. This research includes finding
ways to help your immune system fight cancer. Researchers are also
trying to find ways to disrupt the steps in the process that allow
cancer cells to spread. Visit the Metastatic Cancer Research page to stay informed of ongoing research funded by NCI.
Updated: July
11, 2016
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