Metastatic Cancer: When Cancer Spreads

The simple versionExplain▾

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.

When metastatic cancer cells are looked at under a microscope and tested in other ways, they have features like the primary (original) cancer, not like the cells in the place where the metastatic cancer is found. This is how doctors can tell that 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 sameExplain▾

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 4 breast cancer, not as lung cancer.

Sometimes when people are diagnosed with metastatic cancer, doctors cannot tell where it started. This type is called cancer of unknown primary origin, or CUP.

How cancer spreadsExplain▾

Cancer cells spread through the body in a series of steps. These steps include:

1. growing into, or invading, nearby normal tissue
2. moving through the walls of nearby lymph nodes or blood vessels
3. traveling through the lymphatic system and bloodstream to other parts of the body
4. stopping in small blood vessels at a distant location, invading the blood vessel walls, and moving into the surrounding tissue
5. growing in this tissue until a tiny tumor forms
6. causing new blood vessels to grow, which creates a blood supply that lets the metastatic tumor keep growing

Most of the time, spreading cancer cells die at some point in this process. But as long as conditions stay favorable for the cancer cells at every step, some of them can form new tumors in other parts of the body. Metastatic cancer cells can also stay inactive at a distant site for many years before they begin to grow again, if at all.

Where cancer spreadsExplain▾

Cancer can spread to almost 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 bone, liver, and lung.

Some examples of the main sites where common cancers spread (not counting the lymph nodes) include:

• 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 symptomsExplain▾

Metastatic cancer does not always cause symptoms. When symptoms do occur, what they are like and how often they happen 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 goalsExplain▾

There are treatments for most types of metastatic cancer. Often, the goal of treating metastatic cancer is to control it by stopping or slowing its growth. Some people can live for years with metastatic cancer that is well controlled.

Other treatments may improve quality of life by relieving symptoms. This type of care is called palliative care, and it can be given at any point during cancer treatment.

The treatment a person may have depends on the type of primary cancer, where it has spread, treatments they have had in the past, and their general health.

Looking aheadExplain▾

If a person is told their cancer can no longer be controlled, they and their loved ones may want to discuss end-of-life care. Whether or not someone chooses to continue treatment to shrink the cancer or control its growth, palliative care is always available to control symptoms of cancer and side effects of treatment.

Researchers continue to study new ways to kill or stop the growth of primary and metastatic cancer cells. These include helping the immune system fight cancer, disrupting the steps that allow cancer cells to 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.