What Does It Mean When Cancer Has Metastasized?

There are three ways cancer can metastasize:

• Into the tissue that directly surrounds the primary tumor
• Through the body’s blood to other parts of the body, including organs or bones
• Through the lymphatic system to spread into lymph nodes

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There are exceptions. If the cancer has spread to the lymph node network linked with the primary tumor, the cancer can still be a stage 2 or stage 3 disease and could potentially be cured. For example, breast cancer that spreads to the nearby lymph nodes, such as under the arm, or near the collarbone or breastbone, is not considered metastatic.

When a specific type of cancer spreads distantly to another part of the body, it is still defined and treated according to where it comes from, says Rebecca Shatsky, MD, a UC San Diego medical oncologist who specializes in treating breast cancer.

“For example, breast cancer that has spread to the bone is still called breast cancer, not bone cancer,” she says. “This terminology is usually only used to describe solid tumor cancers, not cancer derived from blood cells.”

Each type of cancer tends to have places in the body where it likes to metastasize and can vary widely depending on the primary tumor type, Dr. Shatsky says.

“We do know that certain types of cancer have a predilection for certain organs,” she says. “For example, breast cancer and prostate cancer frequently spread to the bone.”

The metastasis process can differ among the types of cancer, she says. But the general process is that early on in the development of a primary tumor, cells arise that have the ability to escape from the original tumor.

“These cells can escape and then can hide in other places in the body — the bones, the organs — where they can then form tumors in other places of the body,” she says. “This happens because the cancer’s goal, just like our normal cells' goal, is to grow and survive.”

Certain parts of the body are more problematic if cancer spreads to them, Shatsky says, for example when cancer spreads to an organ that is critical for day-to-day survival, such as the brain, cerebral spinal fluid, the liver, or the lungs.

“Some types of cancer are very aggressive and contain more cells that have the ability to spread to other parts of the body, while other cancers contain little to no cells that have the ability to spread distantly,” she says. “For example, cancers of the skin such as basal cell carcinoma or squamous cell carcinoma very rarely metastasize distantly, whereas lung cancers, pancreatic cancer and melanoma frequently metastasize distantly if they are not caught and treated extremely early.”

When cancer metastasizes, the symptoms depend on where in the body the cancer has spread, Shatsky says. That means there is not one set list of symptoms to look for.

For example:

• Cancer that has spread to the bone can cause bone pain.
• Cancer that has metastasized to the liver may create symptoms of bloating or a swollen belly, decreased appetite or being full quickly, and jaundice.
• Cancer that has spread to the brain could cause dizziness, headaches, and seizures.
• Cancer that has spread to the lungs could cause shortness of breath.

In some cases, the metastasis doesn’t cause any symptoms and is detected only through imaging.

There are some general symptoms of metastasis. Those include extreme fatigue, night sweats, and weight loss that doesn’t have another explanation.

People can be diagnosed with metastatic cancer in several ways.

Sometimes metastatic cancer is discovered after a patient has been diagnosed with a primary cancer and has already undergone some treatment. It also could be discovered in the process of doing scans or imaging when the primary cancer is diagnosed or during the removal of a primary cancer tumor.

If metastasized cancer is found without another cancer being detected first, it’s usually because the person has a symptom that leads to imaging, Shatsky says. For example, if someone has bone pain, cough, or headaches, their providers decide to do imaging such as a CT, MRI, PET scan, or bone scan. Those scans would detect cancer if it’s present.

Although cancer that has metastasized, or stage 4 cancer, is not curable, it can be treated. These options depend on the type of cancer, its severity, and the patient’s wishes, Shatsky says.

“The treatment focus for stage 4 solid cancers is controlling the cancer, prolonging life and controlling symptoms caused by the cancer,” she says.

For example, if a patient has metastatic breast cancer, the provider will treat the cancer that has spread in the same way as the original cancer in the breast. Treatments could include chemotherapy, hormone therapy, immunotherapy, radiation therapy, and targeted therapy.

Doctors call this type of treatment “palliative intent treatment.” The goal is “to control the cancer with the least toxic therapies to maintain quality of life for as long as possible,” she says. The treatment is generally lifelong, because most cancers will start growing again if treatment stops.

It’s possible for patients to live for many years with metastasized cancer. A few types of metastases can be cured, including melanoma and colon cancer.

When evaluating medical information online, Shatsky says to be an informed consumer.

“It’s extremely important to go to evidence-based resources for information on cancer in general, as there is an enormous amount of misinformation about cancer out there,” Shatsky says.

• Metastatic cancer occurs when cancer cells from a primary tumor spread to distant parts of the body.
• Although metastatic cancer generally cannot be cured, treatment options like chemotherapy, immunotherapy, and hormone therapy can help manage it and improve quality of life.
• Survival rates for metastatic cancer depend on the type of cancer and where it has spread. With treatment, patients can live for many years.