What Is Metastatic Cancer?

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Metastatic cancer is cancer that has spread from the part of the body where it started (the primary site) to other parts of the body. Almost all types of cancer have the ability to metastasize, but whether they do depends on a variety of individual factors. Understanding metastases is a critical area of cancer research, as metastatic disease is responsible for roughly 90% of cancer deaths.

Doctor touching patient's arm in encouragement

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Common Sites Where Cancer Spreads
Cancer Type Main Sites of Metastasis
Breast Bone, brain, liver, lung
Colon  Liver, lung, peritoneum
Lung Adrenal gland, bone, brain, liver, other lung
Melanoma  Bone, brain, liver, lung, skin, muscle
Prostate  Adrenal gland, bone, liver, lung
Stomach  Liver, lung, peritoneum

Types of Metastatic Cancer

Cancer that has spread to another area is given the same name as the original cancer. For example, breast cancer that spreads to the liver is called metastatic breast cancer, not liver cancer. This is because the cancer started in the breast and the treatment used is for breast cancer. Common types of metastatic cancer include:

Breast Cancer

Metastatic breast cancer, also known as stage IV breast cancer, is diagnosed when cells from a primary tumor in the breast migrate from the breast to other parts of the body.

At the time of diagnosis, approximately 6% of patients have metastatic disease and more than 150,000 breast cancer survivors are living with metastatic disease, 75% of whom were originally diagnosed with stage I-III cancer.

Lung Cancer

Nearly 40% of those newly diagnosed with lung cancer already have metastatic disease in other parts of the body, which is one of the reasons that the 5-year relative survival rate for lung cancer is low—19% overall (16% for men and 23% for women).

Brain Cancer

Most primary brain tumors do not usually spread beyond the central nervous system. Metastatic tumors to the brain affect nearly one in four patients with cancer, or an estimated 150,000 people a year. Up to 40% of people with lung cancer will develop metastatic brain tumors.

Bone Cancer

Primary bone cancer is rare. It accounts for much less than 1% of all new cancers diagnosed. In 2018, an estimated 3,450 new cases of primary bone cancer were diagnosed in the United States.

In adults, cancerous tumors that have metastasized to the bone are much more common than primary bone cancer. For example, at the end of 2008, an estimated 280,000 adults ages 18–64 years in the United States were living with metastatic cancer in bones.

Cancer of Unknown Primary Origin (CUP)

Carcinoma of unknown primary origin (CUP) is a rare disease in which malignant cells are found in the body but the place the cancer began is not known.

Sometimes doctors find the place where cancer has metastisized but cannot find where in the body the cancer first began to grow. For about 3% of cancer patients, the original cancer site is never found.

Metastatic Cancer Symptoms

Metastatic cancer does not always cause symptoms. However, there may be symptoms related to the site of metastases such as:

  • Pain and fractures, when cancer has spread to the bone
  • Headache, seizures, or dizziness, when cancer has spread to the brain
  • Dhortness of breath, when cancer has spread to the lung
  • Jaundice or swelling in the belly, when cancer has spread to the liver

Tell Your Doctor If…

You are experiencing unexplained aches and pains, notice an unusual lump or swelling, have a persistent, worsening cough, or unintentional weight loss.

Not every person with cancer has symptoms. But spotting cancer early saves lives, so tell your doctor if you notice anything that isn’t normal for you.

Causes

For decades, scientists have focused their efforts on explaining the process of cancer metastasis, with the aim of finding a way to inhibit this process. These mechanisms only describe the process of cancer metastasis but do not explain why cancer would metastasize in the first place.

Cancer is a genetic disease—that is, cancer is caused by certain changes to genes that control the way our cells function, especially how they grow and divide. Although cancer involves genes, inherited gene mutations play a major role in only about 5 to 10% of all cancers.

Cancer cells must go through several steps to spread to new parts of the body:

  • They must find ways to break away from the original tumor and enter the bloodstream or lymph system.
  • They need to attach to the wall of a blood or lymph vessel and move into a new body part.
  • They need to find ways to grow and thrive in their new location.
  • They must be able to avoid attacks from the body’s immune system.

Researchers are also examining why some cancers spread while others don't. For example, the most common skin cancer—basal cell skin carcinoma—hardly ever spreads but the rarer skin cancer—melanoma—often metastasizes, unless it can be treated in time.

Risk Factors

Limiting your exposure to avoidable risk factors may lower your risk of developing certain cancers.

  • Age: One-quarter of new cancer cases are diagnosed in people aged 65 to 74.
  • Alcohol: Drinking alcohol can increase your risk of cancer of the mouth, throat, esophagus, larynx, liver, and breast. The more you drink, the higher your risk.
  • Immunosuppression: Transplant recipients and people with HIV/AIDS have a weakened immune system which is less able to detect and destroy cancer cells or fight off infections that cause cancer.
  • Obesity: People who are obese may have an increased risk of several types of cancer, including cancers of the breast, colon, rectum, endometrium, esophagus, kidney, pancreas, and gallbladder.
  • Sunlight: About 90% of non-melanoma skin cancers are associated with exposure to ultraviolet (UV) radiation from the sun.
  • Tobacco: Smoking causes about 20% of all cancers and about 30% of all cancer deaths in the United States.

Diagnosis

There is no one test to check for metastasis. Various tests will reveal different things. The tests that are done are determined by the type of primary cancer and/or any symptoms that need to be investigated.

Blood Tests

Routine blood tests such as liver enzymes may be elevated in the presence of liver metastasis. However, these blood tests are often normal, even in people with advanced disease.

Tumor Markers

Some cancers have specific blood tests called tumor markers that can be helpful in following the disease after it has been diagnosed. If these levels rise, it can be an indication that the disease is active or progressing.

Ultrasound

An ultrasound scan is a good tool for identifying fluid in the abdomen and can distinguish fluid-filled liver cysts from more solid, suspicious-appearing masses within the liver or the pelvis.

CT Scan (Computed Tomography)

A CT scan can be used to scan the head, neck, chest, abdomen, and pelvis. When done with contrast, it is especially good at identifying masses within the lymph nodes, lungs, liver, or other structures.

MRI (Magnetic Resonance Imaging)

An MRI is best used to define potential damage to the spinal cord if there are bone metastasis in the vertebra of the back or to characterize brain metastases.

Bone Scan

A bone scan is a nuclear imaging technique in which a small amount of radioactive material is injected into your vein to highlight areas of bone damage or disease. It is most useful at evaluating the whole body for evidence of bone damage that is suspicious for cancer.

PET Scan (Positron Emission Tomography)

The PET scan uses a mildly radioactive drug to show up areas of your body where cells are more active than normal. It can be used to find out where and whether cancer has spread. 

Biopsy

A biopsy is the main way doctors diagnose most types of cancer. During a biopsy, a doctor removes a small amount of tissue to examine under a microscope. The type of biopsy you receive depends on where the possible tumor is located.

Treatment

Often, the goal of treating metastatic cancer is to control it by stopping or slowing its growth, rather than providing a cure. Treatment success depends on various factors such as rate of growth, the extent of cancer spread, and how it responds to treatment, which may take the form of chemotherapy, radiotherapy, immunotherapy, or surgery.

In some clinical situations, metastases may be treated in specific ways.

Brain

Depending on the number of tumors and the extent of the disease in the rest of the body, treatment options may include surgery (in very specific cases), radiation therapy, gamma knife surgery, chemotherapy and/or steroids.

Bone

If the bone metastases are not causing pain or danger of breaking, they may be monitored or treated with drug therapy. If there is pain or the bone is fragile, radiation may be given to the location of the damage.

Lung

The treatment of lung metastases depends on the extent of the metastases as well as the primary cancer. If the metastasis is causing fluid to form around the lung, a procedure called thoracentesis may be done to remove the fluid to make breathing easier.

Liver

There are a variety of ways to treat liver metastases depending on the type and extent of the primary cancer as well as the number and size of the liver metastases. In many cases, liver metastases will be treated in the same manner (with the same drugs) as the primary cancer.

Prognosis

In some situations, metastatic cancer can be cured, but most commonly, treatment does not cure metastatic cancer. However, it is possible to live for months or years with certain types of cancer, even after the development of metastatic disease.

Sometimes treatment may not be able to control the spread of cancer, or you may not be well enough to have treatment. You will still have options to manage any symptoms. This is called supportive or palliative care. Palliative care is care that makes patients feel better but doesn't treat the disease itself. 

If you have been told your cancer can no longer be controlled, you and your loved ones may want to discuss end-of-life care. 

Patients do not have to be in a hospital to receive end-of-life care. Instead, this can be given at home and nursing facilities in addition to hospitals. Hospice care is one model of end-of-life care.

Coping

Coping with emotions and lifestyle challenges is an important part of living with metastatic cancer. Ways of coping include:

  • Learning about metastasis: You might want to know everything possible, or just basic information.
  • Speaking with someone: Talking with a mental health professional about your situation.
  • Managing stress: From planning ahead to trying meditation and yoga, there are many options to help lower your stress level.
  • Finding meaning: Talking with a hospital chaplain, a counselor, or your religious leader may help.

A Word From Verywell

In some situations, metastatic cancer can be cured, but most commonly, treatment does not cure the cancer. But doctors can treat it to slow its growth and reduce symptoms.

It is important to ask your doctor about the goals of treatment. These goals may change during your care, depending on whether the cancer responds to the treatment. It is also important to know that side effects of cancer and its treatment can be managed with the help of your health care team. 

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