What Is Stage 4 Cancer?

Stage 4 cancer is the most advanced stage of cancer. It is diagnosed when cancer cells spread, or metastasize, to a part of the body far from the original tumor.

Although stage 4 cancer patients can live for years, the prognosis often isn't good. Therefore, the goal of treatment is not to cure the cancer but to stop it from growing or at least slow it down, relieve symptoms, and prolong survival.

This overview of stage 4 cancer explains what stage 4 cancer is, what metastasis means, and the specifics of diagnosis, treatment, and outcomes. 

Stage 4 Cancer Symptoms

The symptoms of metastatic cancer depend on the type of cancer. In some cases, there are no symptoms at all. Most of the time, however, once a cancer reaches stage 4 it will effect the parts of the body it has spread to.

Stage 4 cancer also can cause more general symptoms, such as extreme fatigue and lack of energy. Some people become so tired and weak they have trouble doing normal things and may even need help with tasks such as getting dressed.

Cause

Cancer diagnosed as stage 4 will have spread to an organ or a part of the body that's far from the original tumor. For this to happen:

• Cancer cells break away from the tumor and find their way into the bloodstream or, less often, the lymph system.
• Cells are carried in the blood or lymph fluid to another part of the body, where they attach to the tissue there.
• Once they're attached, the cells grow while at the same time fighting off the immune system.

This process explains what can cause a particular type of cancer to spread to a particular part of the body. Since the cells will be flowing along with the blood or lymph fluid, they are likely to land in whichever organ is next along the route.

For example, breast cancer may spread to lymph nodes under the arm but aren't likely to reach lymph nodes that are farther away. Similarly, since blood always travels through the lungs, many cancers spread to the lungs.

Common sites of cancer metastasis include:

• Breast cancer: Bones, brain, liver, and lungs
• Lung cancer: Adrenal glands, bones, brain, liver, and the other lung
• Prostate cancer: Adrenal glands, bone, liver, and lungs
• Colorectal cancer: Liver, lungs, and peritoneum
• Melanoma: Bones, brain, liver, lung, skin, and muscle

Stage 4 cancer is diagnosed based on where the original cancer is located, not where it has spread. For example, breast cancer that has spread to the liver will be called stage 4 breast cancer with liver metastasis, not stage 4 liver cancer.

Diagnosis

Oncologists, doctors who specialize in cancer, can use many of the same tests and procedure to diagnose stage 4 cancer as they do to diagnose earlier stages:

• Biopsy: A small amount of tissue is removed and examined under a microscope for signs of abnormal cells. Tissue samples can come from anywhere on the body, such as the skin, bone marrow, or breast.
• Imaging tests: Techniques that make it possible to look inside the body in order to see where a tumor might be, how large it is, and how it affects other organs and blood flow. Imaging tests for diagnosing cancer include X-rays, computerized tomography (CT) scans, magnetic resonance imaging (MRI), ultrasound, and positron emission tomography (PET) scans.
• Lab tests: Many tests that involve analyzing blood, other body fluids, and biopsied tissues can be done to diagnose cancer.
• Endoscopy: A procedure in which a tube or wire with a small camera attached is used to look at internal organs, take pictures, and help with taking a biopsy sample.

Staging

Stage 4 cancer is the most advanced stage of cancer based on what is known as the TNM system. Each of the letters refer to specific aspects of a particular cancer:

• T refers to the size of the tumor. and whether it has spread to nearby tissue or organs. The T rating ranges from 0 to 4.
• N refers to whether the cancer has spread to lymph nodes. It's based on a range of 0 to 3.
• M stands for metastasis. There are two M stages—0, which means there's no spread, and 1, which means cancer cells have metastasized.

Some stage 4 cancers have sub-stages. For example, stage 4 prostate cancer may be labeled as stage 4A, meaning it has spread to local (also called regional) lymph nodes; and stage 4B, in which spread is more distant and could include metastases in the bones or farther-flung lymph nodes.

Treatment

Stage 4 cancer usually can't be cured. Because it will have spread throughout the body, it is unlikely it can be completely remove it and so the goal of treatment is to prolong survival and improve quality of life. The measures an oncologist will take will depend on the type of cancer, where it has spread, and other factors, including:

Surgery: Surgery typically is not used to treat stage 4 cancer. However, if the metastases are small and there aren't many of them, removing them along with the primary tumor may relieve symptoms, help prevent the cancer from spreading further, and prolong life.

Hyperthermic Intraperitoneal Chemotherapy (HIPEC): This is procedure sometimes used after surgery for stage 4 cancer that has spread to the lining of the abdomen. It involves using a heated chemotherapy solution to bathe the lining. HIPEC has been found to increase disease-free survival and extend life by as much as 60%.

Targeted Therapy: Some cancer cells can be treated with medications that target specific proteins or genetic mutations. For example, targeted drugs have been shown to double survival times for people with chronic myeloid leukemia.

Immunotherapy: This treatment involves medications that use antibodies or the patient’s own immune system to attack tumor cells. There are immunotherapies for many types of cancer, including bladder, breast, brain, cervical, colon and rectum, esophagus, head and neck, kidney, liver, lung, ovaries, pancreas, prostate, skin, stomach, uterus, and blood (leukemia, lymphoma, and multiple myeloma).

Palliative Care

The goal of palliative care for stage 4 cancer is to improve quality of life. It is provided by a team of doctors, nurses, and social workers who specialize in working with seriously ill patients.

It is not hospice or end-of-life care. Rather, palliative care treatments are designed relieve pain, ease stress, and help a person with advanced cancer feel as comfortable as possible.

These treatments range from radiation therapy to shrink a tumor that is causing pain or interfering with how well the body functions to therapy or counseling to help managin mental and emotional issues that are inevitable with chronic or life-threatening illness.

Prognosis

In most cases, the prognosis—how the disease is likely to progress—for stage 4 cancer depends on the type of cancer. Some advanced cancers are more aggressive or have fewer treatment options than others, for example, and so are not likely to have a positive prognosis.

One aspect of the prognosis for advanced cancer is relative survival rate, which refers to the percentage of people with a particular diagnosis likely to live a specific amount of time. The relative survival rates for advanced cancer are based on statistics published in the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program database.

For most types of cancer, SEER lists uses five years to express survival rates.

Other factors that affect the prognosis for stage 4 cancer include age, overall health, smoking history, and performance status (PS). PS is how well a person is able to perform everyday tasks. It's based on a classification system from the Eastern Cooperative Oncology Group (ECOG) that uses a scale of 0 to 5.

Some stage 4 cancers (like breast cancer) can go into remission. Remission is when the signs and symptoms of cancer have gone away to the point where doctors declare the patient successfully treated.

Like survival rates, remission rates for stage 4 cancer vary, but remission is not common. Even if a stage 4 cancer patient goes into remission, the cancer will probably come back. In cases like these, doctors prefer to describe stage 4 remission as no evidence of disease (NED).

Summary

Stage 4 cancer, sometimes called advanced cancer or late-stage cancer, is cancer that has metastasized (spread) to a part of the body for from the original tumor. This occurs when cancer cells break away from the original tumor and enter the bloodstream or lymphatic system.

Symptoms of stage 4 cancer mainly depend on which organs are affected, although many people with stage 4 cancer have general symptoms such as extreme fatigue. The prognosis for stage 4 cancer, which often is expressed in terms of survival rate, typically is not good, but varies widely among different types of cancer. The goal of treatment is not to cure stage 4 cancer, but to try to keep it from progressing, ease symptoms, improve quality of life, and extend survival.

A Word From Verywell

Survival rates for some cancers are low, they are ever-improving, and doctors and researchers are continually discovering and testing new targeted drugs and immunotherapies. They may be far different in the near future than they are today.

For example, during the 1980s to 1990s, survival rates in women with breast cancer barely budged. But between 1990 and 2010, they changed dramatically: average life expectancy nearly doubled from 32 months to 57 months. With rapid advances in next-generation targeted therapies and immunotherapies, those gains are likely to continue.