What Is Stage 4 Cancer?

Stage 4 cancer is the most advanced stage, meaning cancer has spread to other parts of the body. You may be able to live for years with stage 4 cancer, but the prognosis often isn't good. Rather than focusing on curing the cancer, treatments work to slow or stop growth, relieve symptoms, and help you live longer and enjoy a high quality of life.

When cancer spreads to organs away from the original tumor site, it's said to metastasize. That's why stage 4 cancer is also called metastatic cancer.

This article gives an overview of stage 4 cancer. It explains what it is, how it's diagnosed, possible treatment options, and what you should know about survival rates. 

Stage 4 Cancer Symptoms

The symptoms of metastatic cancer depend on the type of cancer and, more importantly, where the metastases have occurred. In some cases, there are no symptoms at all, so it's possible to have stage 4 cancer and not know it.

Most of the time, a cancer that reaches stage 4 affects not only the part of the body where it originated but the areas where it has spread to as well.

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 everyday things. They may even need help with getting dressed or other routine tasks.

Causes

Cancer diagnosed as stage 4 has spread to an organ or a part of the body away from the original tumor. For this to happen:

• Cancer cells break away from the tumor. They find their way into the bloodstream or, less often, the lymphatic system—a network that helps transport white blood cells and clear harmful substances from your system.
• Cells are carried in the blood or lymph fluid to another part of the body. They attach to the tissue there.
• Once they're attached, the cells grow while simultaneously fighting off the immune system.

The cancer's spread will often begin in the same region where the original cells were found. For example, breast cancer may spread to lymph nodes under the arm.

Common ways that cancer metastasizes include:

• Lung cancer to adrenal glands, bones, brain, liver, and the other lung
• Breast cancer to bones, brain, liver, and lungs
• Prostate cancer to adrenal glands, bone, liver, and lungs
• Colorectal cancer to liver, lungs, and peritoneum (lining of the abdomen)
• Melanoma to bones, brain, liver, lung, skin, and muscle

Diagnosing Stage 4 Cancer

Oncologists are doctors who specialize in diagnosing and treating cancer. Many of the same tests and procedures used to diagnose earlier stage cancers can be used to diagnose stage 4 cancer.

Biopsy

A small amount of tissue from the suspected area of spread is removed. This could be something like breast tissue, skin, or even bone marrow.

It is examined under a microscope for signs of abnormal cells.

Imaging Tests

Images make it possible to view the inside of the body to check a tumor. They help to identify where it is, how large it is, and how it's affecting other organs and blood flow.

Tests used to diagnose cancer include:

• X-rays
• Computerized tomography (CT) scan
• Magnetic resonance imaging (MRI)
• Ultrasound
• Positron emission tomography (PET) scan

Lab Tests

Many tests that are run to analyze blood, other body fluids, and biopsied tissues can be used to diagnose cancer.

Endoscopy

Endoscopy is a procedure in which a tube or wire with a small camera attached is used to look at and take pictures of internal organs.

This procedure can also help guide a practitioner as they perform a biopsy.

Cancer Staging

Stage 4 cancer is the most advanced stage of cancer based on what is known as the TNM system in which aspects of the cancer are graded on a numerical scale. The letters T, N, and M refer to specific features of a 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. These are scored from 0 to 3.
• M stands for metastasis. There are two M stages: M0 means there's no spread, while M1 means cancer cells have metastasized.

Taken together, the TNM score will help you and your healthcare team to understand how the cancer has progressed and what treatment options are available.

Substages

Some stage 4 cancers have sub-stages. For example, stage 4 prostate cancer may be labeled as stage 4A. This means it has spread to lymph nodes near the site.

Stage 4B means the spread is farther away, and the cancer may have reached bones or distant lymph nodes.

Treatment

Stage 4 cancer usually can't be cured. In addition, because it's usually spread throughout the body by the time it's diagnosed, it is unlikely the cancer can be completely removed.

The goal of treatment is to prolong survival and improve your quality of life.

An oncologist will treat the cancer depending on its type, where it has spread, and other factors. Some of the options include surgery, medication (targeted therapy), immunotherapy, and chemotherapy.

Surgery

Surgery typically is not used to treat stage 4 cancer. However, if the sites of spread are small and there aren't very many of them, they can be removed along with the primary tumor. In these instances, surgery may relieve symptoms and help prevent the cancer from spreading even more.

Targeted Therapy

Some cancer cells can be treated with medications that target specific proteins or genetic mutations.

These drugs work in different ways. For example, some help starve a tumor of its blood supply, while others block signals that prompt cancer cells to divide.

Testing can determine whether your tumor could respond to any of the available targeted therapy drugs.

Immunotherapy

Immunotherapy relies on drugs that use your immune system, including blood proteins called antibodies, to attack tumor cells.

Immunotherapy drugs exist for many types of cancer, including bladder, breast, colon and rectum, kidney, liver, lung, and blood (leukemia, lymphoma, and multiple myeloma).

Palliative Care

Stage 4 cancer treatment often includes palliative care. The goal of palliative care is to improve quality of life and increase comfort. It is provided by a team of healthcare providers and social workers who work with seriously ill patients.

It is not hospice or end-of-life care. Rather, palliative care is designed to relieve pain, ease stress, and help a person with advanced cancer to cope with symptoms.

Palliative care may be used in stage 4 cancer pain management. One example might be the use of radiation therapy to shrink a tumor that's causing pain or interfering with body functions.

This type of care may also include counseling to help people manage mental and emotional issues that arise with chronic or life-threatening illnesses.

Stage 4 Prognosis

In many cases, stage 4 cancer can't be cured. However, this is not true of all cancers. Stage 4 testicular cancer, for example, is highly curable. Lymphomas are highly curable regardless of stage.

How stage 4 cancer is likely to progress (its prognosis) depends on the type of cancer.

Some advanced cancers are very aggressive and fast-growing. Some may have fewer treatment options than others. The outlook for these cases is not likely to be positive.

However, remember that even when stage 4 cancer can't be cured, it isn't necessarily terminal—in other words, it doesn't necessarily mean that the end of life is near.

Survival Rates

One aspect of the prognosis for cancer is called relative survival rate. This refers to the overall percentage of people with a certain diagnosis who are likely to live a specific amount of time. This can be further broken down by stages of cancer.

The rates for advanced cancers are based on statistics published in the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program database.

SEER does not use TNM to classify cancers. Instead, it uses three stages—localized, regional, and distant—with "distant" generally meaning the same thing as stage 4. It refers to cancer that has spread far beyond the original site.

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 that uses a scale of 0 to 5.

Remission

It doesn't happen often, but some cancers can go into remission even if they are stage 4. Breast cancer is one such example.

Remission is when the signs and symptoms of cancer have gone away to the point where doctors declare the patient has been successfully treated.

Remission rates for stage 4 cancer vary. Even if a stage 4 cancer patient goes into remission, the cancer will probably come back. In cases like these, the stage 4 remission may instead be termed no evidence of disease (NED).

Summary

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

Symptoms of stage 4 cancer mainly depend on which organs are affected, though there may be no symptoms at all.

The prognosis for stage 4 cancer, often described in terms of survival rate, typically is not good. However, it does vary among different types of cancer. The treatment goal is not to cure stage 4 cancer, but to ease symptoms, improve quality of life, and try to keep it from progressing.

Survival rates for some cancers are low, but they are improving. For instance, compared to breast cancer average life expectancy statistics of the 1980s, those after 2010 nearly doubled. With next-generation targeted therapies and immunotherapies, those gains are likely to continue.