What Is Stage 4 Cancer?

Doctors deliver a cancer diagnosis with a description of the disease’s stage and level of metastasis. Stage 4 cancer, also known as metastatic cancer, is the most advanced stage. It is the least likely to be cured and is unlikely to end up in remission. 

That doesn’t mean it’s automatically a death sentence—many stage 4 cancer patients live for many years—but the prognosis is not likely to be good. The disease’s course can vary significantly by the cancer type, its genetic makeup, the extent of metastasis, and other factors—including the patient’s general health and wellness. 

This stage 4 cancer overview will help you understand what this diagnosis means for you or your loved one. Read on for more specific details about what stage 4 cancer is, what metastasis means, and the specifics of diagnosis, treatment, and outcomes. 

Definition

A stage 4 cancer diagnosis means that cancer has metastasized. Metastasis is the spread of cancer cells beyond the original tumor to other organs and the body’s lymph nodes.

Lymph nodes are small tissues spread throughout the body that filter and hold white blood cells, the body’s immune cells. They’re linked by a network of vessels (the lymphatic system) that connects to the blood vessels to make up the circulatory system.

Cancerous tumors are clumps of the body’s cells that have grown uncontrollably because of changes in their genes. They act differently than healthy cells, and sometimes some will detach from the tumor, push through the walls of the tissues, and escape into the bloodstream.

These escapees use the blood and lymph vessels to travel to the lymph nodes, where they can burrow into the tissue and set up shop and grow into a new mass. Cells can then escape these masses, jump back into the lymph system and blood vessels, and restart the process—continuing to spread to other lymph nodes and even solid organs. 

Understanding and evaluating cancer’s spread is the basis on which researchers established the TNM—tumor, nodes, and metastasis—classification system to identify, group, and be able to compare the extent to which cancer has grown in any patient and between patients.

For anyone who has been or has had a loved one diagnosed with stage 4 cancer, understanding the stages of cancer, what they mean, and how stage 4 compares to other cancer stages is extremely important. Staging affects patients’ survival rates, treatment options, eligibility for clinical trials, and remission potential.

TNM Classification

Doctors use a classification system developed by the American Joint Committee on Cancer, called the TNM system, to assess a patient’s cancer stage. While the actual breakdown of letters and numbers differs depending on cancer location, the stages have the same three components:

• T in the classification defines the tumor itself. The T rating ranges from 0 to 4 based on the mass’s size and its spread into the tissue or surrounding organs. The patient’s prognosis is worse if the tumor is bigger and has spread.
• N defines the spread to the lymph nodes. The N classification runs from 0 to 3. Lymph nodes are important for cancer prognosis, because spread there makes it easier for the cancer to move on to other parts of the body. The further the spread, the higher the N classification number.
• M stands for metastasis, the spread of cancer to far-flung parts of the body. There are only two M stages—0 or 1. Metastasis to other solid organs means a worse prognosis, since there are more places for the cancer cells to hide from treatment.

An M score of 1 automatically classifies cancer as stage 4, but the T and N classifications also factor into the overall prognosis.

Some cancers have sub-stages within stage 4, typically labeled stage 4A and stage 4B.  For example, stage 4 prostate cancer includes stage 4A, in which cancer 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.

Cancers from one location metastasize in similar ways. Here are some examples of common cancers and where their stage 4 malignancies are commonly found.

• 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.

Other Classification Systems

Some cancers have specialized staging systems instead of, or alongside, the TNM staging. Some use the familiar stage 1 through 4 ratings, but others use different labeling systems. 

Cervical cancers use a system from the International Federation of Gynecologists and Obstetricians. Blood cancers use the Lugano staging system or, for chronic lymphocytic leukemia, the Rai staging system.

Some more unique cancers also have unique rating systems. Small-cell lung cancers are “limited” or “extensive” based on how far they've spread. The Binet staging system used for chronic lymphocytic leukemia, has three stages: A, B, and C.

Cancers of the brain and central nervous system rarely spread beyond those organs, so they don’t have a formal staging system—instead, doctors use grades to classify tumors.

Grading a Tumor

Another term you might hear is the tumor’s grade—the grade factors into the cancer’s diagnosis, treatment, and staging. After surgery or a biopsy, the doctors will examine the cancerous cells and tissues in the lab and give them a grade by comparing how they look to normal cells.

From this information, the cancer cells get one of three grades: Grade 1 (low grade), grade 2 (intermediate grade), or grade 3 (high grade). A higher-stage cancer is usually also a higher-grade cancer.

If a tumor is low-grade, its cells usually look relatively normal or well-differentiated, and they are typically slower-growing. A high-grade tumor is likely to be more aggressive, look less like a normal cell, and spread quickly. Doctors call these undifferentiated or poorly differentiated tumor cells because they lack the features and structures of normal cells and tissues.

Diagnosis

Staging begins when the cancer is officially diagnosed. The patient will probably undergo many tests and procedures during the staging process. These will vary by type of tumor, and they won’t all apply for every cancer. 

There are several standard types of tests that are common when diagnosing and staging cancers:

• A biopsy is when a doctor cuts off a small piece of the potential tumor. They then look at it under the microscope to determine if it’s cancerous and, if so, give it a grade. These tissue samples can be from anywhere on the body, such as the skin, bone marrow, or breast.
• Imaging tests, like X-ray, CT, MRI, ultrasound, and PET scans, peer inside the body to visualize a tumor and determine how it affects other organs and blood flow. Without cutting a patient open, these images give the doctor a better idea of a cancer’s size and makeup.
• Lab tests analyze the proteins and other molecules found in the patient’s blood, bodily fluids, or biopsied tissue samples. Tumor markers and genetic screening of tumor samples can help doctors choose the best treatments, and general blood testing helps monitor the patient’s all-around health.  
• Endoscopy uses a tube or wire with a small camera to visualize the internal organs—for example, a colonoscopy, bronchoscopy, or laparoscopy. The doctors will use the tube to take pictures and even biopsy a sample. 

Treatment

A stage 4 cancer diagnosis usually means that the cancer is incurable. In most cases, treatment aims to prolong survival and improve quality of life. Because the cancer has spread throughout the body, it is extremely unlikely that doctors can eradicate it, even with a combination of surgery, chemotherapy, and radiation. 

With rare exceptions, surgery is not a part of stage 4 cancer treatment. That doesn't mean that surgery is entirely out of the question—if the metastases are small and few, surgeons may remove them along with the primary tumor to prolong life and slow the disease’s progression. 

Sometimes, surgery followed by a procedure called hyperthermic intraperitoneal chemotherapy (HIPEC) may increase survival times and disease-free survival by as much as 60%. In this procedure—used when tumors have spread to the abdomen’s lining only—doctors will bathe the body’s core in a heated chemotherapy solution to fight back metastases.

Similarly, newer targeted therapies and immunotherapies can slow stage 4 disease progression when conventional drug therapies no longer work. With advanced genomic testing and immunostaining, doctors can now determine if cancer cells with specific proteins or genetic mutations are “treatable” with targeted drugs, with some able to double survival times in people with diseases like chronic myeloid leukemia.

Today, doctors can treat stage 4 cancers of many kinds with immunotherapeutic drugs, which use antibodies or the patient’s own immune system to attack tumor cells. Immunotherapies exist that can target cancer of the 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).

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).

Palliative Care

One thing that can help patients is a palliative care team. If treatments that might cure the cancer aren’t available, many therapies can improve quality of life. This is called palliative care. These specialized doctors, nurses, and social workers work with seriously ill patients to relieve symptoms and treatment side effects.

It does not mean hospice or end-of-life care; instead, these treatments help improve patients’ stress levels, pain, and discomfort. Beyond caring for the patient’s mental health and making them comfortable, palliative care may include radiation therapy to reduce tumor size and symptoms.

No matter what cancer stage, palliative care can help—it is a treatment modality applied to both life-limiting and non-life-limiting conditions.

Prognosis

The prognosis of stage 4 cancer can vary dramatically by the type of cancer. Some stage 4 cancers are more aggressive or have fewer treatment options, while others may be less aggressive and have more treatment options.

For example, nearly 89% of people with stage 4 thyroid cancer live for at least five years, with many living 10 years or more. On the other hand, only around 8% of people with stage 4 mesothelioma will survive for five years or more.

Survival rates help doctors estimate how long a person with a specific diagnosis will survive. The cancer-specific survival rate is the portion of people with a particular diagnosis that survived until a set time. Doctors usually talk about survival in a five-year time frame, but you’ll also hear one-year, two-year, and 10-year survival rates.

The National Cancer Institute has been collecting and publishing cancer statistics from 19 states in their Surveillance, Epidemiology, and End Results (SEER) Program database. The SEER database does not use the TNM staging system. Cancer registries like SEER typically use a three-stage approach:

• Localized cancers are only in the area in which they first developed. 
• Regional cancers have spread to nearby lymph nodes, tissues, or organs.
• Distant cancers have metastasized to remote parts of the body—these are stage 4 cancers.

The figures below show relative survival rates from the NCI’s SEER database, which monitors cancer incidence and outcomes. The numbers below for the top 12 cancers are the five-year survival rates (relative to similar people without cancer) for a “distant” diagnosis, between the years 2010 and 2016.

The exceptions are for lymphoma and leukemia, which doctors stage differently. The Non-Hodgkin lymphoma number is the stage IV survival, and the leukemia is the overall five-year relative survival rate (at any stage). 

As you can see, survival rates vary widely by cancer type, grade, genetics, and other traits. A patient’s performance status (PS) also plays a significant role in prognosis and outcomes.

The PS score is a way to define a patient’s ability to perform everyday tasks and uses a classification scale from the Eastern Cooperative Oncology Group (ECOG) of 0 to 5. Other traits—including age, general health, and if the patient is an active or previous smoker—can also affect prognosis.

Can the Cancer Stage Change?

Once diagnosed, a cancer’s stage never changes. Even if the patient improves or gets worse, their cancer is the same as when diagnosed. 

Part of the reason for this is statistical—stages help scientists track and reevaluate survival statistics and treatment protocols.  But they also let doctors track the efficacy of treatments for your stage.

Doctors use cancer stages to compare patients with similar diagnoses, to more easily study the effectiveness of treatments, to track a person’s cancer progression, and as a way to estimate survival rates for specific cancers. 

Part of the confusion regarding staging status arises from the fact the disease is sometimes re-staged. Re-staging determines if there has been a progression or remission of the disease.

If cancer is re-staged or recurs (marked with an r), doctors keep the initial staging diagnosis and add a new stage to the patient’s diagnosis. New staging diagnoses get differentiated with letters—like c for clinical, p for pathological (after surgery), or y for after treatment.

For instance, stage 2 breast cancer that suddenly spreads to the lungs is “stage 2 breast cancer with lung metastases” rather than stage 4 breast cancer. Similarly, if stage 4 breast cancer meets the definition of remission after treatment, they describe it as “stage 4 breast cancer with no evidence of disease.”

The only exception to this rule is when a patient develops a second primary cancer (one that’s not derived from the first cancer). In this case, the new tumor would be staged and graded separately from the first. Doctors would also compare the cancers’ genes to determine if they’re related.

A Word From Verywell

A cancer diagnosis is a life-changing event, especially when the diagnosis is later-stage cancer. However, stage 4 cancer isn’t a death sentence.

Though 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.