- Staging Groups
- Cancer Staging
- Why is staging needed?
- What is the doctor looking for when staging cancer?
- How are cancers staged?
- Staging systems
- A cancer’s stage does not change
- Finding out more about your type of cancer
- Cancer stages
- Stages of cancer
- What cancer staging is
- Why staging is important
- Cancer spread in the lymph nodes
- Adjuvant treatment
- Types of staging systems
- The TNM staging system
- Number staging systems
- Carcinoma in situ
- Related information
- Cancer Staging
- Key Points
- What is staging?
- What are the common elements of staging systems?
- How does tumor size relate to breast cancer stage?
Your doctor will use information from test results (clinical stage) or possibly the tumor itself (pathologic stage) to decide your overall stage.
Most cancers that involve a tumor are staged in five broad groups. These are usually referred to with Roman numerals. Other kinds, like blood cancers, lymphoma, and brain cancer, have their own staging systems. But they all tell you how advanced the cancer is.
- Stage 0 means there’s no cancer, only abnormal cells with the potential to become cancer. This is also called carcinoma in situ.
- Stage I means the cancer is small and only in one area. This is also called early-stage cancer.
- Stage II and III mean the cancer is larger and has grown into nearby tissues or lymph nodes.
- Stage IV means the cancer has spread to other parts of your body. It’s also called advanced or metastatic cancer.
A physical exam and several tests are used to determine your clinical stage — an estimate of how far the cancer has spread. Tests may include blood and other lab tests and imaging scans. Those may be X-rays or any of the following:
- Magnetic resonance imaging (MRI): Powerful magnets and radio waves are used to make detailed images of the affected area.
- Computerized tomography (CT) scan: Several X-rays are taken from different angles and put together to show more information.
- Ultrasound: High-frequency sound waves are used to make images of the inside of your body.
You also may have a biopsy, in which a small piece of tissue is taken and looked at under a microscope.
If a tumor is removed with surgery, your doctor will learn more about it and how it’s affected your body. That information is added to your test results to determine the pathologic stage, or surgical stage. This can be different from the clinical stage, and it’s considered more accurate.
Staging is the process of finding out how much cancer is in a person’s body and where it’s located. It’s how the doctor determines the stage of a person’s cancer.
For most types of cancer, doctors use staging information to help plan treatment and to predict a person’s outlook (prognosis). Although each person’s situation is different, cancers with the same stage tend to have similar outlooks and are often treated the same way. The cancer stage is also a way for doctors to describe the extent of the cancer when they talk with each other about a person’s cancer.
Why is staging needed?
Doctors need to know the amount of cancer and where it is in the body to be able to choose the best treatment options. For example, the treatment for an early-stage cancer may be surgery or radiation, while a more advanced-stage cancer may need to be treated with chemotherapy. Doctors also use a cancer’s stage to help predict the course it will likely take.
In a larger sense, doctors use staging information when they’re studying cancer treatments. It allows researchers to make sure study groups are actually similar when they test cancer treatments against one another, measure outcomes, and more.
Not all cancers are staged. For example, leukemias are cancers of the blood cells and therefore spread throughout the body. Most types of leukemias aren’t staged the way cancers that form tumors are.
What is the doctor looking for when staging cancer?
When trying to determine the extent of the cancer in the body, doctors first look at the primary (main) tumor for its size, location, and whether it has grown into nearby areas. Doctors also check for other nearby tumors.
Doctors might also look at nearby lymph nodes to find out if cancer has spread into them. Lymph nodes are small, bean-shaped collections of immune cells. Many types of cancer often spread to nearby lymph nodes before they reach other parts of the body.
Doctors might also look at other parts of the body to see if the cancer has spread there. When cancer spreads to parts of the body far from the primary tumor, it is known as metastasis.
In some kinds of cancer, other factors are also used to help determine the stage, such as the cancer cell type and grade (how abnormal the cancer cells look under a microscope), or the results of certain blood tests.
How are cancers staged?
Doctors use different types of exams and tests to figure out a cancer’s stage. Depending on where the cancer is located, the physical exam may give some clue as to how much cancer there is. Imaging tests like x-rays, CT scans, MRIs, ultrasound, and PET scans may also give information about how much and where cancer is in the body.
A biopsy often is needed to confirm a cancer diagnosis. Biopsies might also be needed to find out if an abnormal spot seen on an imaging test is really cancer spread. During a biopsy, the doctor removes a tumor or pieces of a tumor to be looked at under a microscope. Some biopsies are done during surgery. But with many types of biopsies, the doctor removes small pieces of tumor through a thin needle or through a flexible lighted tube called an endoscope. The different kinds of biopsies used to check for cancer are described in Cancer Surgery.
Types of staging
Staging is done when a person is first diagnosed, before any treatment is given. The main types of staging are:
This is an estimate of the extent of the cancer based on results of physical exams, imaging tests (x-rays, CT scans, etc.), and tumor biopsies. For some cancers, the results of other tests, such as blood tests, are also used in staging.
The clinical stage is a key part of deciding the best treatment to use. It’s also the baseline used for comparison when looking at how the cancer responds to treatment.
If surgery is being done, doctors can also determine the pathologic stage (also called the surgical stage) of the cancer. The pathologic stage relies on the results of the exams and tests mentioned before, as well as what is learned about the cancer during surgery. Often this is surgery to remove the cancer and nearby lymph nodes, but sometimes surgery may be done to just look at how much cancer is in the body and take out tissue samples.
Sometimes, the pathologic stage is different from the clinical stage (for instance, if the surgery shows the cancer has spread more than was thought). The pathologic stage gives the health care team more precise information that can be used to predict treatment response and outcomes (prognosis).
There are different types of staging systems, but the most common and useful staging system for most types of cancers is the TNM system.
The TNM system
The American Joint Committee on Cancer (AJCC) and the International Union for Cancer Control (UICC) maintain the TNM classification system as a tool for doctors to stage different types of cancer based on certain standards. It’s updated every 6 to 8 years to include advances in our understanding of cancer.
In the TNM system, each cancer is assigned a letter or number to describe the tumor, node, and metastases.
- T stands for the original (primary) tumor.
- N stands for nodes. It tells whether the cancer has spread to the nearby lymph nodes
- M stands for metastasis. It tells whether the cancer has spread to distant parts of the body
- TX means the tumor can’t be measured.
- T0 means there is no evidence of a primary tumor (it cannot be found).
- Tis means that the cancer cells are only growing in the most superficial layer of tissue, without growing into deeper tissues. This may also be called in situ cancer or pre-cancer.
- Numbers after the T (such as T1, T2, T3, and T4) might describe the tumor size and/or amount of spread into nearby structures. The higher the T number, the larger the tumor and/or the more it has grown into nearby tissues.
The T category gives information about aspects of the original (primary) tumor, such as its size, how deeply it has grown into the organ it started in, and whether it has grown into nearby tissues.
The N category describes whether the cancer has spread into nearby lymph nodes.
- NX means the nearby lymph nodes cannot be evaluated.
- N0 means nearby lymph nodes do not contain cancer.
- Numbers after the N (such as N1, N2, and N3) might describe the size, location, and/or the number of nearby lymph nodes affected by cancer. The higher the N number, the greater the cancer spread to nearby lymph nodes.
The M category tells whether the cancer has spread (metastasized) to distant parts of body).
- M0 means that no distant cancer spread was found.
- M1 means that the cancer has spread to distant organs or tissues (distant metastases were found).
Most cancer types have their own version of this classification system, so letters and numbers don’t always mean the same thing for every kind of cancer. For example, in some types of cancer, the T categories describe the size of the main tumor, while in others they describe how deeply the tumor has grown in to the organ it started in, or whether the tumor has grown into nearby structures (regardless of its size).
Some cancer types also have special groupings that are different from other cancer types. For instance, for some cancers, classifications may have subcategories, such as T3a and T3b, while others may not have an N3 category.
Once the values for T, N, and M have been determined, they are combined to assign an overall stage. For most cancers, the stage is a Roman numeral from I to IV, where stage IV (4) is the highest and means the cancer is more advanced than in the lower stages. Sometimes stages are subdivided as well, using letters such as A and B.
Stage 0 is carcinoma in situ for most cancers. This means the cancer is at a very early stage, is only in the area where it first developed, and has not spread. Not all cancers have a stage 0.
Stage I cancers are the next least advanced and often have a good prognosis (outlook). The outlook is usually not as good for higher stages.
Other factors that can affect the stage
For some cancers, the values for T, N, and M aren’t the only things that determine the stage. Some other factors that may be taken into account include:
Grade: For most cancers, the grade is a measure of how abnormal the cancer cells look under the microscope. This is called differentiation. Grade can be important because cancers with more abnormal-looking cells tend to grow and spread faster.
The grade is usually assigned a number. In low-grade (well-differentiated) cancers, the cancer cells look a lot like cells from normal tissue. In general, these cancers tend to grow slowly. In high-grade (poorly differentiated) cancers, the cancer cells look very different from normal cells. High-grade cancers often tend to grow quickly and have a worse outlook, so they may need different treatments than low-grade cancers. Even when the grade doesn’t affect a cancer’s stage, it may still affect the outlook and/or treatment.
Cell type: Some cancers can be made up of different types of cells. Because the type of cancer cell can affect treatment and outlook, it can be a factor in staging. For example, cancers of the esophagus are mainly either squamous cell cancers or adenocarcinomas. Squamous cell esophageal cancers are staged differently from esophageal adenocarcinomas.
Tumor location: For some cancers, the tumor’s location affects outlook and is taken into account in staging. The stage of cancer of the esophagus, for example, depends on whether the cancer is in the upper, middle, or lower third of the esophagus.
Tumor marker levels: For some cancers, the blood levels of certain substances (called tumor markers) can affect the stage of the cancer. For example, in prostate cancer, the level of prostate-specific antigen (PSA) in the blood is taken into account in assigning a stage.
Other staging systems
Not all cancers are staged using the TNM system. Some cancers grow and spread in a different way. For example, many cancers in or around the brain are not staged using the TNM system, since these cancers tend to spread to other parts of the brain and not to lymph nodes or other parts of the body. Staging systems other than the TNM system are often used for Hodgkin disease and other lymphomas, too, as well as for some childhood cancers.
The International Federation of Gynecologists and Obstetricians (FIGO) has a staging system for cancers of the female reproductive organs. The TNM stages closely match the FIGO stages, which makes it fairly easy to convert stages between these 2 systems.
Other, older staging systems (such as the Dukes system for colorectal cancer) may still be used by some doctors. If your doctor uses another staging system, you may want to find out if the stage can be translated into the TNM system. This will often help if you want to read more about your cancer and its treatment, since the TNM system is more widely used.
A cancer’s stage does not change
An important point some people have trouble understanding is that the stage of a cancer is determined only when (or soon after) the cancer is diagnosed. This stage does not change over time, even if the cancer shrinks, grows, spreads, or comes back after treatment. The cancer is still referred to by the stage it was given when it was first found and diagnosed, although information about the current extent of the cancer is added (and of course, the treatment is adjusted as needed).
For example, let’s say a woman is first diagnosed with stage II breast cancer. The cancer goes away with treatment, but then it comes back and has spread to the bones. The cancer is still called a stage II breast cancer, now with recurrent disease in the bones.
If the breast cancer did not go away with the original treatment and spread to the bones it would be called a stage II breast cancer with bone metastasis. In either case, the original stage does not change and it’s not called a stage IV breast cancer. Stage IV breast cancer refers to a cancer that has already spread to a distant part of the body when it’s first diagnosed.
This is important to understand because survival statistics and information on treatment by stage for specific cancer types refer to the stage when the cancer was first diagnosed. The survival statistics related to stage II breast cancer that has recurred in the bones may not be the same as the survival statistics for stage IV breast cancer.
At some point you may hear the term “restaging.” Restaging is a term sometimes used to describe doing tests to find the extent of the cancer after treatment. This is rarely done, but it may be used to measure the cancer’s response to treatment or to assess cancer that has come back (recurred) and will need more treatment. Often the same tests that were done when the cancer was first diagnosed (such as physical exams, imaging tests, biopsies, and maybe surgery) will be done again. After these tests a new stage may be assigned. It’s written with a lower-case “r” before the new stage to note that it’s different from the stage at diagnosis. The originally diagnosed stage always stays the same. While testing to see the extent of cancer is common during and after treatment, actually assigning a new stage is rarely done, except in clinical trials.
Finding out more about your type of cancer
For details on staging or grading for a certain type of cancer, see our information on specific cancer types. You can find this information on our website, or call our toll-free number.
What is stage IV cancer?
Stage IV cancer is sometimes referred to as metastatic cancer, because it often means the cancer has spread from its origin to distant parts of the body. This stage may be diagnosed years after the initial cancer diagnosis and/or after the primary cancer has been treated or removed.
When a cancer metastasizes to a different part of the body, it is still defined by its original location. For instance, if breast cancer metastasizes to the brain, it is still considered breast cancer, not brain cancer. Many stage IV cancers have subcategories, such as stage IVA or stage IVB, which are often determined by the degree to which the cancer has spread throughout the body.
Liquid cancers, or blood cancers, such as leukemia, lymphoma or multiple myeloma, are staged differently than most other cancers because they may not always form solid tumors. Liquid cancers may be staged by a variety of factors, including:
- The ratio of healthy blood cells to cancerous cells
- The degree to which lymph nodes, the liver or spleen may be swollen
- Whether the cancer has resulted in blood disorders such as anemia
Stage IV cancer is determined in the five most common cancers this way:
Stage IV breast cancer
The cancer has spread beyond the breast, underarm and internal mammary lymph nodes to other parts of the body near to or distant from the breast. Metastatic breast cancer most often spreads to the bones, brain, lungs and/or liver.
Learn more about breast cancer stages
Stage IV lung cancer
The cancer has spread beyond the lungs or from one lung to the other. Metastatic lung cancer most often spreads to the adrenal glands, bones, brain and/or liver.
Learn more about lung cancer stages
Stage IV prostate cancer
The cancer is found in other parts of the body, even after the prostate has been removed. Metastatic prostate cancer usually travels to the adrenal glands, liver, bones and/or lungs.
Learn more about prostate cancer stages
Stage IV colorectal cancer
The cancer has spread to one or more organs that are not near the colon. Metastasized colorectal cancer most commonly spreads to the liver, lungs and/or bones.
Learn more about colorectal cancer stages
Stage IV melanoma
The cancer cells have spread beyond the skin and local lymph nodes to distant lymph nodes, organs and/or other areas of skin. Metastasized melanoma may be found in the bones, brain, liver or lungs.
Learn more about melanoma stages
Most cancers are staged using some form of the TNM system. Doctors may also use the TNM system to help determine the extent of certain cancers in each stage. The TNM system stands for:
- T (tumor), or the size of the original tumor
- N (node), or whether the cancer is present in the lymph nodes
- M (metastasis), or whether the cancer has spread to other parts of the body
Some cancers, especially liquid cancers, are staged using different established protocols. The Binet and Rai systems, for instance, are used to stage certain types of leukemia.
Cancers of the central nervous system (CNS) are graded rather than staged. Grade IV brain and spinal cancers are considered very aggressive and fast-growing. Tumors that have spread to the CNS from another location in the body are much more common than primary brain or spinal column tumors.
Stages of cancer
This page tells you about the stages of a cancer. There is information about
What cancer staging is
Staging is a way of describing the size of a cancer and how far it has grown. When doctors first diagnose a cancer, they carry out tests to check how big the cancer is and whether it has spread into surrounding tissues. They also check to see whether it has spread to other parts of the body.
Cancer staging may sometimes include the grading of the cancer. This describes how similar a cancer cell is to a normal cell.
Why staging is important
Staging is important because it helps your treatment team to know which treatments you need.
Doctors may recommend a local treatment, such as surgery or radiotherapy, if your cancer is just in one place. This could be enough to get rid of the cancer completely. A local treatment treats only an area of the body.
But you may need treatment that circulates throughout the whole body if your cancer has spread. These are called systemic treatments and include:
- hormone therapy
- targeted cancer drugs
You can read more about the different types of cancer treatment.
Cancer spread in the lymph nodes
Sometimes doctors aren’t sure if a cancer has spread to another part of the body or not. So they look for cancer cells in the lymph nodes near the cancer.
Cancer cells in these nodes is a sign that the cancer has begun to spread. This is often called as having positive lymph nodes. It means that the cells have broken away from the original cancer and got trapped in the lymph nodes. But it isn’t always possible to tell if they have gone anywhere else.
Doctors usually suggest adjuvant treatment if you have cancer cells in the lymph nodes. This means having treatment in addition to the main treatment for the primary tumour. An example of this is having chemotherapy after surgery.
The aim of adjuvant treatment is to kill any cancer cells that have broken away from the primary tumour.
Types of staging systems
There are 2 main types of staging systems for cancer. These are the TNM system and the number system.
The systems mean that:
- doctors have a common language to describe the size and spread of cancers
- treatment results can be accurately compared between research studies
- different hospitals and clinics have standard treatment guidelines
Some blood cancers or lymph system cancers have their own staging systems.
The TNM staging system
TNM stands for Tumour, Node, Metastasis. This system describes the size of the initial cancer (the primary tumour), whether the cancer has spread to the lymph nodes, and whether it has spread to a different part of the body (metastasised). The system uses letters and numbers to describe the cancer:
- T refers to the size of the cancer and how far it has spread into nearby tissue – it can be 1, 2, 3 or 4, with 1 being small and 4 large
- N refers to whether the cancer has spread to the lymph nodes – it can be between 0 (no lymph nodes containing cancer cells) and 3 (lots of lymph nodes containing cancer cells)
- M refers to whether the cancer has spread to another part of the body – it can either be 0 (the cancer hasn’t spread) or 1 (the cancer has spread)
So for example, a small cancer that has spread to the lymph nodes but not to anywhere else in the body may be T2 N1 M0. Or a more advanced cancer that has spread may be T4 N3 M1.
Sometimes doctors use the letters a, b or c to further divide the categories. For example, stage M1a lung cancer is a cancer that has spread to the other lung. Stage M1b lung cancer has spread to other parts of the body.
The letter p is sometimes used before the letters TNM. For example, pT4. This stands for pathological stage. It means that doctors based the staging on examining cancer cells in the lab, after surgery to remove a cancer.
The letter c is sometimes used before the letters TNM. For example, cT2. This stands for clinical stage. It means that the stage is based on what the doctor knows about the cancer before surgery. Doctors may look at your tests results and use the clinical information from examining you.
Number staging systems
Number staging systems usually use the TNM system to divide cancers into stages. Most types of cancer have 4 stages, numbered from 1 to 4. Often doctors write the stage down in Roman numerals. So you may see stage 4 written down as stage IV.
Here is a brief summary of what the stages mean for most types of cancer:
Stage 1 usually means that a cancer is relatively small and contained within the organ it started in
Stage 2 usually means that the tumour is larger than in stage 1, but the cancer has not started to spread into the surrounding tissues. Sometimes stage 2 means that cancer cells have spread into lymph nodes close to the tumour. This depends on the particular type of cancer
Stage 3 usually means the cancer is larger. It may have started to spread into surrounding tissues and there are cancer cells in the lymph nodes in the area
Stage 4 means the cancer has spread from where it started to another body organ. This is also called secondary or metastatic cancer
Sometimes doctors use the letters A, B or C to further divide the number categories. For example, stage 3B cervical cancer.
Carcinoma in situ
Carcinoma in situ is sometimes called stage 0 cancer or ‘in situ neoplasm’. It means that there is a group of abnormal cells in an area of the body. The cells may develop into cancer at some time in the future. The changes in the cells are called dysplasia. The number of abnormal cells is too small to form a tumour.
Some doctors and researchers call these cell changes ‘precancerous changes’ or ‘non invasive cancer’. But many areas of carcinoma in situ will never develop into cancer. So some doctors feel that these terms are inaccurate and they don’t use them.
Because these areas of abnormal cells are still so small they are usually not found unless they are somewhere easy to spot, for example in the skin. A carcinoma in situ in an internal organ is usually too small to show up on a scan. But tests used in cancer screening programmes can pick up carcinomas in situ in the breast or the neck of the womb (cervix).
You can read our information about
Specific staging systems for different types of cancer
Stage refers to the extent of your cancer, such as how large the tumor is, and if it has spread. Knowing the stage of your cancer helps your doctor:
- Understand how serious your cancer is and your chances of survival
- Plan the best treatment for you
- Identify clinical trials that may be treatment options for you
A cancer is always referred to by the stage it was given at diagnosis, even if it gets worse or spreads. New information about how a cancer has changed over time gets added on to the original stage. So, the stage doesn’t change, even though the cancer might.
How Stage Is Determined
To learn the stage of your disease, your doctor may order x-rays, lab tests, and other tests or procedures. See the section on Diagnosis to learn more about these tests.
Systems that Describe Stage
There are many staging systems. Some, such as the TNM staging system, are used for many types of cancer. Others are specific to a particular type of cancer. Most staging systems include information about:
- Where the tumor is located in the body
- The cell type (such as, adenocarcinoma or squamous cell carcinoma)
- The size of the tumor
- Whether the cancer has spread to nearby lymph nodes
- Whether the cancer has spread to a different part of the body
- Tumor grade, which refers to how abnormal the cancer cells look and how likely the tumor is to grow and spread
The TNM Staging System
The TNM system is the most widely used cancer staging system. Most hospitals and medical centers use the TNM system as their main method for cancer reporting. You are likely to see your cancer described by this staging system in your pathology report, unless you have a cancer for which a different staging system is used. Examples of cancers with different staging systems include brain and spinal cord tumors and blood cancers.
In the TNM system:
- The T refers to the size and extent of the main tumor. The main tumor is usually called the primary tumor.
- The N refers to the the number of nearby lymph nodes that have cancer.
- The M refers to whether the cancer has metastasized. This means that the cancer has spread from the primary tumor to other parts of the body.
When your cancer is described by the TNM system, there will be numbers after each letter that give more details about the cancer—for example, T1N0MX or T3N1M0. The following explains what the letters and numbers mean:
Primary tumor (T)
- TX: Main tumor cannot be measured.
- T0: Main tumor cannot be found.
- T1, T2, T3, T4: Refers to the size and/or extent of the main tumor. The higher the number after the T, the larger the tumor or the more it has grown into nearby tissues. T’s may be further divided to provide more detail, such as T3a and T3b.
Regional lymph nodes (N)
- NX: Cancer in nearby lymph nodes cannot be measured.
- N0: There is no cancer in nearby lymph nodes.
- N1, N2, N3: Refers to the number and location of lymph nodes that contain cancer. The higher the number after the N, the more lymph nodes that contain cancer.
Distant metastasis (M)
- MX: Metastasis cannot be measured.
- M0: Cancer has not spread to other parts of the body.
- M1: Cancer has spread to other parts of the body.
Other Ways to Describe Stage
The TNM system helps describe cancer in great detail. But, for many cancers, the TNM combinations are grouped into five less-detailed stages. When talking about your cancer, your doctor or nurse may describe it as one of these stages:
|Stage||What it means|
|Stage 0||Abnormal cells are present but have not spread to nearby tissue. Also called carcinoma in situ, or CIS. CIS is not cancer, but it may become cancer.|
|Stage I, Stage II, and Stage III||Cancer is present. The higher the number, the larger the cancer tumor and the more it has spread into nearby tissues.|
|Stage IV||The cancer has spread to distant parts of the body.|
Another staging system that is used for all types of cancer groups the cancer into one of five main categories. This staging system is more often used by cancer registries than by doctors. But, you may still hear your doctor or nurse describe your cancer in one of the following ways:
- In situ—Abnormal cells are present but have not spread to nearby tissue.
- Localized—Cancer is limited to the place where it started, with no sign that it has spread.
- Regional—Cancer has spread to nearby lymph nodes, tissues, or organs.
- Distant—Cancer has spread to distant parts of the body.
- Unknown—There is not enough information to figure out the stage.
To learn more about staging for your type of cancer, see the PDQ® cancer treatment summaries for adult and childhood cancers.
• Staging describes the extent or severity of a person’s cancer. Knowing the stage of disease helps the doctor plan treatment and estimate the person’s prognosis.
• Staging systems for cancer have evolved over time and continue to change as scientists learn more about cancer.
• The TNM staging system is based on the size and/or extent (reach) of the primary tumor (T), whether cancer cells have spread to nearby (regional) lymph nodes (N), and whether metastasis (M), or the spread of the cancer to other parts of the body, has occurred.
• Physical exams, imaging procedures, laboratory tests, pathology reports, and surgical reports provide information to determine the stage of a cancer.
What is staging?
Staging describes the severity of a person’s cancer based on the size and/or extent (reach) of the original (primary) tumor and whether or not cancer has spread in the body. Staging is important for several reasons:
- Staging helps the doctor plan the appropriate treatment.
- Cancer stage can be used in estimating a person’s prognosis.
- Knowing the stage of cancer is important in identifying clinical trials that may be a suitable treatment option for a patient.
- Staging helps health care providers and researchers exchange information about patients; it also gives them a common terminology for evaluating the results of clinical trials and comparing the results of different trials.
Staging is based on knowledge of the way cancer progresses. Cancer cells grow and divide without control or order, and they do not die when they should. As a result, they often form a mass of tissue called a tumor. As a tumor grows, it can invade nearby tissues and organs. Cancer cells can also break away from a tumor and enter the bloodstream or the lymphatic system. By moving through the bloodstream or lymphatic system, cancer cells can spread from the primary site to lymph nodes or to other organs, where they may form new tumors. The spread of cancer is called metastasis.
All cancers are staged when they are first diagnosed. This stage classification, which is typically assigned before treatment, is called the clinical stage. A cancer may be further staged after surgery or biopsy, when the extent of the cancer is better known. This stage designation (called the pathologic stage) combines the results of the clinical staging with the surgical results.
A cancer is always referred to by the stage it was given at diagnosis, even if it gets worse or spreads. New information about how a cancer changes over time simply gets added on to the original stage designation. The cancer stage designation doesn’t change (even though the cancer itself might) because survival statistics and information on treatment by stage for specific cancer types are based on the original cancer stage at diagnosis.
What are the common elements of staging systems?
Staging systems for cancer have evolved over time. They continue to change as scientists learn more about cancer. Some staging systems cover many types of cancer; others focus on a particular type. The common elements considered in most staging systems are as follows:
- Site of the primary tumor and the cell type (e.g., adenocarcinoma, squamous cell carcinoma)
- Tumor size and/or extent (reach)
- Regional lymph node involvement (the spread of cancer to nearby lymph nodes)
- Number of tumors (the primary tumor and the presence of metastatic tumors, or metastases)
- Tumor grade (how closely the cancer cells and tissue resemble normal cells and tissue)
Cancer. It’s a small word that can mean a lot of different things. No matter what kind a person has, understanding the stages of cancer and available treatment options is important for optimal treatment.
A stage of a cancer mainly describes the size of the tumor and if it has spread to other areas of the body at the time of diagnosis. It is important for doctors to diagnose the stage of cancer so they can understand how serious the cancer is, as well as develop a prognosis.
Why staging is important
Identifying the stage of cancer acts as a guidepost for the surgical team and helps identify treatment plans or clinical trial options. If a cancer is localized to one area of the body, then surgery or radiotherapy could be enough to remove it completely. If a cancer has spread, chemotherapy, hormone therapy or biological therapies that circulate throughout the bloodstream are required.
How stages are determined
- Lab tests
- CT, MRI, PET or nuclear scans
There are different types of staging systems for different cancers, but the most common is the numbered cancer stage system, which identifies 5 possible stages:
- Stage 0 – Cancer cells that are still in the location where they started and have not spread.
- Stage 1 – Localized cancer that has spread into nearby tissues. It has not yet spread to lymph nodes or other areas.
- Stage 2 – Cancer has spread to a regional area or into nearby tissues or lymph nodes.
- Stage 3 – More advanced regional spread than Stage 2.
- Stage 4 – Cancer has spread to distant parts of the body. This stage is often referred to as metastatic cancer, or a cancer that has spread to other areas of the body.
This system gives doctors a common language to describe the size and spread of cancers. It is also helpful when comparing research studies and determining standardized treatment guidelines for hospitals and clinics.
If you’ve been recently diagnosed with cancer or would like to learn more about treatment options, call the START Center today at (210) 745-6841 or request an appointment.
How does tumor size relate to breast cancer stage?
Tumor size is just one of the factors that doctors consider when determining the stage of a person’s breast cancer. Other factors include:
Lymph node status
When staging a person’s breast cancer, doctors will determine whether it has spread to nearby lymph nodes. They do this by removing one or more of the lymph nodes in the armpit and examining them under a microscope.
Doctors categorize lymph node status using the N value of the TNM system, where:
- NX means that the doctor was unable to assess the lymph node status.
- N0 indicates that the doctor did not detect cancer in the nearby lymph nodes.
- N1, N2, and N3 show that the cancer has spread to nearby lymph nodes. Higher values indicate the involvement of more lymph nodes.
Metastasis is when cancer spreads from its original location in the breast to distant parts of the body, such as the liver, lungs, brain, or bones.
The symptoms of metastatic breast cancer depend on which organs the cancer has spread to, and they can vary greatly. Doctors may use additional scans, tests, and exams to diagnose a person with metastatic breast cancer.
Doctors categorize metastasis using the M value of the TNM system, where:
- MX means that the doctor was unable to assess metastasis.
- MO indicates that the doctor did not detect any metastasis.
- M1 means that the breast cancer has spread to other organs.
Hormone receptor status
When staging breast cancers, doctors test the tumor cells for the presence of hormone receptors. The receptors are proteins that respond to the hormones estrogen and progesterone by telling the cancer cells to grow.
Doctors describe breast cancer that has receptors for estrogen as being estrogen receptor-positive, or ER-positive. They refer to breast cancer that has receptors for progesterone as progesterone receptor-positive, or PR-positive.
Breast cancers that have hormone receptors are far more likely to respond to hormone therapy.
HER2 status refers to whether breast cancer cells are producing too much of a protein called human epidermal growth factor receptor 2 (HER2). Doctors test for HER2 status by taking a sample of the cancer and sending it to a laboratory for analysis.
Doctors describe breast cancer with higher than normal levels of HER2 as being HER2-positive. HER2-positive cancers are typically more aggressive than other types of breast cancer, but they are also more likely to respond to targeted therapies.
Appearance of cancer cells
The appearance, or differentiation, of the cancer cells is another factor in cancer staging. Doctors grade cancer cells according to how similar they appear to noncancerous cells under a microscope.
Doctors classify cancer cells that are close to resembling healthy cells as being low grade or well differentiated. These cancers typically grow more slowly.
High grade, or poorly differentiated, cancer cells appear very different than normal cells and tend to grow faster.