Breast Cancer Stages

After a breast cancer diagnosis, one of the next steps is gathering more information about the cancer. This process is called staging. Staging helps determine how early or advanced the cancer is.

Staging is based on information from:

• Radiology imaging
• Pathology (from biopsy or surgery) 
• Clinical exam

This section provides an overview of how breast cancer is staged. More detailed information about each stage, including treatment options and survival rates, can be found here:

• Stage 0 breast cancer overview
• Stage 1 breast cancer overview
• Stage 2 breast cancer overview
• Stage 3 breast cancer overview
• Stage 4 breast cancer overview

On January 1, 2018, the American Joint Committee on Cancer (AJCC) launched new staging guidelines for breast cancer.

---

Jump to:

Determining breast cancer stage
Breast cancer tests
Breast cancer stage groups
TNM system
Grading system
Biomarker testing
Clinical versus pathology staging
Questions to ask your oncologist

---

Determining breast cancer stage

In breast cancer, staging looks at several important factors, including the size and location of the tumor, whether the cancer has spread, how the cells look under a microscope (called the grade), and whether certain markers are present on the cancer cells. 

The TNM system, tumor grade, and biomarker results are used together to determine the stage of breast cancer. Staging helps guide treatment decisions, but it does not predict your future. Information on breast cancer staging can be found in your pathology report from a biopsy or after surgery. 

---

Breast cancer tests

The following procedures and tests may also be used in the staging process:

• Breast biopsy: A breast biopsy is a procedure used to remove a small sample of breast tissue so it can be tested for cancer. Most biopsies are done using a needle and are guided by imaging, such as ultrasound, mammogram, or MRI. The sample is examined under a microscope to determine if cancer is present and to learn more about the type of breast cancer.
• Axillary lymph node biopsy: If a lymph node in the underarm (axilla) looks abnormal on imaging or exam, a needle biopsy may be done to check for cancer. This is often guided by ultrasound. The sample is examined to see if cancer has spread to the lymph nodes, which can help guide staging and treatment decisions.
• Breast surgery: Surgery is used to remove breast cancer and may include a lumpectomy (removal of the tumor) or a mastectomy (removal of the breast). The tissue that is removed is examined under a microscope to determine the size of the cancer, which helps confirm the stage and guide treatment decisions.
• Sentinel lymph node biopsy: At the time of surgery, a sentinel lymph node biopsy is often performed to check if cancer has spread. The sentinel lymph node is the first lymph node that drains fluid from the breast, so it’s the most likely place cancer would spread first. To find it, a small amount of dye and/or a radioactive tracer is injected near the tumor. This travels to the sentinel lymph node, which is then removed and checked for cancer. If no cancer is found, more lymph nodes usually do not need to be removed. In some cases, more than one sentinel lymph node may be identified and tested. 
• CT scan (computed tomography): This is a type of imaging test that uses X-rays to take detailed images of bones, organs, and tissues. It shows images from different angles to give a clearer view than a standard x-ray. A contrast dye is given through a vein or by mouth. For breast cancer staging, CT scans are often done of the chest, abdomen, and pelvis to check if the cancer has spread.
• MRI (magnetic resonance imaging): During a breast MRI, a magnet and radio waves (no radiation) are used to take detailed pictures of the breast. It can help show areas that look different from normal tissue, assess the size of the cancer, and identify other potential areas of concern.
• Bone scan: A small amount of a safe radioactive tracer is injected into a vein. It travels through the body and collects in areas of the bone that are more active, such as areas of damage or repair. These areas may be checked more closely to see if cancer has spread to the bone.
• PET scan (positron emission tomography scan): A small amount of a radioactive tracer is injected into a vein. This tracer acts like sugar (glucose) and travels through the body. Cells that use more energy, such as cancer cells, absorb more of it. The PET scanner then takes images of the body and highlights areas where the tracer has collected. These areas may indicate where cancer has spread.
• Blood tests: Blood tests alone cannot determine if cancer has spread (metastasized), but they may help guide the need for additional imaging or testing.
  • Liver function tests (LFTs): These include AST, ALT, ALP, and bilirubin. Abnormal results may lead to further testing to evaluate the liver.
  • Alkaline phosphatase (ALP): Higher levels may lead to additional evaluation of the bones or liver.
  • Calcium: Higher levels may lead to further evaluation of the bones.

---

Breast cancer stage groups

There are 3 types of breast cancer stage groups:

• Clinical prognostic stage: Clinical staging is the first step in determining the stage of breast cancer. It is based on information from the physical exam, imaging tests, and biopsy results. Clinical staging is determined using the TNM system, tumor grade, and biomarker results (ER, PR, and HER2). Lymph nodes are evaluated using imaging and, in some cases, a biopsy of the underarm (axillary) lymph nodes.
• Pathological prognostic stage is determined after surgery and is based on what is found in the breast tissue and axillary lymph nodes that are removed and examined. It uses the TNM system, tumor grade, and biomarker results (ER, PR, and HER2).
• Anatomic stage is based on the size of the tumor and whether the cancer has spread, as described by the TNM system. This type of staging does not include tumor grade or biomarker results (ER, PR, and HER2) and may be used in parts of the world where biomarker testing is not available. In the United States, it is less commonly used.

---

TNM system

The TNM system is the foundation of how breast cancer is staged. It describes the size of the tumor and whether the cancer has spread to nearby lymph nodes or other parts of the body.

TNM stands for:

• T = Tumor: the size and location of the tumor
• N = Lymph node: the size and location of lymph nodes where cancer has spread
• M = Metastasis: the spread of cancer to other parts of the body

For breast cancer, the TNM system describes the tumor as follows:

Tumor (T)

Describes the size and location of the tumor.

• TX: Primary tumor cannot be assessed.
• T0: No evidence of a primary tumor in the breast.
• Tis: Carcinoma in situ. There are 2 main types:
  • Tis (DCIS): Ductal carcinoma in situ (DCIS), or Stage 0 breast cancer, is when abnormal cells are found inside the lining of a breast duct. The abnormal cells have not spread outside the duct to other tissues in the breast (considered invasive breast cancer). While DCIS is not invasive, some cases may develop into invasive breast cancer over time.
  • Tis (Paget’s disease): Paget’s disease of the nipple is a rare type of breast cancer that starts in the skin of the nipple and can spread to the darker skin around it (the areola). Paget’s disease itself is not staged using the TNM system. However, if it occurs along with an invasive breast cancer deeper in the breast, the TNM system is used to stage the invasive cancer.
• T1: The tumor is 20 mm (2cm) or less. There are smaller subtypes within T1:
  • T1mi: ≤ 1 mm (up to about the size of grain of sand)
  • T1a: > 1 mm and ≤ 5 mm (up to about the size of a sesame seed)
  • T1b: > 5 mm and ≤ 10 mm (up to about the size of a pea)
  • T1c: > 10 mm and ≤ 20 mm (up to about the size of a grape)
• T2: The tumor is > 20 mm and ≤ 50 mm (about the size of a walnut or small lime)
• T3: The tumor is > 50 mm. (about the size of a golf ball or larger)
• T4: The tumor has grown beyond the breast tissue into nearby areas:
  • T4a: Grown into the chest wall
  • T4b: Grown into the skin, an ulcer has formed on the surface of the skin on the breast, small tumor nodules have formed in the same breast as the primary tumor, and/or there is swelling of the skin on the breast
  • T4c: Grown into the chest wall and the skin
  • T4d: Inflammatory breast cancer, which typically causes redness and swelling of the breast skin, sometimes covering a large portion of the breast. The skin may look pitted or thickened, like the peel of an orange (called peau d’orange).

Lymph node (N)

Describes whether cancer has spread to nearby lymph nodes, and where those lymph nodes are located.

When lymph nodes are removed during surgery and examined under a microscope, this is called pathologic staging (pN).

• NX: Lymph nodes cannot be assessed
• N0: No cancer is found in the lymph nodes, or only very tiny amounts (≤ 0.2 mm)
• N1: Cancer has spread to a small number of nearby lymph nodes
  • pN1mi: Very small spread to axillary (underarm) lymph nodes (> 0.2 mm but ≤ 2 mm)
  • pN1a: Cancer in 1–3 axillary lymph nodes, with at least one area > 2 mm
  • pN1b: Cancer found in lymph nodes near the breastbone (internal mammary nodes) on the same side, seen on sentinel lymph node biopsy, not in the axillary lymph nodes
  • pN1c: Combination of pN1a and pN1b
• N2: Cancer has spread to more lymph nodes, or to a different group of nodes
  • pN2a: Cancer in 4-9 axillary lymph nodes, with at least one area > 2 mm
  • pN2b: Cancer found in lymph nodes near the breastbone (internal mammary nodes) on the same side of the body, found by sentinel lymph node biopsy. Cancer is not found in the axillary lymph nodes after surgery.
• N3: Cancer has spread more extensively to lymph nodes
  • pN3a: Cancer in 10 or more axillary lymph nodes, and at least one of the lymph nodes is larger than 2 mm, or cancer has spread to lymph nodes below the collarbone
  • pN3b: Cancer in axillary lymph nodes (pN1a or pN2a), with at least one lymph node larger than 2 mm, and cancer in lymph nodes near the breastbone (internal mammary nodes). This may be seen on imaging (cN2b) or found on biopsy (pN1b)
  • pN3c: Cancer in lymph nodes above the collarbone on the same side

When lymph nodes are evaluated using imaging tests like a mammogram, ultrasound, or MRI, this is called clinical staging (cN). Clinical staging of lymph nodes is not described here.

Metastasis (M)

Cancer can spread from where it started to other parts of the body (metastasis) in a few ways:

• Through the lymph system: Cancer may travel through lymph vessels to nearby lymph nodes or other parts of the body. Your report may mention positive lymph nodes or lymphatic (lymphovascular) invasion. 
• Through the bloodstream. The cancer spreads from where it originated and has entered the blood to travel to other parts of the body such as bone, liver, lungs, or brain. The report may mention vascular invasion.

The metastatic tumor is the same type of cancer as the primary (breast)  tumor. For example, if breast cancer spreads to the bone, the cancer cells in the bone are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer. 

Describes whether cancer has spread to other parts of the body beyond the breast and nearby lymph nodes.

• M0: There is no sign that cancer has spread to other parts of the body.
• M1: Cancer has spread to other parts of the body, most often the bones, lungs, liver, or brain. It may also be found in distant lymph nodes. This is considered metastatic breast cancer.

---

Grading system

The grading system is used to describe how quickly a breast tumor is likely to grow and spread. 

It looks at how different cancer cells appear compared to normal cells under a microscope. Low-grade cancer cells look more like normal cells and tend to grow and spread slowly. High-grade cancer cells look more abnormal and tend to grow and spread more quickly.

To describe how abnormal the cancer cells and tissue are, the pathologist will assess the following three features:

• How much of the tumor tissue still looks like normal breast tissue
• The size and shape of the cell nuclei
• How many dividing (growing) cells are present

Each feature is given a score from 1 to 3. A score of 1 means the cells look more like normal cells, while a score of 3 means they look more abnormal. The scores are added together for a total between 3 and 9.

There are three possible grades:

• Score 3-5: Grade 1 (low grade, or well differentiated)
• Score 6-7: Grade 2 (intermediate grade, or moderately differentiated)
• Score 8-9: Grade 3 (high grade, or poorly differentiated)

---

Biomarker testing

Biomarker testing shows whether breast cancer cells have certain receptors (proteins). These results help guide treatment planning.

Estrogen and progesterone are natural hormones in the body, and many healthy breast cells have receptors for them. In some breast cancers, these receptors can help cancer cells grow.

Estrogen = a hormone; think of it like a key.

Estrogen receptor (ER) = a protein inside cells that estrogen (the hormone) binds to; think of it like a lock.

When estrogen attaches to an estrogen receptor, it can send signals telling the cell to grow and divide.

HER2 is another important protein found on breast cells. In some breast cancers, there are higher than normal levels of HER2, which can cause cancer cells to grow more quickly.

To check for these receptors, a sample of the tumor is taken during a biopsy or surgery.

• Estrogen receptor (ER): If breast cancer cells have estrogen receptors, the cancer is called ER positive (ER+). If not, it is ER negative (ER-).
• Progesterone receptor (PR): If breast cancer cells have progesterone receptors, the cancer is called PR positive (PR+). If not, it is PR negative (PR-).
• HER2 (human epidermal growth factor receptor 2): If breast cancer cells have higher-than-normal levels of HER2, the cancer is HER2+ (positive) . If levels are normal, it is HER2- (negative). HER2+ cancers tend to grow and spread more quickly than HER2- cancers.
  • Sometimes, a HER2 test result is equivocal (unclear or “in between”). When this happens, an additional test, called a FISH test (fluorescence in situ hybridization), is done to determine whether the cancer is HER2-positive or HER2-negative.

Sometimes the breast cancer cells will be described as “triple negative” or “triple positive”.

• Triple negative: Breast cancer cells do not have ER or PR receptors and do not have higher-than-normal HER2 levels (ER-, PR-, HER2-).
• Triple positive: Breast cancer cells have ER and PR receptors and have higher-than-normal HER2 levels (ER+, PR+, HER2+).

Some treatments, called hormone therapy, block estrogen and progesterone from attaching to their receptors, which can help slow or stop cancer growth.

Other treatments, known as targeted therapy, focus on HER2 on the surface of cancer cells, helping to block signals that tell the cancer to grow.

---

Clinical versus pathology staging

Staging happens in two phases: Before surgery (clinical stage) and after surgery (pathological stage).

The TNM system, tumor grading, and biomarker status are reported using two types of staging: clinical and pathological. Clinical staging is based on information gathered before treatment, such as physical exams, imaging, and biopsy results. 

For example, when a provider enters details from your breast biopsy pathology report (results) they are using the clinical stage within the TNM system.

Pathological staging, on the other hand, is based on findings after surgery, when the tumor and surrounding tissue can be examined more thoroughly. When providers enter information from a surgical pathology report, they are selecting the pathological stage within the TNM system.

Because these stages are based on different types of information, it’s common for them to be different. The clinical stage is an informed estimate of the cancer before treatment, based on exams and imaging. The pathological stage is determined after surgery, when the tissue can be examined more closely, and provides a more complete and accurate picture. 

If treatment such as chemotherapy is given before surgery (called neoadjuvant therapy), the pathological stage may be labeled with a “y” (for example, ypT or ypN). This shows that the staging reflects how the cancer responded to treatment before surgery. 

Here are three examples that show how the TNM system, tumor grade, and biomarker status are used together to determine the pathological prognostic stage for someone whose first treatment is surgery:

Example 1: If the tumor size is 30 millimeters (T2), has not spread to nearby lymph nodes (N0), has not spread to distant parts of the body (M0), and is:

• Grade 1
• ER-
• PR-
• HER2+

The pathological stage is 2A pT2 pN0 M0 G1 ER- PR- HER2+.

Example 2: If the tumor size is 53 millimeters (T3), has spread to 4 to 9 axillary lymph nodes (N2), has not spread to other parts of the body (M0), and is:

• Grade 2
• ER+
• PR-
• HER2+

The pathological stage is 3A pT3 pN2 M0 G2 ER+ PR- HER2+.

Example 3: If the tumor size is 65 millimeters (T3), has spread to 3 axillary lymph nodes (N1a), has spread to the lungs (M1), and is:

• Grade 1
• ER-
• PR-
• HER2+

The pathological stage is 4 (metastatic breast cancer).

Talk with your doctor about your breast cancer stage and what it means for your care. Your stage helps guide your treatment plan so you can get the approach that’s best for you. 

---

Questions to ask your oncologist

Your doctor will share a lot of information, which can feel overwhelming. Consider bringing someone with you to take notes and offer support.

About your diagnosis:

• What stage is my breast cancer, and what does it mean?
• Is my cancer hormone receptor-positive or negative? What is my HER2 status?

About your treatment plan:

• How does my stage affect my treatment options?
• What treatments do you recommend, and why?
• Will I need chemotherapy, now or later?
• What is the goal of my treatment?

Next steps and support:

• Will I need additional tests or to see other specialists?
• Should I consider genetic testing?
• Should I consider getting a second opinion?
• Are there clinical trials that may be right for me?
• What does “remission” mean in my situation?

---

---