Breast Cancer Staging: What You Need To Know
By Jennifer Welsh
Published on November 02, 2021
Medically reviewed by Doru Paul, MD
When you’ve first been diagnosed with breast cancer, a big question on your mind will likely be: How bad is it? Doctors determine how advanced cancer is through the diagnosis and staging process, labeling your cancer with a stage between 0 and 4.
The higher the stage, the more advanced the cancer is. Treatment options will typically be more aggressive for more advanced cancers, and prognosis, or outlook, is worse.1
Credit: Verywell / Jessica Olah
Breast cancers are uncontrolled growths (tumors) that develop in and around the breast tissue. More advanced cancers have likely also spread to other tissues.
Breast cancer is one of the most common cancers in females. More than 280,000 females are diagnosed with breast cancer each year in the United States. Thankfully, about 90% of females diagnosed with breast cancer are still alive five years later.2
When first diagnosed with cancer, you’ll undergo testing and analysis. Doctors will use those results, along with guidelines set out by the American Joint Committee on Cancer (AJCC), to determine cancer’s stage.3
Purpose of Staging
Staging cancers lets doctors analyze cancer patients as a group, defined by the characteristics of their cancers when first diagnosed. They can then study these groups to determine what the best treatment options are for their cancers and understand the prognosis of these groups.1
This article will explain how breast cancers are staged, what the stages mean, and review the different stages of breast cancer and how they impact treatment options.
Breast Cancer Staging Process
Breast cancer staging is determined by how large tumors are, how far they’ve spread, and other characteristics like the genetics of the tumor. Your cancer stage can be determined before surgery (called the clinical stage) or after surgery (called the pathologic or surgery stage).4
Cancer’s clinical stage is determined through a physical exam, biopsy (removing a small tissue sample for analysis in a lab), and imaging tests. These imaging tests may include X-rays, computed tomography (CT), positron-emission tomography (PET), magnetic resonance imaging (MRI), or ultrasound.5
After surgery, your breast cancer stage will either be confirmed or updated as a pathologic stage, using the features found and any additional information about how far cancer has spread gathered during surgery.
Biopsied Tissue Grading
Biopsied tissue is analyzed by a specialized doctor called a pathologist. These doctors look at the cells under the microscope to determine how wild they look and how many of them are actively dividing. They then give the cells a grade from 1 to 3.
At lower grades, cells look more normal and are slower growing, but in higher grades, the cells are growing faster and look very different from normal cells.6
Hormone Receptor Testing
This biopsied tissue will also be tested to see what receptors the cancer cells are expressing on their surface. This process, called immunohistochemistry, uses special dyes that attach to the receptors and highlight cells with them.7
Cells use receptors like these to take in signals from other parts of the body. Receptors are just special proteins that span the outer layer of the cell, acting both outside and inside the cell.
Knowing what receptors are being expressed in cancer cells helps doctors understand better what treatments may work best against your cancer. The two main hormone receptors that are important for staging breast cancers are:
- Estrogen receptor (ER) binds the hormone estrogen and promotes the growth of the cancer cells.
- Progesterone receptor (PR) binds the hormone progesterone, promoting the growth of the cancer cells.
Breast cancers can be positive or negative for each of these hormone receptors. If they’re negative for both, the cancer is considered hormone receptor negative (HR-). If they’re positive for one or both, the cancer is called hormone receptor positive (HR+).
HER2 Status Testing
Another important characteristic of breast cancer cells is their ability to express the human epidermal growth factor receptor 2 (HER2). HER2 is detected in biopsied samples using special stains.
HER2-positive cancers have higher levels of the HER2 protein, which promotes the growth of cancer. HER2+ cancers tend to grow faster, but this protein is also a target of treatment.8
If a breast cancer is negative for all three receptors (estrogen, progesterone, and HER2), it is considered triple-negative. Triple-negative breast cancers have worse outcomes, as they grow and spread faster than other cancers and have fewer treatment options.7
Doctors will likely also test cells taken during surgery or biopsy to determine what genes your cancer is expressing. Which genes are turned on can help predict how likely the cancer is to come back after treatments.
Three examples of tests you might hear about include the Oncotype Dx, MammaPrint, and Prosigna. These tests are more often used in early-stage cancers.9
For staging, Oncotype DX’s recurrence score may be used on stages 0, 1, 2, or 3A tumors that are HR-positive, HER2-negative, and have spread to fewer than three lymph nodes. The higher the score (out of 100), the more likely the cancer is to recur and the more benefit the patient would see from chemotherapy.
Cancer staging typically follows the TNM system. This system defines three features of cancer in a way that can be widely applied to other solid cancers.
Each of the three letters gets a number assigned, so any given cancer can be described by these three factors, where the numbers associated with these three letters indicate how advanced a particular characteristic is. An "X" means the characteristic can’t be measured.1
"T" for Tumor
The "T" in TNM stands for the primary tumor—the first and original cancer that developed. Doctors will measure the size of the main tumor and determine how far within an organ’s layers it has spread.
A T measurement of 0 to 4 describes the size and extent of the main tumor’s growth. A 0 would indicate that the main tumor can’t be found or described.4
"N" for Nodes
"N" stands for the lymph nodes—the small balls of tissue that filter the immune system’s fluids and act as a home for immune cells. Lymph nodes are one of the major ways that cancers can spread throughout the body, so they’re often the first place cancer shows up when it starts to spread beyond its origin.10
An N number is given between 1 and 3, defining how many lymph nodes cancer has spread to. An N0 means the cancer was found in no lymph nodes. To be counted as cancerous, the lymph node has to have a growth of more than 200 cancer cells—a size of about 0.2 millimeters.
Cancer cell masses under this number aren’t counted toward the N staging but are noted with an N0(i+) or N0(mol+). N0(i+) is used when these cells are detected using microscope techniques. N0 (mol+) is used when the presence of cancer is detected using a molecular technique called RT-PCR.4
"M" for Metastases
When cancer has metastasized it has spread from its origin to other organs. "M" in the TNM staging standards stands for metastasis. Metastasis makes cancers harder to cure.
M1 means cancer has spread to other major organs. Common organs that breast cancer spreads to include the lungs, liver, and bones. A 0 indicates there’s no evidence that cancer has spread.4
Stage Does Not Change
Cancer’s stage never changes from when it was first diagnosed. Cancers are always referred to by the stage given at first diagnosis, even if the tumor grows, spreads, or goes away and comes back. Additional details may be added to cancer’s stage, including its recurrence.1
Stages of Breast Cancer
Your cancer's TNM numbers are used to determine your cancer's stage. These stages are grouped from 0 to 4 and can have many substages.
Generally, stage 0 cancer is defined as abnormal cells that have not started to spread. Stages 1, 2, and 3 tumors are cancerous, have started to spread and grow larger. Stage 4 cancers, generally, are the most advanced and have spread to distant parts of the body.
The AJCC released the eighth edition of cancer staging guidelines in 2018. The latest edition incorporates specific markers found in the blood that can help indicate breast cancer’s prognosis. It also includes cancer’s HER2, ER, and PR status.11
These new guidelines include cancer’s Oncotype DX score, for cancers that are ER-positive, HER2 negative, and that haven’t spread to the lymph nodes.3
The latest guidelines also incorporate cancer’s grade—the score given to cancer cells after they’re examined under the microscope by a pathologist.12
Because it takes all these different factors into consideration, breast cancer staging is complex. There are multiple ways a patient could end up with a given stage. But these factors are what doctors must take into account when they’re treating breast cancer patients.
Any given stage of breast cancer is made up of combinations of lymph node numbers, biomarker status, cancer’s receptor characteristics and genetics, and the size and spread of the original tumor.
Below are some general guidelines for the stages of breast cancer, though a cancer's actual stage can be impacted by the tumor’s hormone receptor and HER2 status and Oncotype DX recurrence scores.
If you’re wondering why your particular cancer has been staged the way it has, ask your doctor for further explanations of what factors were at play when giving you that particular staging.
- Stage 0 breast cancer is also called ductal carcinoma in situ (DCIS) or Paget's disease of the breast. It is a precancerous stage, or non-invasive.4 These cells may look abnormal, but they aren’t cancerous (yet) and haven’t invaded any other parts of the breast or surrounding tissues or organs.12
- Stage 1 breast cancer typically has started to grow into surrounding breast tissues, either did not spread into the lymph nodes (stage 1A), or only spread minimally into the lymph nodes (stage 1B).12
- Stage 2 breast cancer typically indicates a larger primary tumor or that cancer has spread to more lymph nodes.12
- Stage 3 breast cancer is often called invasive breast cancer. It has spread further than stage 2 but has not metastasized beyond the local tissues and organs near the breast. It also includes most inflammatory breast cancers, which often lead to breast skin being red, warm to the touch, or swollen, and may have spread to lymph nodes in the skin.
- Stage 4 breast cancer, also called metastatic breast cancer, has by definition spread to organs in other parts of the body. These organs may include the lungs, skin, bones, liver, or brain.
Your healthcare team will recommend treatment based on breast cancer staging. The specific treatments also depend on many individual factors, so always discuss your options with your healthcare professional.
Stage 0 Breast Cancer Treatment Options
Stage 0 cancers can be treated with surgery to remove the mass and hormone therapy to ensure cancer doesn’t develop.13
Stage 1 Breast Cancer Treatment Options
Stage 1 breast cancers are usually treated with surgery to remove the mass, potentially with radiation therapy to treat the area.
Hormone therapies and chemotherapy can help reduce the risk that cancer will come back. Lymph nodes will also be biopsied or dissected to detect cancer.
Targeted therapies may also be used for HER2-positive stage 1 cancers.14
Stage 2 Breast Cancer Treatment Options
Treatment options for stage 2 breast cancers include surgery to remove the tumor (a lumpectomy and radiation to the breast or the chest wall), or breast removal (mastectomy), which may or may not require radiation treatments.15
Chemotherapy may be used to shrink the tumor before surgery and is commonly recommended to reduce the risk of recurrence.
Lymph nodes will be removed and biopsied, and others may need to be treated with radiation.
You may also get hormone therapy, targeted therapy, or immunotherapy depending on the characteristics of your cancer.
Stage 3 Breast Cancer Treatment Options
Treatment for stage 3 breast cancers typically involves a combination of surgery (lumpectomy or mastectomy) along with chemotherapy to shrink the tumor before surgery and radiation after surgery to treat the chest wall and/or lymph nodes. Lymph nodes will also likely be removed during surgery.
Stage 4 Breast Cancer Treatment Options
Treatment options for stage 4 breast cancer aim to ease any symptoms, improve quality of life, and extend life span. This may include hormone therapy, targeted therapy, chemotherapy, immunotherapy, radiation, or surgery.17
Immunotherapies may be an option for high-risk (stage 2 and 3) triple-negative cancers.
Breast cancer staging helps guide treatment options. It requires a physical examination, biopsy, imaging, hormone receptor testing, and genetic testing. The stage is determined by criteria in the AJCC staging system, from stage 0 to stage 4. The stage of the cancer does not change once it is determined.
A Word From Verywell
Being diagnosed with breast cancer, especially if it’s advanced, will turn your life upside down. Trying to figure out why you’re diagnosed with a certain stage of cancer can make your brain feel like a scrambled egg.
Breast cancer staging is an ever-more complex procedure, but it gives doctors a better idea of how best to treat your specific cancer and a better handle on what your prognosis may be.
Thankfully, breast cancer, even in relatively advanced stages, has a pretty good prognosis and many effective treatment options. With more than a quarter of a million Americans diagnosed with breast cancer every year, you’re definitely not alone.
FREQUENTLY ASKED QUESTIONS
- What is the staging process for breast cancer?
To determine the stage of breast cancer, doctors will perform a physical exam, take a detailed personal and family history. They’ll also order imaging tests and blood tests. They’ll either take a tissue sample of the mass or decide to remove the mass to test it and nearby lymph nodes.
This tissue sample will be analyzed to determine how wild the cancer cells look. The cancer sample will also be tested for receptors that give the cancer various characteristics.
A test called the Oncotype DX will be done on samples from cancerous tissue, which gives a recurrence score based on its genetic makeup.
Learn More: Breast Tumor Size and Staging
- Who created the breast cancer staging system?
Cancer staging systems used for most solid cancers are designed by the American Joint Committee on Cancer and International Union Against Cancer. They were most recently updated in 2018. They’re often called the TNM staging system or the AJCC staging system.18
Posted in: Medical/Science, Staging