Breast cancer stages aim to describe how far cancer has progressed. The stage will affect the different symptoms and treatment options.

Doctors use various ways to stage breast cancer. Four broad stages define where the cancer is, whether it is still in its original location or if it has spread to other parts of the body.

However, a doctor will also use other systems and information to identify the stage and decide which treatment is most suitable and what the outlook is likely to be.

It is worth noting that the stage is not the only factor that affects treatment and other decisions. Other considerations include markers such as hormone receptivity, the cancer grade, the type, the person’s overall health, and so on.

Each case will be different. However, a doctor can help the individual understand how cancer will affect them and what to expect.

The American Joint Committee on Cancer (AJCC) oversees the staging of breast cancer. As a result, all cancer doctors describe and classify the stages of cancer in the same way.

AJCC’s staging is the most commonly used method for breast cancer and allows all doctors to describe, classify, and stage cancer in the same way. It involves two systems: pathological staging and clinical staging.

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One way to identify the stage is to look at body tissue and see how far cancer cells have spread. This gives the following broad stages:

  • In situ: There is a change in cells that could become cancerous and invade other tissue over time.
  • Localized: A tumor is present but has not spread.
  • Regional: Cancer has spread beyond the original location to nearby lymph nodes.
  • Distant or metastatic: Cancer has spread to other parts of the body and other organs beyond the original location.

However, this description alone does not reflect the complexities of breast cancer. For this reason, doctors also use other methods and other information.

TNM staging

Crucial to breast cancer staging is the TNM system.

The letters TNM mean the following:

  • T = tumor: This indicates the extent or size of the tumor and how much breast tissue it involves.
  • N = nodes: This shows whether cancer has spread to the lymph nodes and how many it has affected.
  • M = metastasis: This is when cancer has spread to other parts of the body, such as distant organs, tissues, and the bones.

The TNM staging system also uses numbers. The numbers, from 0 to 4, describe the stage, and information from the TNM staging helps determine the number.

Other factors affecting treatment options and outlook are the status and grade.

Tumor status

A doctor will use test results showing the presence and absence of specific biomarkers to assess the tumor status. They will ask one or more of the following questions while reviewing the results:

  • Are there estrogen-receptor proteins (Is is ER+ or ER-)?
  • Are there progesterone receptor proteins (Is it PR+ or PR-)?
  • Does it produce high levels of a protein HER2 (Is it HER2+ or HER2-)?
  • Is it triple negative, in other words, EE-, PR- and HER2-?
  • What genetic patterns show up if genetic testing is done?

Cancer grading

The grade indicates how fast cancer is likely to grow and to what extent they look like normal cells.

It can be:

  • Grade 1 or low grade: The cells look similar to healthy tissue and will likely grow slowly.
  • Grade 2 or intermediate grade: The cells looks somewhat different and will likely grow at a moderate rate.
  • Grade 3 or high grade: The cells look very different and may be fast growing.

Diagnostic tests

To determine the stage, a doctor may perform tests, including:

It is also worth noting that, while initial tests can help stage and grade cancer, the doctor may need to revise their decision as more information becomes available.

Lab tests on a tumor after surgery, for example, may provide information that is different from the results of a biopsy because there is more tissue to analyze.

A person with stage 0 breast cancer has a noninvasive cancer type.

This means that cancer cells are present but they have not spread anywhere else in the body. With some types, however, there may be a risk of breast cancer developing later.

Examples of noninvasive breast cancer are ductal carcinoma in situ (DCIS) and lobular carcinoma in situ (LCIS).

In DCIS, the cells that line the milk ducts of the breast have become cancer, but they have not spread into surrounding breast tissue.

In LCIS, they are present in the lining of milk-producing glands in the breast but have not spread beyond these lobules.

A mammogram may detect DCIS. However, it does not usually detect LCIS. A person may receive a diagnosis of LCIS during a biopsy for another breast problem.

Early diagnosis of stage 0 breast cancer means that a person can receive prompt treatment. This might prevent cancer from turning into an invasive breast cancer type.

Treatment for stage 0 breast cancer

Not everyone with stage 0 breast cancer needs treatment. If tests suggest that treatment is a good idea, options include:

Surgery

A lumpectomy involves removing cancerous cells from the breast. It is an option when the cells remain in one area. This is a relatively short and simple procedure, and a person should be able to go home after the surgery on the same day.

If cancerous cells appear throughout the breast, the doctor may recommend a mastectomy, which involves removing the entire breast. Plastic surgeons can rebuild the breast at the same time or a later date.

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Hormone therapy

The hormone estrogen, found naturally in the body, can impact some types of breast cancer. If a person has estrogen receptor-positive (ER+) or progesterone receptor-positive (PR+) breast cancer, a doctor may suggest hormone treatment in addition to surgery.

In stage 1 breast cancer, the cancerous cells have invaded the surrounding breast tissue. Stage 1 breast cancer has two subcategories — 1A and 1B.

Stage 1A

People with stage 1A breast cancer have a tumor measuring no more than 2 centimeters (cm) in diameter that has not spread outside the breast.

Stage 1B

This is invasive breast cancer. A person may have no tumor in the breast, but cancer cells have formed into clusters 0.2–2 (millimeters) mm in diameter. They may also be in the lymph nodes.

Alternatively, there may be a tumor up to 2 cm in the breast and small groups of cancer cells measuring 0.2–2 mm developing in the lymph nodes.

If this is the case and the cancer is ER+ or PR+, a doctor is still likely to classify it as stage 1A cancer.

Microscopic invasion is where cancer cells have begun to spread outside the milk duct lining or lobule. If this happens, doctors may still classify cancer as stage 1 breast cancer, providing these cells do not measure more than 1 mm.

Learn more about locally advanced breast cancer, when a tumor is large but has not spread to other areas.

Treatment for stage 1 breast cancer

Doctors can offer a variety of treatment options for stage 1 breast cancer, although surgery is the primary treatment.

Surgery

A lumpectomy or mastectomy are both viable surgical options for people with stage 1 breast cancer. A doctor will decide what surgery is most appropriate depending on the location of the primary tumor, how large it is, the size of the breast, family history, genetics, and the person’s preference.

The doctor may also carry out a biopsy on one or more lymph nodes.

After removing the tissue, they will send it to a laboratory for further tests. The results will help inform decisions on the next stage of treatment.

Radiation therapy

Radiation therapy is a standard treatment for stage 1 breast cancer. However, the decision will depend on factors such the age of the person, the type of cancer, the size of the tumor, and whether there are cancer cells in the lymph nodes.

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Hormone therapy

If the breast cancer is ER+ or PR+, hormone therapy may be effective. Hormone therapy works by preventing the growth of estrogen, which helps cancer grow, by blocking estrogen from attaching to tissue and fuelling cancer growth, or both.

Hormone therapy can reach cancer cells in the breast, as well as other areas of the body, and it can reduce the risk of cancer returning.

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Chemotherapy

In some cases, a doctor may recommend chemotherapy. This will depend on the size of the tumor, how likely cancer is to spread, and the hormone receptor status of the tumor. Not all types respond to this treatment.

The doctor may suggest having a test known as Oncotype DX, which can help show if the benefits of chemotherapy are likely to outweigh the disadvantages for specific individuals. They will base this suggestion on factors such as the hormone receptor status of the tumor and how far it has spread.

However, the National Cancer Institute has noted that the test may be less accurate for Black American women than for non-Hispanic white women, based on a study published in 2021.

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Targeted therapy

If a person’s breast cancer is HER2 positive, a doctor may recommend using targeted therapy, such as trastuzumab (Herceptin), either alone or alongside chemotherapy.

As the name implies, targeted therapies have a specific target. Chemotherapy, on the other hand, affects the whole body. Targeted therapies can have adverse effects. However, these are usually less severe than the side effects of chemotherapy.

Is chemotherapy the only option? Here, find out about some possible alternatives to discuss with a doctor.

Stage 2 breast cancer also has subcategories known as 2A and 2B.

Stage 2A breast cancer is invasive cancer:

  • There is no tumor growth in the breast itself, but cancerous masses over 2 mm in diameter are growing in up to three axillary lymph nodes (in and around the armpit) or lymph nodes near the breastbone.
  • A tumor in the breast is under 2 cm in diameter but has spread to the axillary lymph nodes.
  • The tumor is 2–5 cm in diameter but has not spread to the axillary lymph nodes.

Stage 2B breast cancer is an invasive breast cancer where:

  • A tumor 2–5 cm in diameter is growing in the lymph nodes alongside clusters of cancerous cells. These cancerous cells form groups 0.2 mm–2 mm in size.
  • There is a tumor 2–5 cm in diameter, and cancerous cells have spread to one to three axillary lymph nodes or lymph nodes by the breastbone.
  • The tumor is larger than 5 cm, but cancerous cells have not spread to the axillary lymph nodes.

Learn more here about stage 2 breast cancer.

Treatment for stage 2 breast cancer

The most common type of treatment for stage 2 breast cancer is surgery.

Surgery

In most cases, treatment involves removing the cancer. The person may undergo a lumpectomy or mastectomy. The doctors and the individual can decide based on the size and location of the tumor. The surgeon may also remove one or more lymph nodes.

Combination therapy

A doctor may recommend a combination of radiation therapy, chemotherapy, and hormone therapy (if the cancer is hormone receptive) to people with stage 2A or 2B breast cancer.

Neoadjuvant therapy

In some cases, a doctor may recommend neoadjuvant therapy, which is chemotherapy before surgery to reduce the size of a tumor.

The subcategories for stage 3 breast cancer are 3A, 3B, and 3C.

3A breast cancer is an invasive breast cancer where:

  • There is no tumor in the breast, or a tumor of any size is growing alongside cancer found in four to nine axillary lymph nodes or the lymph nodes by the breastbone.
  • A person has a tumor greater than 5 cm. They also have clusters of breast cancer cells in the lymph nodes that are between 0.2–2 mm in diameter.
  • The tumor is larger than 5 cm. The cancer has also spread to one to three axillary lymph nodes or the lymph nodes near the breastbone.

Stage 3B breast cancer is invasive breast cancer where:

  • A tumor of any size has spread into the chest wall or skin of the breast, causing swelling or an ulcer to develop.
  • Cancer cells may also be present in to up to nine axillary lymph nodes.
  • They may be present in lymph nodes by the breastbone.

Find out more about stage 3 breast cancer here.

Inflammatory breast cancer

If cancer spreads to the skin of the breast, a person may have inflammatory cancer. Doctors consider this at least stage 3b.

Symptoms include:

  • reddening of the skin
  • breast swelling
  • warmth in the breast

Cancer cells are present in the lymph nodes and possibly the skin.

Stage 3C breast cancer is an invasive breast cancer where:

  • There is no tumor in the breast or the tumor may be any size and has spread into the wall of the chest or the skin of the breast.
  • Cancer may also be present in 10 or more axillary lymph nodes.
  • Cancer has spread to a person’s lymph nodes above or below the collarbone or axillary lymph nodes or lymph nodes located close the breastbone.

Treatment for stage 3 breast cancer

Treatment for stage 3 breast cancer may include the following, depending on the type of cancer and other factors:

  • chemotherapy
  • surgery
  • radiation (in some cases)
  • targeted therapy
  • hormone therapy
  • neoadjuvant chemotherapy before surgery to shrink a tumor

People with stage 3 breast cancer will probably need radiation therapy to kill off any remaining cancer cells. Doctors may also recommend hormone therapy, as well as additional targeted therapies, if necessary.

A person with stage 4 breast cancer, also called metastatic breast cancer, has cancer that has spread to nearby lymph nodes and also more distant lymph nodes and other organs in the body.

Stage 4 breast cancer is the most advanced stage. Stage 4 breast cancer also may be breast cancer that returned to affect other parts of the body. Cancer that has returned in other parts of the body is called recurrent metastatic breast cancer

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Treatment for stage 4 breast cancer

Treatment for stage 4 breast cancer may include the following, either alone or in combination:

  • chemotherapy
  • hormone therapy
  • targeted therapy, which targets the protein that allows cancer cells to grow
  • immunotherapy, which boosts the body’s ability to fight cancer

In rare cases, a surgeon will operate to try and remove tumors. This is not usually the first option.

However, a doctor may recommend surgery to help relieve pain or other issues that may develop as a result of stage 4 breast cancer. These include spinal cord compression, removing single masses caused by metastasis, and fixing any broken bones.

A doctor may also prescribe medication to treat related symptoms, such as pain.

New treatments and therapies are emerging all the time, and anyone who has breast cancer at any stage can volunteer to try out these new treatments. People considering this should talk with their doctor to see whether any trials are available in their area.

As well as numbers, a zero or an ‘X’ often follow the letters T, N, and M. According to the AJCC, the meanings are as follows:

  • TX: There is not enough information about the presence or size of the tumor to define it.
  • T0: No evidence of an invasive primary tumor is present. Cancer cells have not yet grown into healthy tissue.
  • T1–T3: This describes the size or extent of the tumor.
  • NX: There is no information about the lymph nodes.
  • N0: There is no evidence of cancer in the nearby lymph nodes.
  • N1–N3: This describes the size or extent of lymph node involvement.
  • MX: There is no information about distant metastasis.
  • M0: No evidence of distant metastasis is present.

The stages of breast cancer help doctors and individuals understand how far cancer affects the body and which treatment options may be effective. However, other factors can also play a role in making treatment decisions.

They include:

  • age
  • pregnancy status
  • family history
  • if testing shows changes in specific genes, such as BRCA1, BRCA2, and PALB2
  • overall health
  • individual choice

Learn more here about how age and other factors affect the risk of breast cancer.

The outlook for breast cancer will depend on the stage at diagnosis, the type of cancer the person has, and other factors.

The National Institute of Health’s Surveillance, Epidemiology, and End Results Program (SEER) estimates that there will be 281,550 new cases of female breast cancer in the United States in 2021, and 43,600 people will as a result of breast cancer.

SEER also notes that from 2011–2017, the 5-year survival rate for breast cancer was 90.3%. That means that a person has a 90.3% chance of living another 5 years after their diagnosis, compared with a person who does not have breast cancer.

The average survival rates according to the stage at diagnosis, says SEER, were:

Stage5-year survival rate
Localized: Cancer has not yet spread beyond the breast90.3%
Regional: Cancer has reached nearby lymph nodes29%
Distant: Cancer has spread to other parts of the body6%
Unknown stage2%

However, the outlook varies widely, depending on the stage at diagnosis, the type of cancer a person has, treatment received, and other factors.

Learn more about survival rates for breast cancer.

The staging of breast cancer takes various factors into consideration, including how far cancer has spread, the size of any tumors, the type of tumor, and the grade, which affects how quickly cancer can grow.

Staging addresses the size and extent of the tumor, whether it has spread to nearby lymph nodes, and if it has metastasized, which means it affects more distant parts of the body.

The stage of breast cancer will help decide on treatment options and can give a guide to the outlook. It is worth noting, however, that each case is different. A doctor can help explain all the factors involved.

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