Breast Cancer Stages
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Understand What Your
Breast Cancer Stage
Means for Treatment

Just how individuals are unique, every case requires a full evaluation and personalized assessment to develop the best treatment plan for you. Even cancers in the same stage may require a different approach due to the type found in the cells and where it has spread. Before you choose a treatment plan, it’s good to familiarize yourself with your type, stage and treatment options available, so you feel more confident. You and your doctor will also want to consider other personal factors that could influence your decisions. Some of these include age, health, genetic mutations, personal risk factors, thoughts on breast reconstruction and future health concerns. If you have time, getting a second opinion is recommended to see if another doctor has access to newer technologies, more experience in treating your type of cancer or simply feels like a better fit for your lifestyle.

Determining the Stage of Your Breast Cancer

After receiving a diagnosis, the first question many people ask is, “What stage is it?” While the answer may be simple, there are many factors that go into the determination. This process is called staging and the information below briefly describes what and how doctors evaluate the cancer. Ultimately, knowing this will help them recommend the most effective treatment plan.


TNM Staging

This classification is made up of three different measurements, each represented by a letter and number. “T” refers to the tumor and is followed by a number from 0 to 4. The higher the number, the larger the tumor and/or extent it has spread. “N” is derived from lymph nodes, which are meant to catch cancerous cells before traveling to other parts of the body. A number from 0 to 3 will be assigned based on if, and how many, lymph nodes are affected. The “M,” followed by a 0 or 1, states whether the cancer has spread or metastasized to distant organs (i.e. lungs, liver or bones).


ER, PR & HER2 Status

The presence of certain hormones plays an important role in determining the proper treatment and assessment of how the cancer cells will grow and/or can be stopped. If your cancer is estrogen receptor-positive (ER-positive), progesterone receptor-positive (PR-positive) and/or makes too much of the HER2 protein (HER2-positive), it means you’re a likely candidate for hormone therapy. If the opposite is true, it means you’re ER-negative, PR-negative and/or HER2-negative and hormone therapy will have no effect on your cancer. Triple-negative breast cancers occur in those who are ER-negative, PR-negative and HER2-negative. In these cases, the cancer tends to grow and spread faster than other types.



Grading takes place post-biopsy to classify the aggressiveness of the cancer or how quickly the cancer may grow and spread. Your pathologist will study tissue samples to identify cell patterns and amount of cellular differentiation from normal breast cells. Grade 1 cancer cells are small, uniform and usually slow-growing. Grade 2 cancer cells are slightly bigger than normal cells and vary in shape. Grade 3 cancer cells tend to be faster-growing and look distinctly different than normal cells. Rather than 1, 2 or 3, non-invasive Stage 0 breast cancers are defined as low, medium or high grade.

Breast Cancer Stages and Relative 5-Year Survival Rates*


100%            100%            93%           72%              22%

Stage 0       Stage I        Stage II        Stage III       Stage IV

*Percentages are based on how many people live for at least 5 years after diagnosis


Stage 0 Breast Cancer

You’ll often hear of cancer that has started in the milk ducts or milk glands as “in situ,” meaning it has stayed “in the original place.” Cancer at this stage is considered non-invasive because there’s no evidence of cancerous or other abnormal cells existing elsewhere.


Ductal carcinoma in situ (DCIS) Abnormal cells are found in the lining of the milk ducts.

Lobular carcinoma in situ (LCIS) Technically not cancer, but abnormal cell growth has been found in the lining and has a high risk of turning into cancer. 


Stage I Breast Cancer

Cancer at this stage is now considered invasive because the tumor cells have started to attack healthy breast tissue. However, it’s classified as “early stage,” due to the cancer being contained in a small area. Where is determined by labeling it Stage IA and Stage IB.


Stage IA The tumor has spread to the fatty breast tissue but is no larger than a shelled peanut.

Stage IB A tiny amount of cancer cells can be found in a few lymph nodes.


Stage II Breast Cancer

At this stage, the cancer is considered localized. The cancer has grown and/or spread to a limited region of the breast and lymph nodes. Like Stage I, Stage II is further classified into Stage IIA and Stage IIB to more accurately pinpoint its location.


Stage IIA The tumor is the size of a grape and has spread to the lymph nodes under the arm or is 20 to 50 millimeters but hasn’t spread to the lymph nodes.

Stage IIB The tumor is the size of a walnut and has spread to 1 to 3 nearby lymph nodes or is as big as a lime and has not spread to any lymph nodes.


Stage III Breast Cancer

While the cancer has spread regionally, it hasn’t spread to the bones or surrounding organs. However, the cancer is now considered advanced and harder to fight. This stage is broken down into three sub-categories to better shape your treatment plan.


Stage IIIA Tumor cells are found in 4 to 9 nearby lymph nodes or the tumor is larger than 50 millimeters and has spread to 1 to 3 lymph nodes.

Stage IIIB Tumor cells have spread to the chest wall behind the breast and may have also spread to or broken through the skin or spread to as many as 9 lymph nodes under the arm or near the breastbone.

Stage IIIC The cancer has now spread to one of the following places: 10 or more underarm lymph nodes, lymph nodes above or below your collarbone, a mixture of underarm and near the breastbone lymph nodes or the skin.


Stage IV Breast Cancer

At this stage, the cancer is now called “metastatic breast cancer,” meaning it has spread far from the breast and into the bones, lungs, liver and/or brain. As of right now, there is no known cure, but treatment can help alleviate symptoms and prolong life.

Breast Cancer Treatment Options Based on Stage and Types


Stage 0 Breast Cancer Treatment

Even though the cancer is non-invasive, immediate treatment is recommended to prevent it from spreading outside of the lining of your milk ducts. Surgery, radiation or a combination of the two is often used to remove the tumorous cells. Typically, systematic therapy or drug therapy is not needed. Personal risk factors might influence this treatment plan.


Stage I Breast Cancer Treatment

Surgery is the main treatment option, but the decision to get a lumpectomy or mastectomy depends on a variety of medical and personal factors. A lumpectomy removes a smaller portion of breast tissue, while a mastectomy involves the removal of all the breast tissue in one or both breasts. During either surgery, your lymph nodes will also be checked with a sentinel biopsy or axillary lymph node dissection to make sure the cancer hasn’t spread. After surgery, radiation or proton therapy is usually given to lower the chance of the cancer returning. If you have an ER-positive or PR-positive breast cancer, you may receive hormone therapy for at least 5 years. For tumors larger than 1cm or tumors with unfavorable features (i.e. fast-growing, ER-negative, PR-negative or HER2-positive), chemotherapy may also be recommended.


Stage II Breast Cancer Treatment

Similar to Stage 1, surgery is often the first treatment option to remove the breast tissue and check the lymph nodes. In some cases, a lumpectomy may no longer be an option. If that’s the case, a mastectomy will be performed. Radiation or proton therapy will be used after surgery or chemotherapy for those who need it post-surgery. Some doctors recommend chemotherapy or hormone therapy before the operation to shrink the tumor. The combination and use of different drug therapies are typically based on your age, tumor results and hormone receptor and HER2 statuses.


Stage III Breast Cancer Treatment

In some cases, your cancer will be treated with drug therapy before surgery to shrink the tumor. If the tumor doesn’t shrink enough, a lumpectomy will no longer be sufficient, and a mastectomy will need to be performed to remove all of the breast tissue. Nearby lymph nodes will also be checked with an axillary lymph node dissection. Due to the tumor size and growth into nearby tissues, many choose to start with a mastectomy. If chemotherapy is not needed after surgery, radiation or proton therapy is a common next step. Other drug treatments might be recommended at all or different stages of the treatment plan. The specific therapies rest largely on your age, tumor results, desire to shrink the tumor first and hormone receptor and HER2 statuses.


Stage IV Breast Cancer Treatment

Once the cancer has moved to this stage, it’s considered incurable. However, there are treatments that can shrink tumors, slow the growth of cancerous cells, improve symptoms and help prolong life. The main treatment for metastatic cancer is usually a combination of systematic or drug therapies such as hormone, chemo and targeted. Surgery and/or radiation may also be recommended to prevent, treat and/or address complications caused by the cancer. Many choose to continue treatment until the cancer stops responding to treatment, they don’t feel the treatment-related side effects are worth it or various other personal reasons.


Inflammatory Breast Cancer Treatment

Depending on whether it has spread to other parts of the body, this rapidly-growing type of breast cancer is considered either Stage III or Stage IV. While one of the rarer types, inflammatory breast cancer occurs when the cancer cells block the lymphatic vessels in the breast skin. As a result, the breast becomes visibly red, swollen, tender and warm. Most treatment plans involve a combination of drug therapies, radiation and surgery. Chemotherapy is commonly used first, as it can enter the bloodstream and destroy cancer cells throughout the body. If those drugs work, surgery is performed next, followed by radiation and possibly another round of chemo.


Triple Negative Breast Cancer Treatment

Chemotherapy is usually the standard treatment because these cancers tend to grow and spread faster than most. Since the cancer cells in these cancers don’t have hormonal receptors and lower amounts of HER2, hormone therapy isn’t an option. However, targeted therapy and immunotherapy can be effective. Radiation may also be recommended. Newer treatments are also available through clinical trials for those wanting access to the latest medical advancements.


Consider Choosing Proton Therapy Radiation

Proton therapy continues to gain popularity for its ability to precisely control the treatment dose, so it targets the tumor and spares healthy tissues and organs. By reducing the radiation exposure to the rest of your body, you may lower your risk of cardiac events, lung cancer and pneumonitis later in life. This treatment has also been shown to result in strong cure rates, reduced side effects and improved long-term outcomes. Unlike standard radiation, proton therapy is also an option for treating recurrent cancer.

Explore Proton Therapy for Breast Cancer Treatment