Breast cancer is a type of cancer that begins in the breast tissue. Healthcare providers classify it into five stages, ranging from stage 0 to stage 4. These stages reflect how advanced the cancer is based on factors such as tumor size and the extent to which it has spread. Stage 0 is the earliest and least invasive, while stage 4 is the most advanced.
Understanding your cancer stage helps your healthcare team design the most effective treatment plan and predict your prognosis.
How Is Breast Cancer Stage Determined?
Once breast cancer is diagnosed, healthcare providers run several tests to determine its stage.
physical examination
This includes checking the breast and nearby areas and reviewing your medical history.
imaging tests
X-rays, CT scans, MRIs, PET scans, and ultrasounds help reveal whether cancer has spread.
blood tests
These tests check specific proteins and assess organ function, such as liver health.
biopsy
A biopsy removes a sample of tissue for examination. A sentinel lymph node biopsy (SLNB), which involves removing the first lymph node where cancer is likely to spread, is often used. The sample is checked for cancer cells and for levels of hormone receptors or HER2 proteins.
The TNM Staging System
The American Joint Committee on Cancer (AJCC) developed the TNM system, a common method used to classify cancer stages.
T (tumor)
Describes the size of the primary tumor and whether it has spread to nearby tissues. Ranges from 0 to 4.
N (nodes)
Indicates whether cancer has spread to nearby lymph nodes. This category also ranges from 0 to 3.
M (metastasis)
Shows whether the cancer has spread to distant organs.
Newer updates to this system also include:
hormone receptor status
Indicates the presence of estrogen or progesterone receptors in the cancer cells.
HER2 status
Reflects the amount of HER2 protein in the tumor.
grade
Evaluates how abnormal the cancer cells look under a microscope.
Doctors use all this information to assign a stage between 0 and 4. Since the staging process is complex, it's best to discuss your specific case with your medical team.
Summary of Breast Cancer Stages
| Stage | What It Means |
|---|---|
| Stage 0 | Noninvasive cancer confined to the breast lobules or ducts. |
| Stage 1 | Invasive cancer up to 2 cm in size, possibly present in nearby lymph nodes. |
| Stage 2 | Tumor is between 2 and 5 cm or has spread to up to three lymph nodes. |
| Stage 3 | Larger tumor or more extensive spread to lymph nodes or chest wall. |
| Stage 4 | Cancer has metastasized to distant organs like the liver, brain, or bones. |
Stage 0 Breast Cancer
This stage is noninvasive and often referred to as ductal carcinoma in situ (DCIS). The cancer is confined to the lining of the breast ducts or lobules.
symptoms
Usually, there are no noticeable symptoms. DCIS is often found through abnormal mammogram results.
treatment
Options may include breast-conserving surgery (partial mastectomy) and, in some cases, radiation therapy.
outlook
DCIS is highly treatable. Most people with this diagnosis are cured with proper treatment.
Stage 1 Breast Cancer
Stage 1 is divided into two substages:
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1A: Tumor up to 2 cm, not spread outside the breast.
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1B: Tumor is less than 2 cm but has small clusters of cells in nearby lymph nodes.
If hormone receptors are present, a tumor may still be considered stage 1A, as these make the cancer less aggressive.
symptoms
There may or may not be symptoms. Possible signs include:
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A lump in the breast
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Nipple discharge
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Skin dimpling
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Inverted nipple
treatment
Surgery is typically the first step. Chemotherapy or hormone therapy may also be recommended.
outlook
This is an early, localized stage of breast cancer. The five-year survival rate is nearly 100%.
Stage 2 Breast Cancer
Stage 2 breast cancer is invasive and broken into:
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Stage 2A: Tumor between 2 and 5 cm without lymph node involvement, or small tumors in lymph nodes only.
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Stage 2B: Tumor 2–5 cm with lymph node involvement, or larger than 5 cm without lymph node spread.
symptoms
Similar to stage 1, with possible changes in the breast, such as lumps or nipple discharge.
treatment
A combination of surgery, chemotherapy, and radiation is typically used with the intent to cure.
outlook
The five-year survival rate is around 93%.
Stage 3 Breast Cancer
This invasive cancer is categorized into:
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Stage 3A: Tumor larger than 5 cm with limited lymph node spread, or smaller tumor with more extensive lymph node involvement.
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Stage 3B: Cancer has reached the chest wall and may involve up to nine lymph nodes.
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Stage 3C: Tumor of any size that has spread to the skin, chest wall, and ten or more lymph nodes.
symptoms
Stage 3 often presents noticeable signs:
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Lumps
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Skin changes (dimpling, scaliness)
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Open sores
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Swelling
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Nipple discharge
treatment
Chemotherapy may be given before surgery to shrink the tumor, followed by surgery, radiation, and medications.
outlook
While more difficult to treat, the five-year survival rate is about 75%.
Stage 4 Breast Cancer
Also called metastatic breast cancer, this stage indicates cancer has spread to distant areas of the body.
symptoms
Vary based on where the cancer has spread:
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Bones: Pain, fractures
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Lungs: Shortness of breath
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Liver: Jaundice
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Brain: Headaches, seizures
treatment
Stage 4 is incurable, but treatment can ease symptoms, slow progression, and improve quality of life.
outlook
The five-year survival rate at this stage is around 32%.
Preventing or Slowing Progression
Breast cancer may progress over time if not treated, but progression rates vary depending on individual factors.
lifestyle strategies that may help include:
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Reaching and maintaining a healthy weight
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Eating a diet rich in whole foods and avoiding processed items
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Staying physically active
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Avoiding alcohol
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Quitting smoking
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Discussing supplements, like vitamin D, with your provider
These steps may help prevent progression or reduce recurrence risk.
Restaging
Cancer can be restaged after its initial diagnosis, especially if it returns or worsens.
restaging involves:
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Repeating imaging tests, biopsies, or lab work
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Assessing response to treatment
While restaging helps guide future care, the original stage remains the most critical for discussing survival statistics.
Life Through the Stages
Each stage of breast cancer brings different challenges and treatments. Managing side effects with your medical team is essential for maintaining quality of life.
additional support options include:
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Enrolling in clinical trials, especially in advanced stages
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Building a support system with family, friends, or others with breast cancer
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Participating in support groups
Living with breast cancer can be emotionally and physically demanding, but access to information, care, and community can make a significant difference.
A Quick Review
After a breast cancer diagnosis, staging is the next step to determine how far the disease has progressed. The TNM system is the most commonly used classification method and helps guide treatment and estimate prognosis. Each stage brings its own symptoms, treatment options, and survival rates. Working closely with your care team and maintaining a healthy lifestyle are key to managing breast cancer through every phase.
