Understanding the Stages of Breast Cancer

A cancer diagnosis is scary. Even more so when you don’t know the terminology that’s used to describe your illness. 

To help you better understand your diagnosis, or that of a loved one, we’ve put together this guide to the stages of breast cancer, plus their treatments and survival rates.

Related read: Debunking the Most Common Breast Cancer Myths

Understanding the Stages of Breast Cancer

The different stages of breast cancer and what they mean

Staging is a way of describing how extensive a case of breast cancer is in a patient. 

Categorizing breast cancer into different stages does two things. First, it provides useful, standardized information about the illness to doctors and patients. This, in turn, aids in identifying the best path of treatment and understanding the likely outcome of treatment.

Breast cancer stages are broadly divided into two types: TNM and stage groups.

TNM breast cancer staging

Short for tumor, node, metastasis, the TNM stages of breast cancer are used by doctors to describe the progression of the illness. The categorisation runs from stage 0 (non-invasive ductal carcinoma in situ) to stage 4 (invasive breast cancer).

When it comes to these stages of breast cancer, symptoms vary depending on the area in which the cancer is found after breast cancer screening.


T, or tumor, is used to describe where the tumor is found, its size and the biomarkers it is triggering. There are five substages here:

    • TX: The primary tumor cannot be evaluated 

    • T0: No evidence of cancer in the breast tissue

    • Tis: Carcinoma in situ (in the milk ducts, but not breast tissue)

    • T1: A tumor of 20mm of less is present. Stage T1 has four subcategories based on the tumor’s size, from less than 1mm to 20mm.  

    • T2: The tumor is between 20mm and 50mm

    • T3: The tumor is larger than 50mm

    • T4: Cancer has spread to the chest wall and/or skin, or has become inflammatory


The node staging is used to describe the stages of breast cancer symptoms related to the lymph nodes in the breast. There are four stages here:

    • NX: Nodes not evaluated

    • N0: Either no cancer in the nodes or areas smaller than 0.2mm

    • N1: Evidence of cancer in one to three auxiliary or mammary lymph nodes

    • N2: Cancer has spread to four to nine axillary lymph nodes, or it appears in internal mammary nodes but not the axillary

    • N3: Cancer is present in 10 or more axillary lymph nodes, clavicle nodes and possibly internal mammary nodes


Metastasis focuses on the spread of cancer. This metric considers whether cancerous cells can be found elsewhere in the body, either through clinical or pathological diagnosis. Again, there are various substages of metastasis:

    • MX: Distant spread cannot be evaluated

    • M0: There is no evidence of metastasis

    • M0 (i+): No clinical evidence of metastasis exists, but there is pathological evidence in blood, bone marrow or other lymph nodes

    • M1: There is evidence of cancer cells elsewhere in the body

Stage groups

Stage groups combine the TNM three stages of breast cancer symptoms to describe the tumor’s location and size as well as whether it has spread to other parts of the body.

Stage 0 indicates that cancer cells are present only in the milk ducts. Following this, stage I breast cancer indicates a small tumor that is either invasive, present in the lymph nodes (measuring 0.2–2mm) or in the breast tissue but smaller than 20mm.

Tumors ranging from less than 20mm with cancer in one to three of the axillary lymph nodes to those of more than 50mm that do not affect the axillary nodes can be categorized as stage II breast cancer.

Stage III describes a progression in size and prevalence of the cancer in the breast from stage II. The cancer may be present in four to 10 or more axillary lymph nodes as well as the mammary lymph nodes and clavicle or it may exceed 50mm. 

Up until this point, the cancer has been localized in the breast. A diagnosis of stage IV, or metastatic cancer, indicates that the cancer has spread to other parts of the body.

Stages of breast cancer and treatment

There are both surgical and non-surgical interventions that can be used to treat breast cancer at its different stages. Generally, the stage groups will be used to determine the best course of action.

Stage 0

Surgical interventions, including breast-conserving surgery (BCS) and mastectomy, are the most common treatments for patients with stage 0 breast cancer. This treatment is usually followed by hormonal therapy to reduce the chance of recurrence where the tumor is hormone-receptor positive.

Stages I to III

The following three stages of breast cancer treatment plans usually involve local therapies (surgery and radiation). You may also be given chemo or other drug therapies before or after your surgery.

    • Stage 1: Surgery is the most common treatment for stage 1 breast cancer. It’s usually combined with radiation therapy.
    • Stage 2: Again, surgical interventions are the most common way of treating stage 2 cancer. Most women with this stage of cancer receive chemotherapy either before or after their BCS or mastectomy.
    • Stage 3: Women with stage 3 breast cancer are usually given neoadjuvant (before surgery) chemotherapy followed by either a BCS or full mastectomy. Some patients may be able to have surgery prior to receiving chemotherapy (adjuvant therapy).

Stage IV

Unfortunately, stage IV cancer is considered incurable. Once cancer is detected in other parts of the body, drug therapies become the main course of treatment. Surgery and radiation may also be possible in some cases.

Hormone and immunotherapy, chemotherapy, targeted drug therapy – or a combination of these – are used to fight the illness, slowing the growth of tumors, improving symptoms and possibly extending the lives of patients.

Breast cancer stages survival rate

Fortunately, the five-year survival rates for breast cancer are some of the highest out of the various cancer types. Research from the Nuffield Trust indicates that 86.3% of women in the UK have a five-year survival rate (i.e. they survived for at least five years after diagnosis or the start of treatment. 

According to the American Cancer Society, localized breast cancer, which has not spread outside of the breast, has a 99% five-year survival rate. Regional breast cancer, where cells are found in nearby structures of lymph nodes, and metastatic cancer have a five-year survival rate of 86% and 29%, respectively.

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