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Stages & Types of Breast Cancer

Breast cancer staging and prognosis

Breast cancer staging describes how far the cancer has spread within the breast and other parts of the body. It is an important factor in making treatment decisions.

Breast cancer staging is based on tumour size, the extent that cancer has spread to other parts of the body and other clinical factors. Your doctor will assign a stage to your cancer after your physical exam, mammogram, and other diagnostic tests, such as a biopsy (where the doctor removes tissue from the breast for further examination).

Breast cancer staging

Once the stage of the cancer has been determined, it is usually expressed as a number on a scale of 0 to IV:

  • Stage 0 refers to ‘pre-invasive’ breast cancers, including ductal carcinoma in situ (DCIS). This means that there are abnormal cells present, but they are contained inside the milk duct in the case of DCIS, or lobule (milk producing glands), in the case of lobular carcinoma in situ (LCIS). See Types of Breast Cancer.
  • Stage I and II are referred to as early breast cancer. Invasive breast cancer occurs when cancer cells within the milk duct or lobules break out into nearby tissue. Early breast cancer is invasive breast cancer that is contained within the breast. It may or may not have spread to the lymph nodes in the breast or armpit. Some cancer cells may have spread outside the breast and armpit area but cannot be detected.
  • Stage III is referred to as locally advanced breast cancer. This is an invasive breast cancer that has one or more of the following features:
    • May be large (typically bigger than 5 cm)
    • May have spread to several lymph nodes in the underarm area (axillary nodes), or other areas near the breast
    • May have spread to other tissues around the breast such as skin, muscle or ribs
  • Stage IV is called advanced or metastatic breast cancer. At this stage, the cancer has spread beyond the breast to other parts of the body. Common places of breast cancer spread include the bones, liver, lung, and brain. However, breast cancer may also spread to other organs.

Below are further details on the different stages of breast cancer:

Breast cancer stageSize of cancerHave cancer cells been found in...
...lymph nodes?...other parts of the body?
0Size not used for stage 0NoNo
I<2 cmNoNo
IIA<2 cmYes
(Category 1)
No
2–5 cmNoNo
No cancer found in breastYes
(Category 1)
No
IIB2–5 cmYes
(Category 1)
No
>5 cmNoNo
IIIA<2 cmYes
(Category 2)
No
2–5 cmYes
(Category 2)
No
>5 cmYes
(Category 1)
No
>5 cmYes
(Category 2)
No
No cancer found in breastYes
(Category 2)
No
IIIBAny size but the cancer has spread to nearby muscles and skinAny
(Can be yes or no)
No
IIICAny sizeYes
(Category 3)
No
IVAny sizeAny
(Can be yes or no)
Yes

Source: https://www.canceraustralia.gov.au/affected-cancer/cancer-types/breast-cancer/diagnosis/stages-breast-cancer

Breast cancer categories

If breast cancer has been found in the lymph nodes, the cancer can also be classified by the following categories:

  • Category 1:
    Breast cancer cells have been found in one to three lymph nodes in the armpit.
  • Category 2:
    Breast cancer cells have been found in:

    • 4–9 lymph nodes in the armpit, and the lymph nodes are also enlarged, and/or attached to each other or to nearby tissue; or
    • 1 or more lymph nodes under the breastbone, but not in any lymph nodes in the armpit.
  • Category 3:
    Breast cancer cells have been found in:

    • 10 or more lymph nodes in the armpit; or
    • 1 or more lymph nodes above or below the collarbone; or
    • 1 or more lymph nodes under the breastbone and 1 or more lymph nodes in the armpit.

TNM staging

Some doctors use the TNM system for staging breast cancer. In this system, letters and numbers are used to describe:

  • The size of the tumour (T stands for tumour)
  • The number of lymph nodes affected (N stands for nodes)
  • Whether the cancer has spread to other parts of the body (M stands for metastasis)

Numbers or letters following T, N, and M provide more details about each of these characteristics. In general, the higher the number or the later the letter following each component of TNM in the diagnosis, the more advanced the cancer.

In 2018, the TNM staging system was updated to include the following details to assist in classifying the cancer:

  • Oestrogen and progesterone receptor status – do the cancer cells have receptors for the hormones oestrogen and progesterone?
  • HER2 status – are the cancer cells making too much of the HER2 protein?
  • Tumour grade – a measurement of how much the cancer cells look like normal cells (See below)
  • Oncotype DX score (if applicable) – Oncotype DX score may be included as part of breast cancer staging for some cancers that are estrogen-receptor-positive, HER2-negative, and has not spread to the lymph nodes.

Grading for breast cancer

Tumour grading describes how active the cells are and how quickly the tumour is likely to grow. To determine tumour grade, a pathologist will study the tumour tissue removed during a biopsy under a microscope.

  • Grade 1 (low grade) Cancer cells look a little different to normal cells. These tumours are usually slow-growing.
  • Grade 2 (intermediate grade) Cancer cells do not look like normal cells. They tend to grow faster than grade 1 cancer cells.
  • Grade 3 (high grade) Cancers cells look very different from normal cells. They tend to grow and spread rapidly.

The breast cancer’s grade is used to help predict your likely outcome (prognosis) and determine which treatments are likely to be the most effective.

Prognosis of breast cancer

Prognosis refers to the probable or likely outcome of a disease (or the chance of recovery). Although tumour stage and grade are important, the physician will also take into account other considerations, such as whether certain molecular receptors are present (e.g. oestrogen or HER2 receptor), when determining a patient’s prognosis for breast cancer.

Breast cancer survival rates

While it is not possible to predict the exact course of disease for any individual, survival rates for breast cancer have improved remarkably over time due to earlier detection and improved treatment methods. The five-year survival rate is currently 91% on average for Australians diagnosed with breast cancer.

Whilst every case is different, breast cancer survival rates can also vary significantly depending on the stage of the cancer. According to data from the Australian Institute of Health and Welfare (AIHW), generally the earlier the stage when the breast cancer is first diagnosed, the higher the chance for better outcome.

Most patients with early or locally advanced breast cancer (stages 0-III) can be treated successfully. The poorest prognosis is for metastatic breast cancer (stage IV). However, there are different treatment options available, and there are people who continue to live full and meaningful lives, despite having metastatic breast cancer.

Research related to breast cancer classification and implications for clinical practice

Researcher: Dr. Sunil Lakhani, University of Queensland

Dr Lakhani recently published practice-changing findings that contributed to a new classification of a rare breast cancer, called metaplastic breast tumours, by the World Health Organisation. Learn more about his research here.