Breast cancer

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Staging breast cancer

Staging is a way of describing or classifying a cancer based on the extent of cancer in the body. Extent includes the size of the tumour and where the cancer is in the body. Your healthcare team uses the stage to plan treatment and estimate your prognosis.

The most common staging system for breast cancer is the TNM system. Each stage is given a number from 0 to 4. Stages 1 to 4 are usually given as the Roman numerals I, II, III and IV. Generally, the higher the number, the more the cancer has spread.

Breast cancer groupings

Sometimes doctors group the different stages of breast cancer in the following ways.

Early stage breast cancer means that the tumour is smaller than 5 cm and the cancer has not spread to more than 3 lymph nodes. It includes stages IA, IB and IIA.

Locally advanced breast cancer means that the tumour is larger than 5 cm. The cancer may have spread to the skin, the muscles of the chest or more than 3 lymph nodes. It includes stages IIB, IIIA, IIIB and IIIC. Inflammatory breast cancer is also considered locally advanced breast cancer.

Advanced, or metastatic, breast cancer means that the cancer has spread to other parts of the body. It is stage IV breast cancer.

TNM descriptions

T describes the size of the primary tumour. It also describes if the tumour has grown into tissues around the breast. T is usually given as a number from 1 to 4. A higher number means that the tumour is larger. It may also mean that the tumour has grown deeper into nearby tissues.

 

N describes whether or not cancer has spread to lymph nodes around the breast. N0 means the cancer hasn’t spread to the lymph nodes. N1, N2 or N3 means cancer has spread to lymph nodes. N1 to N3 can also describe the number of lymph nodes that contain cancer, as well as their location. The number of lymph nodes with cancer is known after surgery.

M describes whether or not the cancer has spread, or metastasized, to other parts of the body. M0 means that cancer has not spread to other parts of the body. M1 means that it has spread to other parts of the body.

Stage 0 (carcinoma in situ)

TNMDescription

Tis

N0

M0

Cancer is found only in the ducts, lobules or nipple.

Tis (DCIS) is ductal carcinoma in situ.

Tis (LCIS) is lobular carcinoma in situ.

Tis (Paget) is Paget disease when there isn’t invasive ductal carcinoma or ductal carcinoma in situ (DCIS) in the breast.

Stage IA

TNMDescription

T1

N0

M0

The tumour is 2 cm or smaller in size.

Stage IB

TNMDescription

T0 or T1

N1mi

M0

One of the following applies:

  • No tumour is found in the breast.
  • The tumour is 2 cm or smaller.

Cancer cells have spread to the lymph nodes under the arm (called the axillary lymph nodes). The area within each lymph node that has cancer cells in it is no larger than 2 mm (mi).

Stage IIA

TNMDescription

T0

N1

M0

No tumour is found in the breast.

Cancer is found in axillary lymph nodes.

T1

N1

M0

The tumour is 2 cm or smaller.

Cancer is found in axillary lymph nodes.

T2

N0

M0

The tumour is larger than 2 cm, but it is no larger than 5 cm.

Stage IIB

TNMDescription

T2

N1

M0

The tumour is larger than 2 cm, but it is no larger than 5 cm.

Cancer is found in the axillary lymph nodes.

T3

N0

M0

The tumour is larger than 5 cm.

Stage IIIA

TNMDescription

T0

N2

M0

No tumour is found in the breast.

Cancer has spread to the axillary lymph nodes, or cancer is found in the lymph nodes inside the breast tissue (called the internal mammary nodes) if there is no cancer found in the axillary lymph nodes. The lymph nodes are stuck, or fixed, to the surrounding tissues.

T1

N2

M0

The tumour is 2 cm or smaller.

Cancer has spread to the axillary lymph nodes, or cancer is found in the internal mammary lymph nodes if there is no cancer found in the axillary lymph nodes. The lymph nodes are fixed to the surrounding tissues.

T2

N2

M0

The tumour is larger than 2 cm, but it is no larger than 5 cm.

Cancer has spread to the axillary lymph nodes, or cancer is found in the internal mammary lymph nodes if there is no cancer found in the axillary lymph nodes. The lymph nodes are fixed to the surrounding tissues.

T3

N1 or N2

M0

The tumour is larger than 5 cm.

Cancer has spread to the axillary lymph nodes, or cancer is found in the internal mammary lymph nodes if there is no cancer found in the axillary lymph nodes. The lymph nodes may or may not be fixed to the surrounding tissues.

Stage IIIB

TNMDescription

T4a, T4b or T4c

N0, N1 or N2

M0

T4a: The tumour has grown into the muscles on the chest.

T4b: The tumour has grown into the skin of the breast.

T4c: The tumour has grown into both the muscles on the chest and the skin of the breast.

The cancer has spread to the axillary lymph nodes, or cancer is found in the internal mammary lymph nodes if there is no cancer found in the axillary lymph nodes. The lymph nodes may be fixed to the surrounding tissues.

T4d

Stage IIIC

TNMDescription

any T

N3

M0

The tumour can be any size.

One of the following applies:

  • Cancer has spread to the lymph nodes below the collarbone, with or without spread to the axillary lymph nodes.
  • Cancer has spread to both axillary and internal mammary lymph nodes.
  • Cancer has spread to lymph nodes above the collarbone, with or without spread to the axillary lymph nodes or the internal mammary lymph nodes.

Stage IV

TNMDescription

any T

any N

M1

The tumour can be any size. It may have grown into surrounding tissues.

The cancer may have spread to lymph nodes.

The cancer has spread to other parts of the body (called distant metastasis), such as the bones, liver, lungs or brain.

Recurrent breast cancer

Recurrent breast cancer means that the cancer has come back after it has been treated. If it comes back in the same place that the cancer first started, it’s called local recurrence. If it comes back in tissues or lymph nodes close to the primary tumour, it’s called regional recurrence. It can also recur in another part of the body, which is called a distant metastasis, or a distant recurrence.

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