Once you have been diagnosed, it’s important to know at what stage your cancer is. Knowing this will help you understand more about the type of breast cancer you have and help your doctor determine what kinds of treatments to consider.
 
Cancers are made of millions of cells that can travel to other parts of the body. Staging is a way of describing or classifying a cancer based on the extent of cancer in the body.


Stages of breast cancer :



Stage 0: Precancerous breast cancer (also known as non-invasive breast cancer, non-invasive carcinoma or carcinoma in situ)
 
Where the cancer is located: At this stage, the cancer is only found in the breast. There are two types of non-invasive breast cancer: lobular carcinoma in situ (LCIS) and ductal carcinoma in situ (DCIS).
 
LCIS is an overgrowth of cells that stay inside the lobule. It is not a true cancer but a warning sign of an increased risk for developing cancer in the future. DCIS is a non-invasive cancer that stays inside the milk duct.​

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Stages I and II: Early stage breast cancer (also known as invasive breast cancer).


Where the cancer is located: The cancer has spread beyond the original ducts/lobes and has moved to nearby tissue. 



  • Stage I – tumour measures up to 2 cm and no lymph nodes are affected.

  • Stage II – tumour measures greater than 2 cm but less than 5 cm OR the tumour has spread to one to three lymph nodes on the same side as the breast cancer.

Stages IIIA and IIIB: Locally advanced breast cancer (also known as late stage breast cancer).


Where the cancer is located: The cancer has spread to four or more lymph nodes and/or the tumour in the breast measures more than 5 cm.

Stage IV: Advanced stage breast cancer (also known as metastatic breast cancer or distant metastatic breast cancer).

Where the cancer is located: The cancer has spread beyond the breast, underarm and internal mammary node (these nodes sit between the breast and sternum bone) to other parts of the body. For example, it may have spread to the lungs, liver, bone, brain or other distant site.



Tumour grades

A tumour grade indicates how quickly the tumour is likely to grow and spread. Tumours can be low-grade or high-grade based on the degree of differentiation and growth rate.


  • Low-grade cancer cells are slower growing.

  • Moderate-grade cancer cells have features in between low-grade and high-grade cancer cells.

  • High-grade cancer cells are faster growing and spread sooner.


Grade 1, 2, 3: refers to the level of abnormality in the cancer cell.


  • The lower the number, the lower the grade. For example, in Grade 1 tumours, the tumour cells are the most similar to normal cells. Higher grades do not look like normal cells. Grade 3 tumours tend to grow rapidly and spread faster than lower grades.


Tumours can be benign or malignant.


Malignant tumours can cause trouble for the part of your body in which the tumour formed as well as other areas of the body that it may spread to. The process by which cells spread to other areas of the body to form tumours is known as metastasis. Metastatic growths of tumours in your body’s organs are more serious than the original tumour because they are harder to treat.


Cancer that spreads from the breast to other areas of your body is still called breast cancer. For example, if your breast cancer spreads to your bones, it is not called bone cancer – it is metastatic breast cancer involving the bone.


The most common symptom of breast cancer is a new lump or mass. Other symptoms may include:


  • Swelling of all or part of a breast (even if no distinct lump is felt).

  • Skin irritation or dimpling.

  • Breast or nipple pain.

  • Nipple retraction (turning inward).

  • Redness, scaly appearance, or thickening of the nipple or breast skin.

  • A nipple discharge other than breast milk.


It is important to have any new breast mass, lump, or changes checked by your doctor.



Early breast cancer

Early breast cancer (eBC) is defined by:
✓ Size: The tumour is smaller than 5 cm
✓ Spread: The cancer is contained in the breast and has not spread to other parts of the body (except the lymph nodes – and no more than 3 of them).


Stages 1A, 1B and 2A are considered early breast cancer.

  • 1A: The tumour is smaller than the approximate size of a peanut (2 cm or smaller) and has not spread to the lymph nodes.
  • 1B: Lymph nodes have cancer evidence with small clusters of cells between the approximate size of a pinprick to the approximate width of a grain of rice
  • 2A: No actual tumour is associated with the cancerous cells and less than four auxillary lymph nodes have cancer cells present OR
  • The tumour is less than 2 cm and less than four auxillary lymph nodes have cancer cells present OR
  • The tumour is between 2 and 5 cm and has not yet spread to the lymph nodes


Among those first diagnosed with early stage breast cancer, approximately 1/3 of patients will experience recurrence (the cancer will come back) or metastatic cancer.


Advanced breast cancer


Advanced breast cancer (aBC) is also called metastatic breast cancer, and is defined as:

  • Size: The tumour is larger than 5 cm.
  • Spread: The cancer may have spread to the skin, the muscles of the chest wall or to more than 3 lymph nodes.


Stages 2B, 3A, 3B, 3C and 4 are considered advanced breast cancer.

  • 2B:The tumour is larger than 2 cm but not more than 5 cm, and has also spread to 1 to 3 axillary lymph nodes (internal mammary lymph nodes or both areas), OR
  • The tumour is larger than 5 cm
  • 3A: The tumour is 5 cm or smaller, or no tumour can be seen in the breast. Cancer cells are found in 4 to 9 axillary lymph nodes, or in internal mammary lymph nodes but not in the axillary lymph nodes, OR
  • The tumour is larger than 5 cm, and the cancer has also spread to 1 to 9 axillary lymph nodes or to internal mammary lymph nodes.
  • 3B: The tumour has grown into the muscle of the chest wall or the skin, or both. The cancer may have also spread to 1 to 9 axillary lymph nodes and internal mammary lymph nodes, or it may have spread to 1 to 3 axillary lymph nodes and internal mammary lymph nodes, OR
  • Inflammatory breast cancer
  • 3C: The cancer has spread to 10 or more axillary lymph nodes or to lymph nodes below the collarbone, OR
  • The cancer has spread to more than 3 axillary lymph nodes and internal mammary lymph nodes, OR
  • The cancer has spread to lymph nodes above the collarbone
  • 4: The cancer has spread to other parts of the body. This is also called metastatic breast cancer.


While advanced breast cancer generally describes cancers that have spread beyond the breast and lymph nodes, there is another type of advanced cancer called inflammatory breast cancer. Inflammatory breast cancer can affect the skin, muscles of the chest wall and lymph nodes as well as the breast itself. Because it has not spread, doctors call it “locally advanced breast cancer.”
  

“Will the cancer come back?”: Risk of recurrence
 
Just as every woman is different, it is hard to know with certainty whether your cancer will return or go into remission. Doctors use key pieces of information to determine if the risk of your cancer coming back is high or low.

Here are some of the things that your doctor will consider:


  • What is the size of the tumour?
  • What is the grade of the tumour?
  • What is the hormone receptor status of the cancer cells?
  • Has the patient tested negative or positive for HER2?
  • What is the nodal status? Status can be either positive or negative depending if the cancer has spread to the lymph nodes.
  • Has the cancer grown into lymph vessels, blood vessels, or both?


What are the treatment options?


Depending on the level of risk, your doctor may offer you something called adjuvant therapy, to help prevent cancer from returning.

Keep in mind that for most patients with early stage breast cancer, their treatment will be successful, and remove the cancer from the body. However, for about 1 in 3 patients with early stage breast cancer, the cancer will progress to advanced stages (“aBC”) or metastatic cancer. For those patients who have been diagnosed with aBC, the goal is two-fold: help them live longer, and maintain a good quality of life.



Prognostic Factors


Low risk of recurrence
 
Breast cancer has a low risk of recurrence when all of the following apply:


  • The tumour is smaller than 1 cm in diameter.
  • The cancer cells have receptors for both estrogen and progesterone (they are hormone-receptor positive).
  • The cancer is grade 1 (low grade).
  • The cancer has not spread to lymph vessels or blood vessels in the breast tissue.


Moderate risk of recurrence

Breast cancer has a moderate, or intermediate, risk of recurrence when all of the following apply:


  • The tumour is up to 5 cm in diameter.
  • The cancer cells are hormone receptor positive.
  • The cancer is grade 1 (low grade) or grade 2 (intermediate grade).
  • The cancer has spread to only 1–3 lymph nodes.
  • The cancer has not spread to lymph vessels or blood vessels in the breast tissue.


High risk of recurrence


 
Breast cancer has a high risk of recurrence when any of the following apply:


  • The tumour is larger than 5 cm in diameter.
  • The cancer cells are triple negative, which means they don’t have receptors for estrogen or progesterone and they don’t have extra copies of the HER2 gene.
  • The tumour is high grade (grade 3).
  • The cancer has spread to lymph vessels or blood vessels in the breast tissue.
  • The cancer has spread to 4 or more lymph nodes.
  • The cancer has spread to muscles on the chest or the skin of the breast. 
  • The cancer is inflammatory breast cancer. 
  • The cancer cells are HER2 positive.