The 4 stages of breast cancer
The four stages of breast cancer include
- Stage I: It is divided into two groups.
- Stage II: It is divided into two groups.
- Stage III: Cancer hasn’t spread to bones or organs. However, it is considered an advanced stage. There are three groups.
- Stage IV: Breast cancer cells have spread far away from the breast and lymph nodes around it.
- Clinical staging: Based on the results of tests done before surgery, which may include physical examinations, mammograms, ultrasound, and magnetic resonance imaging (MRI) scans.
- Pathological staging: Based on what is found during surgery to remove breast tissue and lymph nodes.
In both the staging systems, seven key pieces of information are used.
- T (tumor): It refers to the size of the original tumor.
- N (node): It describes whether cancer has spread to the lymph nodes.
- M (metastasis): It refers to the spreading of cancer to other parts of the body.
- Estrogen receptor (ER) status: It refers to the presence of a protein called estrogen receptor in cancer.
- Progesterone receptor (PR) status: It defines whether cancer has a protein called a progesterone receptor.
- HER2 status: It assesses if cancer is producing too much of a protein called HER2 (human epidermal growth factor receptor 2).
- Grade of cancer (G): It refers to how close cancer cells appear like normal cells.
A number (0-4) or the letter X is allocated to each factor. A higher number means the cancer is more advanced. For instance, a T1 score refers to a smaller tumor than a T2 score. The letter X indicates that the information could not be assessed.
Table. The characteristics of breast cancer according to the TNM staging system
|Stages||T Category||N Category||M Category|
|X||The primary tumor cannot be assessed.||The lymph nodes cannot be assessed.||Distant spread cannot be evaluated.|
|0||No evidence of cancer in the breast.||
There are two possibilities:
|No distant spread|
Cancer is confined within the ducts of the breast tissue and has not spread into the nearby tissue. There are two types:
|0 (i+)||-||-||No clinical or radiological evidence of metastases. Although there is microscopic evidence of cancer cells in the blood, bone marrow, or other lymph nodes that are no larger than 0.2 mm.|
The tumor in the breast is 20 mm or smaller in size at its widest area. There are four substages:
Cancer has spread to one or three lymph nodes in the armpit.
|Evidence of metastasis to another part of the body, which means breast cancer cells are growing in other organs.|
|II||The tumor is between 20 and 50 mm.||Cancer has spread to four to nine lymph nodes.||-|
|III||The tumor is larger than 50 mm.||Cancer has spread to 10 or more lymph nodes.||-|
The tumor falls into one of the following groups:
T4a means the tumor has grown into the chest wall.
T4b is when the tumor has grown into the skin.
T4c is cancer that has grown into the chest wall and the skin.
T4d is inflammatory breast cancer.
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American Cancer Society. Breast Cancer Stages. https://www.cancer.org/cancer/breast-cancer/understanding-a-breast-cancer-diagnosis/stages-of-breast-cancer.html