Staging of Breast Cancer

Alan Saj and Dr Lopamudra Das Roy

Published 2020

The stages of Breast Cancer are often misunderstood ranging from Stage I through Stage IV, but many of us don’t know that there is also a Stage 0. The different stages of Breast Cancer are determined by some characteristics, such as how large it is and whether or not it has hormone receptors. Also, knowing the stages of cancer is beneficial to you as it helps to figure out your prognosis, the likely outcome of the disease, decide on the best treatment options for you and determine if certain clinical trials may be a good option for you. (1)

TNM System

The breast cancer staging system, called the TNM system ensures that all doctors and treatment facilities are uniformly describing cancer so that the treatment results of all people can be compared and understood. (1)

The TNM staging system stands for Tumor, Node, Metastasis respectively.

T describes the size of the tumor (the swelling part of the body caused by abnormal growth of tissue).
N refers to the number of lymph nodes (small bean-shaped cluster of cells that filter your lymphatic fluid, which protects your body by destroying invaders) that have cancer.
M refers to whether cancer has spread to different parts of the body.

Another staging system used for all types of cancer groups is classified into five main categories:

In situ — Abnormal cells are present in its original location and has not spread to any other part of the body.
Localized — cancer is limited to its original place with no sign that it has spread.
Regional — In this stage, cancer has spread to nearby tissues, organs, or other nearby lymph nodes.
Distant — cancer has spread to distant parts of the body.
Unknown — Not enough information is there to figure out the stage of cancer.

STAGE 0 (1)

Stage 0 describes non-invasive breast cancers which shows no evidence of cancer cells breaking out from the part of the breast it started from and invading into another neighboring tissue.

(9)

STAGE I (1, 2, 3, 4, 5, 6)

Whereas stage 0 shows no evidence of breaking out from its original place, stage I describes cancer cells that invade normal surrounding breast tissue and is divided into two subcategories known as IA and IB.

Stage IA describes invasive breast cancer in which the tumor measures up to 2 centimeters (cm), and cancer has not spread outside the breast, thus, no lymph nodes are involved.

(10)

However, in stage IB there is no tumor in the breast. Instead, there are small groups of cancer cells — larger than 0.2 millimeters (mm) which are found in the lymph nodes.

STAGE II (1, 2, 7)

Similar to stage I of breast cancer, stage II is also divided into two subcategories known as IIA and IIB.

Stage IIA describes invasive breast cancer in which no tumor can be found in the breast, but cancer is found in the lymph nodes under the arm or the lymph nodes near the breast bone. (2)

(11)

However, if the cancer tumor measures between 2 and 5 cm and it has not spread to the lymph nodes, or any other part of the body away from the breast, and is also HER2-negative, meaning that breast cancer cells don’t have abnormal levels of HER2 proteins, then it is still likely to be classified as stage I.

There are 3 ways to determine if the cancer is in Stage IIB.

First, if the tumor is between 2-5 cm and small groups of breast cancer cells are found in the lymph nodes, then it is classified as stage IIB cancer.

It can also be classified as a Stage IIB cancer if it has spread to the axillary lymph nodes or to lymph nodes near the breastbone or if the tumor is larger than 5 cm but has not spread to the axillary lymph nodes.

STAGE III (1,2,3,8)

Unline Stage I and Stage II of breast cancer which was divided into two subcategories, Stage III of breast cancer is separated into three subcategories known as IIIA, IIIB, and IIIC.

Stage IIIA means one of the following:

no tumor is seen in the breast or the tumor may be any size; cancer is found in 4 to 9 lymph glands under the arm or in the lymph glands near the breastbone.

the tumor is larger than 5cm and small clusters of breast cancer cells are in the lymph nodes.

the tumor is more than 5cm and has spread into up to 3 lymph nodes in the armpit or to the lymph nodes near the breastbone.

(12)

Stage 3B means the tumor has spread to the skin of the breast or the chest wall. The chest wall means the structures surrounding and protecting the lungs, such as the ribs, muscles, skin, or connective tissues. (8)

“Stage 3C means the tumor can be any size, or there may be no tumor. But there is cancer in the skin of the breast, causing swelling or an ulcer and it has spread to the chest wall. (8) To be considered Stage 3C breast cancer it has to meet one of the following criteria-

Cancer cells have to spread to 10 or more lymph nodes
Spread to lymph nodes above or below the collarbone
The cells have to spread to the lymph nodes near the breastbone

STAGE IV (1,2,3)

In simple words, Stage 4 of cancer means that it has spread to other parts of the body. For example, cancer might have spread to the lungs, bones, liver, or the brain. This stage is also referred to as advanced cancer, secondary breast cancer, or metastatic breast cancer.

(13)

To sum it all up, It is very important to know the stages of breast cancer. Knowing the stages of cancer is beneficial to you as it helps to figure out your prognosis, the likely outcome of the disease, decide on the best treatment options for you and determine if certain clinical trials may be a good option for you.

References

Stages of Breast Cancer