Breast cancer staging is a way of finding out how far cancer has spread, the size of the tumor, and the lymph nodes’ situation in the breast. Five stages of breast cancer range from 0-4, written as 0, Ⅰ, Ⅱ, Ⅲ, and Ⅳ. The number of stages determines the severity of cancer, and the higher number of stages indicates more cancer availability in the breast. American Joint Committee on Cancer (AJCC) has developed the TNM staging system to determine the stage of breast cancer.
TNM staging system
- TNM is the most common tool doctors use to determine the cancer stage. TNM stands based on its letters as T stands for tumor, N stands for nodes, and M stands for metastasis. These three tumors, node, and metastasis, are important factors in determining the severity of cancer.
- Letter T describes the size, location, and situation of the tumor in the breast. It is further divided into subgroups of TX, T0, T1, T2, T3, and T4 for more detailed information on the cancer stage.
- Letter N describes the situation of the node in the breast. It also tells whether cancer has reached the node or not. It is also further subdivided into NX, N0, N1, N2, and N3 to get detailed information on how far cancer has spread.
- Letter M stands for metastasis which describes whether cancer has gone to other parts of the body or not. It is also divided into MX, M0, and M1 subgroups.
Stages of the breast cancer
There are following five stages of breast cancer;
Stage 0 breast cancer:
Stage 0 is the non-invasive type of breast cancer because it is present in the ducts and lobules of the breast, such as (DCIS) ductal carcinoma in situ. At this stage, the cancerous cells are present only in the breast and do not spread out to the body’s other parts.
Stage Ⅰ breast cancer:
Stage Ⅰ is invasive breast cancer. The cancer cells are normal at this stage, but they have also spread into the whole breast. It is further subdivided into two types:
- Stage ⅠA: The length of this tumor is almost 2 centimeters (cm). It does not spread to the lymph nodes. (T1, N0, M0)
- Stage IB: The length of this tumor ranges from 0.22m to 2mm, and it is found in the lymph nodes of the breast.
Estragon- receptors positive and progesterone- receptor-positive are also included in stage ⅠA.
Stage Ⅱ breast cancer:
Stage Ⅱ of breast cancer is more critical than stage Ⅰ as cancer becomes larger in this stage and it also spreads to lymph nodes. It is invasive breast cancer that is sub-divided onto two types:
- Stage ⅡA: In stage Ⅱ, the tumor is not present in the breast, but it is spread from one to three axillary lymph nodes in the armpits. The size of the tumor is from 2cm to 5cm. There are two chances in this stage; one is that the size of the tumor is smaller than 20mm and it has spread to the lymph nodes (T1, N1, M0), or the size of the tumor is 2-5cm, and it has not spread to the lymph nodes, and it is HER2-negative, estrogen receptor-positive and progesterone receptor-negative (T2, N0, M0).
- Stage ⅡB: There are also two conditions in this stage, first is that the size of the tumor is 2cm to 5cm, and it has spread to axillary lymph nodes; then, the cancer is HER2-negative, and it is estrogen receptor-positive and progesterone receptor-positive(T2, N1, M0). The second is that the tumor size is more significant than 5cm and has not spread to the axillary lymph nodes (T3, N0, M0).
Stage Ⅲ breast cancer:
In stage Ⅲ, cancer spreads to several lymph nodes, and it is more significant than in stages Ⅱ and stage Ⅰ. It is invasive breast cancer that is life-threatening. Stage Ⅲ has the following three types:
- Stage IIIA: In this stage, there can be a tumor in the breast, and the tumor has spread from four to nine lymph nodes, but it has not spread to the other parts of the body (T0, T1, T2, or T3; N2; M0) and it may have the tumor that is larger than 50mm then it has spread to the other parts of the body (T3, N1, M0).
- Stage IIIB: In this stage, the tumor is spread into chest walls, and it causes swellings in the breast. It may or may not spread from one to nine axillary lymph nodes, but it has not spread to the other parts of the body. In this stage, the tumor is also called inflammatory breast cancer (T4; N0, N1, or N2; M0).
- Stage IIIC: There are two chances in this stage either there is no presence of any cancerous substances in the breast, or the cancer tumor has spread from one to ten axillary lymph nodes. It may also have spread to the chest bone and bone to the collar bone and breast bone. It does not spread to the other body parts (any T, N3, M0).
Stage Ⅳ breast cancer:
Stage Ⅳ of breast cancer is also called metastatic breast cancer. In this stage, the cancer tumor becomes oversized, goes beyond the near lymph nodes, and spreads to the other parts of the body, such as the lungs, liver, brain, and other bones. This stage of breast cancer is diagnosed after the early stage of breast cancer, and it is considered the most advanced stage of breast cancer, also called the de novo metastatic breast cancer (any T, any N, M1).