After a breast cancer diagnosis, doctors will stage the cancer, which helps decide the best treatment options. Staging also helps doctors provide a prognosis and figure out whether clinical trials or experimental treatments might be an option.
There is a staging system for breast cancer that helps doctors accurately stage cancer. This “TNM system” ensures consistency and uniformity in describing cancer so treatment results can be compared from person to person. Information about your tumor can be found in your pathology report after biopsy or surgery.
TNM stands for:
- T is for Tissue – T describes the primary tumor by asking questions like: What is the size of the tumor, and has it grown into nearby tissue?
- TX – The tumor can’t be assessed
- T0 – There isn’t any evidence of a primary tumor
- Tis – The cancer cells are in situ, which means the tumor hasn’t begun invading healthy breast tissue
- T1 to T4 – There is a tumor that has invaded breast tissue; the higher the number, the larger the tumor is and the more it may have grown into surrounding breast tissue
- N is for Nodes – N asks: Has cancer spread into the lymph nodes?
- NX means the lymph nodes can’t be assessed for some reason
- N0 means there is no sign of cancer in the lymph nodes
- N1 to N3 – This is the indicator of how many lymph nodes are involved and the extent of the cancer; the higher the number, the more lymph node involvement there is
- M is for Metastasis – M asks whether cancer spread beyond the breast to distant sites throughout the body.
- MX means metastasis cannot be assessed
- M0 means doctors didn’t detect any distant metastasis
- M1 means the cancer has spread to distant sites in the body
Prior to 2018, doctors staged breast cancer based on those three characteristics alone. But in 2018, the organization that created the TNM guidelines added additional characteristics to help doctors determine stage. While this can complicate breast cancer staging, it also makes it more accurate. The characteristics added include:
- Tumor grade, which measures the portion of cancer cells that look like normal breast tissue cells
- Estrogen- and progesterone-receptor status, which provides information about whether the cancerous cells have hormone receptor cells for estrogen and progesterone
- HER2 status, which lets doctors know whether the cells are making too much of the HER2 protein
- Oncotype DX score, which can be given if cancer is estrogen-receptor positive and HER2 negative and cancer has not spread to the lymph nodes
Stages of breast cancer
Once the tumor has been evaluated for different characteristics, doctors will assign it a stage. There are five stages ranging from 0 to IV, and stages I through IV have subcategories, such as IA and IVC.
Stage 0
Stage 0 is the stage given to non-invasive cancers, like ductal carcinoma in situ (DCIS). Stage 0 means doctors did not find evidence of cancer cells moving beyond the original site or invading nearby tissue.
Stage I
Stage I is invasive breast cancer, which means cancer cells have invaded normal breast tissue. There are two categories of Stage I – IA and IB.
Generally speaking, in stage IA, the tumor is smaller than two centimeters and hasn’t spread to the lymph nodes or elsewhere outside the breast tissue. IB cancers either have no tumor in the breast, but there is no abnormal cell growth in the lymph nodes or there is a breast tumor smaller than two centimeters and there are small growths in the lymph nodes.
Stage II
Stage II is also invasive breast cancer. It is broken down into two subcategories – IIA and IIB. Whether cancer is considered IA or IB depends on several factors, including tumor size and lymph node involvement.
Stage III
Stage III is also invasive. It is divided into subcategories known as IIIA, IIIB, and IIIC. Like stage II, the stage is determined based on factors such as tumor size, tumor location, and lymph node involvement. In stage IIIB, the cancer may also have spread to the chest wall or breast skin.
One type of breast cancer, called inflammatory breast cancer, is always at least stage IIIB.
Stage IV
Stage IV breast cancer is invasive cancer that has spread beyond the breast to distant sites in the body. Common areas for breast cancer metastasis are the lungs, skin, brain, liver, bones and distant lymph nodes. Stage IV breast cancer may be classified as a first diagnosis, which is called de novo, or it can be a recurrence of previous breast cancer that is now found in other parts of the body. (Even if it is found in another part of the body, such as the liver, it is still considered breast cancer.)
Early detection saves lives: Mammograms at Beaumont
Having regular mammograms is an important part of detecting breast cancer early. The earlier cancer is found, the better the outcomes are. To schedule a mammogram at Beaumont, call 800-328-8542 today.
Beaumont’s Comprehensive Breast Care Program
The Comprehensive Breast Care Program at Beaumont Hospitals integrates cancer prevention, early detection, rapid diagnosis, leading-edge therapies, and several support, education, and community-support programs. For an expedited and comprehensive breast evaluation, call 888-924-9460.