The language and protocols for determining the various stages of breast cancer can be daunting to understand.
The breast cancer staging system, called the TNM system, is overseen by the American Joint Committee on Cancer (AJCC). The AJCC is a group of cancer experts who oversee how cancer is classified and communicated.
TNM stands for the following:
- T represents the size of the cancer tumor and whether it has grown into nearby tissue;
- N represents whether the cancer is in the lymph nodes;
- M represents whether the cancer has spread to other parts of the body beyond the breast.
A pathology report will begin to reveal the state of the cancer; but a more thorough understanding will happen once the doctor has performed the initial surgery to remove the cancer.
You may see written or hear from the doctor the following terms that begin to describe the stage of the cancer:
- Local: The cancer is confined within the breast.
- Regional: The lymph nodes, primarily those in the armpit, are involved.
- Distant: The cancer is found in other parts of the body as well.
Following is a brief description of the five stages of breast cancer. These descriptions are topline only and focus more on the size and location of the tumor or cancer cells. For a more in-depth review of the five stages, please see: https://www.breastcancer.org/symptoms/diagnosis/staging
Stage 0 describes non-invasive breast cancers. There is no evidence of cancer cells or non-cancerous abnormal cells breaking out of the part of the breast in which they started or getting through to or invading neighboring normal tissue.
Stage I describes invasive breast cancer (cancer cells are breaking through to or invading normal surrounding breast tissue). Stage I is divided into subcategories called IA and IB.
- Stage IA
- The tumor measures up to 2 centimeters (CM) and
- The cancer has not spread outside the breast; no lymph nodes are involved
- Stage IB
- There is no tumor in the breast; instead, small groups of cancer cells — larger than 0.2 millimeter (mm) but not larger than 2 mm — are found in the lymph nodes or
- There is a tumor in the breast that is no larger than 2 cm, and there are small groups of cancer cells — larger than 0.2 mm but not larger than 2 mm — in the lymph nodes
Stage II describes invasive breast cancer and is divided into subcategories IIA and IIB.
- Stage IIA
- No tumor can be found in the breast, but cancer (larger than 2 millimeters [mm]) is found in 1 to 3 axillary lymph nodes (the lymph nodes under the arm) or in the lymph nodes near the breast bone (found during a sentinel node biopsy) or
- The tumor measures 2 centimeters (cm) or smaller and has spread to the axillary lymph nodes or
- The tumor is larger than 2 cm but not larger than 5 cm and has not spread to the axillary lymph nodes
- Stage IIB
- The tumor is larger than 2 cm but no larger than 5 centimeters; small groups of breast cancer cells — larger than 0.2 mm but not larger than 2 mm — are found in the lymph nodes or
- The tumor is larger than 2 cm but no larger than 5 cm; cancer has spread to 1 to 3 axillary lymph nodes or to lymph nodes near the breastbone (found during a sentinel node biopsy) or
- The tumor is larger than 5 cm but has not spread to the axillary lymph nodes
Stage III describes invasive breast cancer and is divided into subcategories IIIA, IIIB, IIIC.
- Stage IIIA
- No tumor is found in the breast or the tumor may be any size; cancer is found in 4 to 9 axillary lymph nodes or in the lymph nodes near the breastbone (found during imaging tests or a physical exam) or
- The tumor is larger than 5 centimeters (cm); small groups of breast cancer cells (larger than 0.2 millimeter [mm] but not larger than 2 mm) are found in the lymph nodes or
- The tumor is larger than 5 cm; cancer has spread to 1 to 3 axillary lymph nodes or to the lymph nodes near the breastbone (found during a sentinel lymph node biopsy)
- Stage IIIB
- The tumor may be any size and has spread to the chest wall and/or skin of the breast and caused swelling or an ulcer and
- May have spread to up to 9 axillary lymph nodes or
- May have spread to lymph nodes near the breastbone
- Stage IIIC
- There may be no sign of cancer in the breast or, if there is a tumor, it may be any size and may have spread to the chest wall and/or the skin of the breast and the cancer has spread to 10 or more axillary lymph nodes or
- The cancer has spread to axillary lymph nodes or to lymph nodes near the breastbone
- The cancer has spread to lymph nodes above or below the collarbone or
Stage IV describes invasive breast cancer that has spread beyond the breast and nearby lymph nodes to other organs of the body, such as the lungs, distant lymph nodes, skin, bones, liver, or brain.
Breast cancer staging is a complex system designed to take into consideration the myriad of factors necessary for proper identification to be able to propose the best treatment options. TO learn more, visit these sources, used for the content of this article:
The sources referenced in this article are good resources to aid in understanding this complex issue.