From breastcancer.org
Stages of Breast Cancer. Cancer stage is based on the size of the tumor, whether the cancer is invasive or non-invasive, whether lymph nodes are involved, and whether the cancer has spread beyond the breast.
The purpose of the staging system is to help organize the different factors and some of the personality features of the cancer into categories, in order to:
- best understand your prognosis (the most likely outcome of the disease)
- guide treatment decisions (together with other parts of your pathology report), since clinical studies of breast cancer treatments that you and your doctor will consider are partly organized by the staging system
- provide a common way to describe the extent of breast cancer for doctors and nurses all over the world, so that results of your treatment can be compared and understood
Stage 0
Stage 0 is used to describe non-invasive breast cancers, such as DCIS and LCIS. In stage 0, 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 of getting through to or invading neighboring normal tissue.
Stage I
Stage I describes invasive breast cancer (cancer cells are breaking through to or invading neighboring normal tissue) in which:
- the tumor measures up to 2 centimeters, AND
- no lymph nodes are involved
Stage II
Stage II is divided into subcategories known as IIA and IIB.
Stage IIA describes invasive breast cancer in which:
- no tumor can be found in the breast, but cancer cells are found in the axillary lymph nodes (the lymph nodes under the arm), OR
- the tumor measures 2 centimeters or less and has spread to the axillary lymph nodes, OR
- the tumor is larger than 2 centimeters but not larger than 5 centimeters and has not spread to the axillary lymph nodes
Stage IIB describes invasive breast cancer in which:
- the tumor is larger than 2 but no larger than 5 centimeters and has spread to the axillary lymph nodes, OR
- the tumor is larger than 5 centimeters but has not spread to the axillary lymph nodes
Stage III
Stage III is divided into subcategories known as IIIA, IIIB, and IIIC.
Stage IIIA describes invasive breast cancer in which either:
- no tumor is found in the breast. Cancer is found in axillary lymph nodes that are clumped together or sticking to other structures, or cancer may have spread to lymph nodes near the breastbone, OR
- the tumor is 5 centimeters or smaller and has spread to axillary lymph nodes that are clumped together or sticking to other structures, OR
- the tumor is larger than 5 centimeters and has spread to axillary lymph nodes that are clumped together or sticking to other structures
Stage IIIB describes invasive breast cancer in which:
- the tumor may be any size and has spread to the chest wall and/or skin of the breast AND
- may have spread to axillary lymph nodes that are clumped together or sticking to other structures, or cancer may have spread to lymph nodes near the breastbone
- Inflammatory breast cancer is considered at least stage IIIB.
Stage IIIC describes invasive breast cancer in which:
- 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 lymph nodes above or below the collarbone, AND
- the cancer may have spread to axillary lymph nodes or to lymph nodes near the breastbone
Stage IV
Stage IV describes invasive breast cancer in which:
- the cancer has spread to other organs of the body -- usually the lungs, liver, bone, or brain
"Metastatic at presentation" means that the breast cancer has spread beyond the breast and nearby lymph nodes, even though this is the first diagnosis of breast cancer. The reason for this is that the primary breast cancer was not found when it was only inside the breast. Metastatic cancer is considered stage IV.
Additional staging information
You may also hear terms such as "early" or "earlier" stage, "later," or "advanced" stage breast cancer. Although these terms are not medically precise (they may be used differently by different doctors), here is a general idea of how they apply to the official staging system:
Early stage
- Stage 0
- Stage I
- Stage II
- Some stage III
Later or advanced stage
- Other stage III
- Stage IV
Doctors use a staging system to determine how far a cancer has spread. The most common system is the TNM staging system. You may hear the cancer described by three characteristics:
- size (T stands for tumor)
- lymph node involvement (N stands for node)
- whether it has metastasized (M stands for metastasis)
The T (size) category describes the original (primary) tumor:
- TX means the tumor can't be measured or found.
- T0 means there isn't any evidence of the primary tumor.
- Tis means the cancer is "in situ" (the tumor has not started growing into the breast tissue).
- The numbers T1-T4 describe the size and/or how much the cancer has grown into the breast tissue. The higher the T number, the larger the tumor and/or the more it may have grown into the breast tissue.
The N (node involvement) category describes whether or not the cancer has reached nearby lymph nodes:
- NX means the nearby lymph nodes can't be measured or found.
- N0 means nearby lymph nodes do not contain cancer.
- The numbers N1-N3 describe the size, location, and/or the number of lymph nodes involved. The higher the N number, the more the lymph nodes are involved.
The M (metastasis) category tells whether there are distant metastases (whether the cancer has spread to other parts of body):
- MX means metastasis can't be measured or found.
- M0 means there are no distant metastases.
- M1 means that distant metastases were found.
Once the pathologist knows your T, N, and M characteristics, they are combined in a process called stage grouping, and an overall stage is assigned.
For example, a T1, N0, M0 breast cancer would mean that the primary breast tumor:
- is less than 2 centimeters across (T1)
- does not have lymph node involvement (N0)
- has not spread to distant parts of the body (M0)
This cancer would be grouped as a stage I cancer.
