Breast Cancer Diagnosis & Staging
Lumps in the breast, or changes in breast shape, size, or skin
qualities can be caused by many different conditions.
A positive breast cancer diagnosis can only be achieved through an
examination of breast tissue. Biopsies play a critical role in breast cancer
diagnoses. To understand diagnoses, you should understand the stages of breast
cancer and what each means for overall outlook. Make note of all your symptoms
and communicate clearly with your doctor about how your body is feeling.
Breast Cancer Staging
Breast cancer must be staged before a diagnosis can be complete
and a treatment course chosen. The process determines whether cancer has spread
from the breast to other parts of the body. The most commonly used system is
the American Joint Committee on Cancer TNM system. In the TNM staging system,
cancers are classified based on their T, N, and M stages:
- T indicates the size of the tumor and how
far it has spread within the breast and to nearby organs.
- N stands for how much it has spread to
- M defines metastasis, or how much it has
spread to distant organs.
In TNM staging, each letter is associated with a number to explain
how far the cancer has progressed. Once the TNM staging has been determined,
this information is combined into a process called “stage grouping.” Stage
grouping is the common staging method, in which stages range from 0 to 4. The
lower the number, the earlier the cancer stage.
This stage describes noninvasive (“in situ”) breast cancer. Ductal
carcinoma in situ (DCIS) is an example of stage 0 cancer.
These breast cancers are subdivided into two categories (1A and 1B)
based on a number of criteria.
This stage marks the first identification of invasive breast
cancer. At this point, the tumor measures no more than 2 centimeters in
diameter (or about 3/4 inch). Stage 1 breast cancer is divided into stages 1A
Stage 1A means that the tumor is 2
centimeters or smaller, and that the cancer hasn’t spread anywhere outside the
Stage 1B means that small clusters
of breast cancer cells are found in the lymph nodes. Typically at this stage, either
no discrete tumor is found in the breast or the tumor is 2 centimeters or
This stage describes invasive breast cancers in which one of the
following is true:
- The tumor
measures less than 2 centimeters (3/4 inch), but has spread to lymph nodes
under the arm.
- The tumor
is between 2 and 5 centimeters (about 3/4 inch to 2 inches) and may or may not
have spread to lymph nodes under the arm.
- The tumor
is larger than 5 centimeters (2 inches), but hasn't spread to any lymph nodes.
- No discrete
tumor is found in the breast, but breast cancer larger than 2 millimeters is found
in 1-3 lymph nodes under the arm or near the breastbone.
Stage 2 breast cancer is divided into stage 2A and 2B.
In stage 2A, no tumor
is found in the breast or the tumor is smaller than 2 centimeters. Cancer may
be found in the lymph nodes at this point. Or the tumor is larger than 2
centimeters but smaller than 5 centimeters and the cancer has not spread to the
In stage 2B, the tumor
may be larger than 2 centimeters, smaller than 5 centimeters, and breast cancer
cells are found in the lymph nodes. Or the tumor may also be larger than 5
centimeters, but cancer hasn’t spread to the lymph nodes.
By definition, stage 3 cancers have not spread to distant sites.
- Stage 3A tumors are
either larger than 5 centimeters (2 inches) and have spread to one to
three lymph nodes under the arm, or are any size and have spread into
multiple lymph nodes.
- A stage 3B tumor
of any size has spread to tissues near the breast — the skin and chest
muscles — and may have spread to lymph nodes within the breast or under
- Stage 3C cancer is
a tumor of any size that has spread:
- to 10 or more
lymph nodes under the arm
- to lymph nodes
above or beneath the collarbone and near the neck on the same side of the
body as the affected breast
- to lymph nodes
within the breast itself and under the arm
Stage 4 breast cancer has spread to distant parts of the body, such
as the lungs, liver, bones, or brain. At this stage, cancer is advanced and
curative treatment options are very limited.