Stages of breast cancer

Stages of breast cancer
Your stage of breast cancer refers to how extensive the cancer is, on a scale from stage 0 to stage IV.

Your doctor determines your stage of breast cancer through examination of the tissue removed during a mastectomy or lumpectomy and of the lymph nodes under your arm (axillary lymph nodes).

Staging your cancer gives your doctor an idea of your prognosis — the likely outcome of your disease — and helps guide treatment decisions. The 0 to 4 staging system, based on data from large numbers of people with breast cancer, estimates your chance of surviving for at least five years after your diagnosis. The numbers express probability, not certainty. With advances in detection and treatment, people with breast cancer are living longer than ever before.

Tumor size
Your breast cancer stage depends partly on the size of your tumor and partly on whether cancer cells have spread from the breast to other areas of your body, including your lymph nodes. The higher the stage, the larger the tumor or the more the cancer has spread. In stages I and II, tumors are generally no more than 2 centimeters (cm), or about 3/4 inches, in diameter — about the size of a corn kernel or a shelled peanut. Stage III and stage IV tumors tend to be more than 5 cm (2 in) in diameter — about the size of a small lime — but smaller tumors may have spread beyond the breast by the time they're detected.

Stage I breast cancer
You have stage I breast cancer if:

Your tumor is no more than 2 cm (3/4 in) in diameter
The cancer hasn't spread to your lymph nodes
The cancer hasn't spread outside your breast
The five-year overall survival rate for women treated for stage I breast cancer is close to 100 percent. This refers to the number of people who live at least five years after their cancer is found.
Stage II breast cancer
A stage II breast tumor is larger than a stage I tumor, but the cancer hasn't spread to a distant part of your body. If your cancer is stage II, one of the following is true:

Your tumor is 2 to 5 cm (3/4 to 2 in) in diameter. The cancer may or may not have spread to your underarm (axillary) lymph nodes.
Your tumor is more than 5 cm (2 inches) in diameter, but the cancer hasn't spread to your axillary lymph nodes (A).
Your tumor is less than 2 cm (3/4 in) in diameter, but the cancer has spread to no more than three of your axillary lymph nodes (B).
No tumor is found in the breast, but the cancer has spread to no more than than three of your axillary lymph nodes.
The five-year overall survival rate for women treated for stage II breast cancer is 86 percent to 91 percent.

Stage III breast cancer
If you have stage III breast cancer, known as locally or regionally advanced cancer, your cancer may have spread to lymph nodes near your breast — those located under your arm or by your collarbone — but not to more distant parts of your body. Here are some examples:

You may have a tumor that's larger than 5 cm (2 in), with cancer cells that have spread to your axillary lymph nodes. However, the nodes aren't attached to one another (A).
Your tumor is smaller than 5 cm (2 in), but the cancer has spread into nearby lymph nodes and the nodes are growing into each other or the surrounding tissue (stroma).
Your tumor is smaller than 5 cm (2 in), but the cancer has spread to the axillary lymph nodes above your collarbone (B).

Inflammatory breast cancer
Inflammatory breast cancer — in which the cancer has spread to lymphatic vessels in breast skin, causing swelling, redness, and ridged or dimpled skin — is classified as stage III breast cancer.

The five-year overall survival rate for women treated for stage III breast cancer is 54 percent to 67 percent.

Stage IV breast cancer
Stage IV is the most advanced form of breast cancer. Cancer cells have spread to distant parts of your body, such as bones, organs or lymph nodes far from your breast. Treatment may help shrink or control the cancer for a while, but it usually won't completely cure the cancer. At this stage, symptom relief becomes a priority. The five-year overall survival rate for stage IV breast cancer is 20 percent