Why Breast Cancer Staging?

Each cancer is unique, each woman is different, and the combination of treatment options is practically endless. To help determine who should get what treatment, cancer specialists rely on breast cancer staging—a system that places the breast cancer into a certain group. The stage of your tumor is the most important factor in deciding what type of treatment is best for you.


In simplified form, breast cancer staging is based on: the size of the tumor; presence of cancer cells in the lymph nodes; and metastasis, or spread, to other organs. This is the so-called TNM—tumor, node, metastasis—staging system.

Tumor size is determined when the tumor is removed and sent to the pathologist.

Lymph nodes are checked for evidence of tumor spread at the time of surgery in a procedure called axillary lymph node dissection.

Metastasis, or spread to other organs, is assessed with bone scans, X-rays, CT scans, and blood tests. Putting all this information together is called staging.

Stages of Breast Cancer

Tumor size is part of breast cancer staging

Breast cancer staging includes five stages

Stage 0 (in situ)
Non-invasive breast cancer (DCIS, LCIS). No cancer cells have penetrated the lining of the duct or lobule.

Stage I
Invasive tumor, 2 cm (3/4 inch) or smaller. Axillary lymph nodes are negative and there is no evidence of distant metastases.

Stage II
Tumor is 2-5 cm in size (about 3/4 to 2 inches). Axillary lymph nodes may or may not be positive for cancer. Even if the tumor is smaller than 2 cm, but the lymph nodes are positive, cancer is also considered Stage II.

Stage III
Tumor is larger than 5 cm (2 inches) with extensive lymph node spread. Tumor may extend into the pectoral muscles or into the skin of the breast, but there are no distant metastases.

Stage IV
If the tumor has spread to other organs, usually lungs, liver, bone and brain, it is Stage IV regardless of its size, or of the number of positive axillary lymph nodes.


Treatment Options

You may find it helpful to think of breast cancer staging as degree of risk presented by a particular tumor.

At one end of the scale are the low-risk situations: very tiny tumors that have not spread to lymph nodes, and that are composed of cells that are not very aggressive.

Further along are slightly larger tumors, still smaller than about a half inch (1 cm), still without evidence of lymph node spread, but often more aggressive.

At the other end of the breast cancer staging scale are the situations that involve the greatest risk: larger tumors that have invaded the lymph nodes.

If you are at the low-risk end of the scale, your treatment may require breast conserving surgical removal of the tumor plus a course of radiation therapy, and perhaps a less aggressive form of hormonal therapy or chemotherapy.

Larger tumors may be treated with more aggressive chemotherapy.

For high-risk tumors, at the far end of the scale, there are a wide variety of options, including dose dense chemotherapy.