When breast cancer is diagnosed, doctors will assign it a stage. It is an important piece of information that can help you understand the extent of the cancer and the treatment options that might be appropriate. It also gives you a way to talk about the cancer. Equip yourself by learning about how stages are determined and what each stage means. If you have questions about your stage of cancer, speak with your doctor.
How is breast cancer staged?
Breast cancer typically falls into one of five stages. The stage is a number on a scale, 0 thru IV. It describes the amount of cancer in the body. Stage 0 means the cancer has not spread beyond the immediate area of origin. For example, if the site of origin is a duct in the breast, the cancer has not spread beyond that duct, and has stayed in its original location. Stage IV means the cancer is invasive and has spread to other parts of the body.
The staging process usually involves a physical exam and biopsy. But surgery or other tests such as X-rays, scans and other imaging procedures, as well as blood work may be required.
The stage is based on four factors:
- The size of the tumor
- If the cancer is invasive beyond its site of origin or non-invasive
- The number of lymph nodes involved (breast cancer tends to spread to the lymph nodes in the underarm area first)
- If the cancer has spread to other parts of the body
Stages of breast cancer
Stage 0 – This describes non-invasive cancer that has not spread to tissues within or beyond the breast. This is the earliest form of breast cancer. It is called carcinoma in situ. With ductal carcinoma in situ (DCIS), the abnormal cells are in the lining of a breast duct, but haven't spread outside it.
Stage I – The cancer is invasive and is spreading into nearby normal tissue. This stage is broken into two categories, IA and IB.
- IA – The breast tumor is no bigger than 2 centimeters (or ¾ of an inch) across. It has not spread to the lymph nodes.
- IB – There is no tumor, but there are small groups of cancer cells — no larger than 2 millimeters — in the lymph nodes.
Or there is a tumor in the breast no larger than 2 centimeters and there are cancer cells in the lymph nodes.
Stage II – The cancer is invasive and the stage is broken into two categories, IIA and IIB.
- IIA – No tumor can be found in the breast, but cancer (larger than 2 millimeters) is found in nearby lymph nodes, under the arm or near the breastbone.
Or the tumor is smaller than 2 centimeters and has spread to nearby lymph nodes.
Or the tumor is between 2 centimeters and 5 centimeters and has not spread to any lymph nodes.
- IIB – The tumor is between 2 centimeters and 5 centimeters. Small groups of breast cancer cells — not larger than 2 millimeters — are in the lymph nodes.
Or the tumor is between 2 centimeters and 5 centimeters. The cancer has spread to nearby lymph nodes.
Or the tumor is larger than 5 centimeters, but has not spread to nearby lymph nodes.
Stage III – The cancer is invasive and the stage is broken into three categories: IIIA, IIIB and IIIC.
- IIIA – No tumor is found in the breast or the tumor may be any size and cancer is in more nearby lymph nodes than in stage II.
Or the tumor is larger than 5 centimeters and small groups of breast cancer cells — not larger than 2 millimeters — are in the lymph nodes.
Or the tumor is larger than 5 centimeters and cancer has spread to nearby lymph nodes.
- IIIB – The tumor may be any size and has spread to the chest wall and/or skin of the breast. It has caused swelling or a sore and may have spread to several nearby lymph nodes.
Or it may have spread to lymph nodes near the breastbone.
- IIIC – There may be no sign of cancer in the breast or there is a tumor of any size that may have spread to the chest wall and/or the skin of the breast and to 10 or more nearby lymph nodes.
Or the cancer has spread to lymph nodes above or below the collarbone.
Or the cancer has spread to nearby lymph nodes in the armpit and near the breastbone.
Stage IV – The cancer is invasive and has spread to other parts of the body far from the breast, such as the bones, lungs, liver or brain.
Your doctor can recommend different treatment options depending on the stage of cancer. However, while staging is an important procedure, there are other tests that can also be done to help determine how the cancer is likely to behave (i.e., whether it is likely to recur or metastasize). Some of these tests might involve testing the genetic material of the cancerous tissue, observing what it looks like under the microscope and determining whether it contains receptors for hormones and other factors. There is no one treatment for everyone, so your plan may vary depending on your situation.
Created on 05/27/1999
Updated on 08/19/2013
- American Cancer Society. How is breast cancer staged?
- Breastcancer.org. Stages of breast cancer.
- National Cancer Institute. What you need to know about breast cancer.