Breast cancer may be divided into several stages, reflecting the size of the tumor and the extent to which the cancer has spread in the body. Generally, the lower the number of the stage, the less the cancer has spread. Determining the stage of a cancer can aid in treatment decisions and establishing a prognosis, i.e., predicting the course of the disease and the chances of remission and/or recurrence. For more detail, see the section on Biopsies and examination of tissues in the Anatomic Pathology feature article.
|Stage||Size of the tumor||Location|
|Stage 0||Confined within the breast ducts (ductal carcinoma in situ, DCIS) or confined within the lobules (lobular carcinoma in situ, LCIS)|
|Stage I||Less than 2 cm (3/4 inch) across||Tumor has spread beyond the ducts but is still confined within the breast tissue|
|Stage IIA||Less than 2 cm across or no tumor||Spread to one to three lymph nodes in the armpit (axilla)|
|Between 2 and 5 cm (3/4 to 2 inches) across||No spread to the lymph nodes|
|Stage IIB||2 to 5 cm across||Spread to the lymph nodes|
|Larger than 5 cm across||No spread to the lymph nodes|
|Stage IIIA||Spread to lymph nodes in the armpit that are attached to each other or other structures and may have spread to lymph nodes behind the breast bone|
|Stage IIIB||Any size||
Spread to chest wall or skin of the breast; may have spread to lymph nodes in the armpit and may have spread to behind the breast bone
Inflammatory breast cancer, a rare type of cancer that does not form a lump, usually falls into this category because it is aggressive.
|Stage IIIC||Any size||Spread to lymph nodes in the armpit and to lymph nodes either behind the breast bone or above the collar bone|
|Stage IV||Any size||Spread to distant organs such as bone or liver|
|Recurrent||Any size||Breast cancer that was undetected after treatment but is now detectable in any area of the body|