After a biopsy or surgery to remove the breast cancer, a pathologist examines the tissue and may run additional tests to create a pathology report to help create an appropriate treatment plan for the patient. In addition, the use of an Oncotype Dx® Recurrence Score results may also be considered and used to determine certain treatment.

Stage 0, carcinoma in situ, is the earliest stage of breast cancer, followed by:

• Stage 1: The tumor is 2 centimeters or smaller; the cancer has not spread outside of the organ; or small clusters of cancer cells are found in the lymph nodes.

• Stage 2: There is no tumor, or the tumor is smaller than 2 centimeters, but the cancer is also found in the lymph nodes or the breast; or the tumor is larger than 2 to 5 centimeters, but the cancer has not spread to lymph nodes.

• Stage 3: There is no tumor, or the tumor can be any size, but the cancer has spread to the lymph nodes; the tumor is larger than 5 centimeters and small clusters of cancer cells are found in the lymph nodes or the breast; or the tumor is larger than 5 centimeters and the cancer has spread to the lymph nodes.

• Stage 4: The cancer has spread to other parts of the body, often in the bones, lungs, brain or liver.

When determining the stage of breast cancer, key pieces of information include the size of the tumor, its spread to nearby lymph nodes, metastasis to other parts of the body, grade of the cancer, as well as estrogen receptor, progesterone receptor and HER2 status.