Breast Cancer Staging

When cancer is diagnosed, your physician and pathologist will begin the process of staging, which is determining how widespread the cancer is in the body. Cancer stages are normally expressed numerically from 0 to IV, with 0 being a non-invasive cancer and IV being an advanced cancer that has spread to other body parts.

How is breast cancer staged?

By using the results of imaging tests, biopsies, and surgery, pathologists will be able to determine the extent breast cancer has spread throughout the body.*

Stage 0

Stage 0 breast cancer is ductal carcinoma in situ (DCIS) or pre-cancer of the breast. DCIS means that the cancer cells have formed in the milk ducts but have not spread to other breast tissue.

Stage IA

In stage IA breast cancer, the tumor is two centimeters or less in diameter and has not begun to spread into lymph nodes or other body parts.

Stage IB

In stage IB breast cancer, the tumor is also two centimeters or less in diameter, but it has begun to spread into lymph nodes.

Stage IIA and IIB

Stage IIA and IIB breast cancer indicates that the tumor is two centimeters or less in diameter and has spread into one to three axillary lymph nodes, internal mammary lymph nodes, or underarm lymph nodes.

Stage IIIA

In stage IIIA breast cancer, the tumor has grown to no more than five centimeters in diameter, has spread into four to nine axillary lymph nodes, or has enlarged internal mammary lymph nodes but has not spread into other body parts.

Stage IIIB

In addition to the factors of stage IIIA breast cancer, in stage IIIB, breast cancer has spread into the chest wall or skin. Inflammatory breast cancer is classified as at least stage IIIB or stage IIIC if it has spread into lymph nodes.

Stage IIIC

In stage IIIC breast cancer, the tumor can be any size but has spread to at least 10 axillary lymph nodes, or lymph nodes under the clavicle bone, or lymph nodes above the clavicle, or the cancer has enlarged internal mammary lymph nodes.

Stage IV

In stage IV breast cancer, the cancer may be any size and may have spread to lymph nodes, but it has spread to other body parts. Breast cancer commonly spreads to bones, liver, brain, or lungs if it is infiltrating other body parts.

*These stages are to be determined by your physician and pathologist following the standardized stages of the American Joint Committee on Cancer (AJCC) system.