Breast Cancer: Staging

Once the tumor has been identified, breast cancer will be classified according to its stage of growth. This will help determine the best possible treatment.

Stage 0 (early stage): Includes findings of DCIS or Paget’s disease, but no actual tumor.
Stage I (early stage): Tumor no more than 2 cm across, with no spread to lymph nodes.
Stage II (early stage): Tumor 2 to 5 cm across, and cancer has spread to underarm lymph nodes.
Stage IIA: Tumor less than 2 cm with lymph node involvement, or cancer between 2 and 5 cm with no lymph node involvement.
Stage IIB: Tumor larger than 2 cm with lymph node involvement.
Stage III: Also called locally advanced cancer, tumor larger than 5 cm, with extensive cancer in underarm lymph nodes, or that has spread to other lymph node areas or tissues near the breast (such as above or below the clavicle).
Stage IIIA: Tumor larger than 5 cm with involvement of underarm lymph nodes. Any tumors fitting the description above.
Stage IIIB: As in IIIA, and associated with chest wall or skin involvement, or with spread to lymph node above the clavicle.
Stage IV: Cancer has spread to another organ in the body (also called metastatic cancer).