Stage IIA

• If the tumor is 0 to 2 cm in size, it has only spread to one to three axillary lymph nodes, which are located in the armpit, and tiny amounts of cancer may be found on internal mammary lymph nodes, which are inside the chest, located near the breastbone. If the tumor is greater than 2 cm in size, it has not spread to any axillary lymph nodes.
  
  

Stage IIB

• In this stage, the tumor may be larger, between 2 and 5 cm in size. If so, it has only spread to one to three axillary lymph nodes, and tiny amounts of cancer may be found on internal mammary lymph nodes. If the tumor is greater than 5 cm in size, it has not spread to any axillary lymph nodes and does not grow into the chest wall or skin.
  
  

Stage IIIA

• In this stage, the tumor may be in excess of 5 cm in size, but if so, it does not grow into the chest wall or skin and has spread from one to nine axillary lymph nodes or to the internal mammary lymph nodes. If the tumor is 0 to 5 cm in size, it has spread to five to nine axillary lymph nodes or has enlarged internal mammary lymph nodes.
  
  

Stage IIIB

• This stage marks the beginning of stages in which the cancer has grown into the chest wall or skin. The tumor has either spread to one to three axillary lymph nodes and/or spread in tiny amounts to the internal mammary lymph nodes, or it has spread to four to nine axillary lymph nodes or enlarged the internal mammary lymph nodes.
  
  

Stage IIIC

• The tumor is any size and has spread to 10 or more axillary lymph nodes, has spread to the lymph nodes under or above the clavicle, and/or involves both the axillary and internal mammary lymph nodes. This is the final stage used to describe breast cancer that has not spread to other major organs.