IIIA means the cancer has been found in up to nine of the lymph nodes that form a chain from your underarm to your collarbone. Or it has spread to or enlarged the lymph nodes deep in your breast. In some cases there is a large tumor in the breast, but other times there’s no tumor.
IIIB means the tumor has grown into the chest wall or skin around your breast, even if it hasn’t spread to the lymph nodes.
IIIC means cancer has been found in 10 or more lymph nodes, or has spread above or below your collarbone. It’s also IIIC if fewer lymph nodes outside the breast are affected but those inside it are enlarged or cancerous.
Stage IV. Breast cancer stage 4 cells have spread far away from the breast and lymph nodes right around it. The most common sites are the bones, lungs, liver, and brain. This stage is described as “metastatic,” meaning it has spread beyond the region of the body where it was first found.