Stages of Breast Cancer

Stage 0	100%
Stage I	98%
Stage II	88%
Stage IIIA	56%
Stage IIIB	49%
Stage IV	16%

Stage 0—Carcinoma in situ

In stage zero breast cancer, atypical cells have not spread outside of the ducts or lobules, the milk producing organs, into the surrounding breast tissue. Referred to as carcinoma in situ, it is classified in two types:

• Ductal Carcinoma In Situ (DCIS)— very early cancer that is highly treatable and survivable. If left untreated or undetected, it can spread into the surrounding breast tissue. 

• Lobular Carcinoma In Situ (LCIS)—not a cancer but an indicator that identifies a woman as having an increased risk of developing breast cancer.

Stage I—Early stage invasive breast cancer

In stage 1 breast cancer, the cancer is no larger than two centimeters (approximately an inch) and has not spread to surrounding lymph nodes or outside the breast.

Stage II

Stage 2 breast cancer is divided into two categories according to the size of the tumor and whether or not it has spread to the lymph nodes:

• Stage II A Breast Cancer—the tumor is less than two centimeters(approximately an inch) and has spread up to three auxiliary underarm lymph nodes. Or, the tumor has grown bigger than two centimeters, but no larger than five centimeters (approximately two inches) and has not spread to surrounding lymph nodes.
• Stage II B Breast Cancer— the tumor has grown to between two and five centimeters (approximately one to two inches) and has spread to up to three auxiliary underarm lymph nodes. Or, the tumor is larger than five centimeters, but has not spread to the surrounding lymph nodes.

Stage III

Stage 3 breast cancer is also divided in to two categories:

• Stage III A Breast Cancer—the tumor is larger than two centimeters but smaller than five centimeters (approximately one to two inches) and has spread to up to nine auxiliary underarm lymph nodes.
• Stage III B Breast Cancer— the cancer has spread to tissues near the breast including the skin, chest wall, ribs, muscles, or lymph nodes in the chest wall or above the collarbone.

Stage IV

In stage 4 breast cancer, the cancer has spread to other organs or tissues, such as the liver, lungs, brain, skeletal system, or lymph nodes near the collarbone.