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NCCN Guidelines for Patients



Breast Cancer – Metastatic (STAGE IV), Version 2.2017


Breast cancer basics

Cancer stage



Cancer stage

A cancer stage is a rating by your doctors of the

extent of the cancer. It is used to plan which tests

may be needed and which treatments are best

for you. The AJCC (






ommittee on


ancer) staging system is used to stage breast


Breast cancer is described as stage 0, 1 (I), 2 (II),

3 (III), or 4 (IV). Breast cancers confined within the

nipple, ducts, or lobules are rated stage 0. Breast

cancers that are stage I or II have grown into the

stroma but not into the breast skin or chest wall.

Some stage II cancers have also spread to the

axillary lymph nodes but not elsewhere. Stage III

breast cancers are larger or have spread farther

than stage I or II breast cancers. However, stage III

cancers haven’t spread to distant sites.

Metastatic breast cancer

Metastatic breast cancers have spread to distant

sites outside the breast. Common distant sites

include the bones, lungs, brain, and liver. Breast

cancer in distant sites is still breast cancer. It’s not

lung cancer, for example. Stage IV breast cancer

is metastatic cancer that was present when the

cancer was first found (diagnosis). Sometimes, other

stages of breast cancer spread more and become

metastatic breast cancer.




Inside of women’s breasts are lobules, ducts,

and stroma. Lobules are structures that make

breast milk. Ducts carry breast milk from the

lobules to the nipple. Stroma is a soft tissue

that surrounds the lobules and ducts.



Breast cancer often starts in the milk ducts or

lobules and then spreads into the stroma.



Breast cancer can spread outside the breast

through lymph or blood.



Metastatic breast cancer has spread to distant

sites outside the breast. Stage IV breast

cancer is metastatic cancer that was found at