NCCN Guidelines for Patients
Breast Cancer – Metastatic (STAGE IV), Version 2.2017
Breast cancer basics
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 (
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