What is metastatic breast cancer?

MBC is breast cancer that has left the breast and local area around the breast and has been found in other parts of the body. Although MBC is not curable, with current advances in treatment, it is now often considered a chronic disease – one that may be treated on an ongoing basis and lived with for years.


MBC is also called “stage IV” breast cancer or “mets.” MBC is also often referred to as “advanced breast cancer,” although they are not the same. MBC is advanced breast cancer, but advanced breast cancer can also refer to some stage III cancers that are not MBC.

Common Locations

Breast cancer is more likely to spread to the bones, liver, lungs, or brain than other parts of the body, though it can be found elsewhere. Breast cancer that is found in one of these parts of the body outside the breast is still made up of breast cancer cells and still called breast cancer. Metastasis to the bones is not bone cancer, for example; it is breast cancer that has moved from the breast to the bone. Breast cancer metastases, no matter where they are now located, will respond best to breast cancer treatments.

How many women get MBC?

Approximately 5 to 9% of women who are diagnosed with breast cancer for the first time are diagnosed with MBC at time of initial diagnosis. Approximately 20-30% of women with early stage breast cancer will later develop metastases.

How is MBC diagnosed?

MBC diagnoses are often found by a symptom – perhaps a recurring pain or cough, shortness of breath, lack of appetite, headaches or an injury. It is also possible to learn of metastases through routine scans [hyperlink to mets tests page], although studies show that finding metastases early does not create better outcomes or lengthen survival. It is important to avoid blaming yourself for not finding your recurrence early if you missed a scan or test or put off getting something checked out for a little while. An absolute diagnosis of MBC cannot be made with a biopsy.

Is MBC curable?

Generally, no. Once metastases have been found, treatment becomes focused on managing the cancer for as long as possible and relieving discomfort, with the hope that the disease will disappear, at least for a period of time. This is called “no evidence of disease” or NED. The goal is to increase length of survival and maintain a good quality of life.  A small percentage of women with MBC (1 to 3 %) may remain NED indefinitely after treatment.

Metastatic Disease