Metastatic Breast Cancer is breast cancer that spreads to other organs or to lymph nodes far from the
primary tumor in the tissue of the breast, and is also known as Stage IV Breast
What is metastasis, and
how does it happen?
Metastasis means the
spread of cancer. Cancer cells can break away from a primary tumor and enter
the bloodstream or lymphatic system (the system that produces, stores, and
carries the cells that fight infections). That is how cancer cells spread to
other parts of the body. Doctors sometimes refer to metastatic cancer as distant
disease or stage four cancer.
When cancer cells spread
and form a new tumor in a different organ, the new tumor is a metastatic tumor.
The cells in the metastatic tumor come from the original tumor. This means, for
example, that if breast cancer spreads to the lungs, the metastatic tumor in
the lung is made up of cancerous breast cells (not lung cells). In this case,
the disease in the lungs is metastatic breast cancer (not lung cancer). Under a
microscope, metastatic breast cancer cells generally look the same as the
cancer cells in the breast.
How does a doctor know
whether a cancer is a primary or a metastatic tumor?
To determine whether a
tumor is primary or metastatic, a pathologist examines a sample of the tumor
under a microscope. In general, cancer cells look like abnormal versions of
cells in the tissue where the cancer began. Using specialized diagnostic tests,
a pathologist is often able to tell where the cancer cells came from. Markers
or antigens found in or on the cancer cells can indicate the primary site of
Metastatic cancers may
be found before or at the same time as the primary tumor, or months or years
later. When a new tumor is found in a patient who has been treated for cancer
in the past, it is more often a metastasis than another primary tumor.
it possible to have a metastatic tumor without having a primary cancer?
No. A metastatic tumor
always starts from cancer cells in another part of the body. In most cases,
when a metastatic tumor is found first, the primary tumor can be found. The
search for the primary tumor may involve lab tests, x-rays, and other
procedures. However, in a small number of cases, a metastatic tumor is
diagnosed but the primary tumor cannot be found, in spite of extensive tests.
The pathologist knows the tumor is metastatic because the cells are not like
those in the organ or tissue in which the tumor is found. Doctors refer to the
primary tumor as unknown or occult (hidden), and the patient is said to have cancer
of unknown primary origin (CUP). Because diagnostic techniques are constantly
improving, the number of cases of CUP is going down.
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Institute or any other Federal Agency. Advice on the treatment or care of an
individual patient should be obtained through consultation with a physician who
has examined that patient or is familiar with that patient's medical history.
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