Metastatic Breast Cancer

Cancer that has spread from one part of the body to another part is called metastatic cancer and the secondary tumors that form have cells like the ones in the original (primary) tumor. So if breast cancer has spread to the bones the cancer cells in the bones are actually breast cancer cells. Therefore it is called metastatic breast cancer rather than bone cancer. Doctors refer to this as "distant" or "metastatic disease".

There are several ways that breast cancer cells can escape the original tumor and spread to other organs: Locally (nearby breast tissue), angiolymphatic system (blood and lymph vessels) and lymphatic system (lymph nodes).

The following diagram demonstrates cancer cells that have broken through normal cells:

Local Metastasis:

According to Emory University (Atlanta, Ga) "cancer cells often secrete enzymes that enable it to invade neighboring tissues. These enzymes digest away the barriers to migration and the spread of tumor cells."

As a tumor grows, it puts pressure on surrounding tissues and forces itself through them. Then the cancer will squeeze and block small blood vessels in that area. The lack of blood and oxygen will cause some of the normal tissue to die off, giving it a pathway to invade healthy tissue.

Things like large blood vessels are harder for cancer cells to invade because they have strong walls and dense tissues such as cartilage. So when tumors spread locally, they grow along the path of least resistance.

Angiolymphatic System:

If cancer cells become detached from the primary tumor, they can slip through the wall of a blood vessel and get into the blood stream. Once there, it is carried by the circulating blood until it gets stuck somewhere. Most commonly in very small capillaries. In order to invade other organs, it must break through the wall of the capillary, then multiply to form a new tumor.

Once in the bloodstream, these cells may stick to platelets and form clumps to protect themselves, enabling them to invade the next group of capillaries and tissues and start another tumor. Some cancer cells are likely killed off by white blood cells in the immune system, while others may die from being battered around by the fast flowing blood.

Researchers believe that of the thousands of cancer cells that enter the blood stream, only one will survive to metastasize.

Lymphatic System:

Cancer spreads through the lymphatic system much like the way it spreads through the bloodstream: detaching from the primary tumor, invading the lymph vessels, circulating in lymph fluid until it gets stuck in the small channels inside a lymph node. If this happens, it now has a pathway to other organs via the lymph system.

**A tumor probably uses all three of these ways of spreading, but the one it uses most will depend on the type of tumor. The most common places for breast cancer metastasis are bone, liver, lung and brain.**


Metastases that are too small to be seen are called micrometastases. If there are individual cells, or even small areas of growing cells elsewhere in the body, there is no scan detailed enough to spot them. For some cancers, blood tests can detect proteins released by the cancer cells, which may be a sign that there are metastases that are too small to show up on a scan. But for most cancers there are no blood tests to detect their cells.

Doctors can only "guess" about the potential for micrometastases and if they think it is likely there is, they may offer further treatment options called "adjuvant therapy". They will consider previous experiences of patients with the same type of cancer that was treated the same way. Doctors will collect and publish this information to help each other.

Cancer cells tend to move about more easily than normal cells, and scientists have discovered a substance made by cancer cells which stimulates them to move. This is promising as now researchers can look for ways to inhibit this substances' ability to work and hopefully find ways to stop the cancer cells from making it. Immobolizing cancer cells will certainly aid in the ability to eradicate them.

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Karen Moody ...© All rights reserved