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When Melanoma Metastasizes: What Does It Mean?
   

When patients are diagnosed with Clark's level III or higher, there is a good chance that the melanoma cells may have spread, or metastasized, from the original site into the lymph and blood systems, even if they cannot be detected at the time of diagnosis.

Metastases are often classified as regional or systemic. Regional metastases are located in the first lymph node area draining the primary site and anywhere between the primary site and those lymph nodes. For example, one patient had a primary melanoma removed from the skin on his right calf. Four years later he was found to have nodules under the skin of his right upper leg and enlarged lymph nodes in his right groin that were proved by fine needle aspiration (FNA) to contain melanoma cells. Doctors were unable to detect metastases anywhere else in his body, and his metastases were classified as regional. If this patient is later found to have melanoma cells in his liver and lung, these new sites would be classified as systemic metastases. The terms that are used to describe these two conditions are regionally advanced disease and advanced systemic disease. Their treatment may be very different.

More Information About Metastases

Malignant melanoma is unique among cancers in that it will metastasize to almost any organ in the body; we do not know why. When most cancers spread, they like to grow in particular organs. For example, breast cancer cells usually spread to the bones, and colon cancer cells usually spread to the liver. Once melanoma cells are in the bloodstream, they pass through all the organs. To form a metastasis in an organ, melanoma cells must first adhere to a blood vessel in that organ. Then they must penetrate the wall of the blood vessel and set up a kind of nest in the tissue of the organ. Finally, they release cytokines that bring new blood vessels to them for nourishment. Once they have developed a blood supply of their own, they are off and growing.

Each organ has its own chemical environment. Most melanoma cells will find the environment of a particular organ hostile. They may be killed or they may simply not be able to perform one or more of the operations needed for tumor formation. As the melanoma cells mutate, however, one or more of them may become adapted to the environment of a particular organ and can begin to grow there.

Although melanoma cells may metastasize to any part of the body, metastases in the vast majority of melanoma patients do follow a pattern. They are most likely to show up first as subcutaneous (under the skin) nodules, or in the lymph nodes, and then in the lungs, liver, and brain. It is not unusual, however, to find that melanoma has metastasized to the spleen, adrenal glands, intestines, bones, or bone marrow. It is uncommon for melanoma to invade the heart, the muscles, or any of the remaining organs, but it is not unheard of. Patients who die of the disease are most likely to die of brain metastases, but by this time, they usually have tumors in many other parts of their bodies as well.

Scientists are working hard to figure out the mechanisms of melanoma metastases. Such understanding will be key to the development of new and better treatments. The type of treatment currently used for metastatic melanoma depends on which organs are involved. Treatment may include chemotherapy, immunotherapy, surgery, radiation therapy, or a combination of these.

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SolveYourProblem.com : 2006

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