How does Melanoma Spread?

Melanoma is a type of cancer. It develops in the cells that produce pigment, which is responsible for the skin's color. Melanoma is considered the most lethal of the cancers that affect the skin. Unfortunately, melanoma spread can cause cancer to move from the skin cells to the internal organs. Melanoma spread can also cause cancer to develop in a person’s lymph nodes.

Often, skin cancers do not spread; this is because they are basal cell carcinomas, which don’t usually spread. This type of skin cancer is often easier to cure. However, melanoma is different, and it spreads when cancerous cells get into the blood vessels near the melanoma or they make their way into lymphatic vessels. When the cells move into the blood vessels, they may be carried to other parts of the body, where they can develop in the organs. When they invade the lymphatic vessels, they are transported by the lymph fluid and drained, along with the fluid, into the lymph nodes.

Melanoma may be more prone to spreading to the lymph nodes that are nearest to the initial location of the cancerous cells. For example, a melanoma on an arm may be most likely to spread to the lymph nodes in the armpit. A melanoma on a person’s abdomen, however, is likely to cause cancer to form in either his armpit or his groin.

While any melanoma patient faces the risk of melanoma spread, a cancer that is less than 1 millimeter (.03 inches) thick may be located in just the top layers of the skin. In such a case, it may be less likely to spread, allowing a doctor to remove it and leave the patient free of cancer in some cases. Unfortunately, melanoma may reoccur, even after successful treatment. Additionally, a small percentage of these thin melanomas are not completely cured via surgical removal.

Often, melanoma spread moves cancer cells from the primary location of the tumor to the lymph nodes, from which they may move on to lymph nodes and organs that are further away from the initial site of the cancer. The treatment options for melanomas that have spread beyond the skin include surgical removal, chemotherapy, radiation therapy, and biological therapy. Patients in the earliest stage of melanoma, with cancers that have not spread or have not spread far, may have the best prognosis.

Once cancer has spread far across the body to distant organs and lymph nodes, it is referred to as stage IV melanoma. At this stage, there is less likelihood that the cancer can be cured. People at this stage often die because their organs eventually fail.