The Spread of Melanoma Metastasis

dermatologist looking at mole with light and magnifier

If you or a family member or friend have recently been diagnosed with melanoma, you may be wondering, just where and why can melanoma spread?

With surgery, melanoma confined to the skin is curable in 95 to 98 percent of cases. Unfortunately, if the lesion recurs (returns), gets thicker, or spreads from the skin to the lymph nodes or distant organs, it becomes much more dangerous. This occurs in stage III and IV melanoma and is called melanoma metastasis.

What Is Melanoma?

Melanoma, the most serious type of skin cancer, develops in the cells (melanocytes) that produce melanin—the pigment that gives your skin its color. Melanoma can also form in your eyes and, rarely, in internal organs, such as your intestines.

The exact cause of all melanomas isn't clear, but exposure to ultraviolet (UV) radiation from sunlight or tanning lamps and beds increases your risk of developing melanoma. Limiting your exposure to UV radiation can help reduce your risk of melanoma.

The risk of melanoma seems to be increasing in people under 40, especially women. Knowing the warning signs of skin cancer can help ensure that cancerous changes are detected and treated before cancer has spread. Melanoma can be treated successfully if it is detected early.

How Is Metastasis Detected?

If your doctor suspects that your melanoma may have spread, there are several tools available to verify the diagnosis. These include a blood test for lactate dehydrogenase (LDH), which increases when melanoma metastasizes, and imaging studies, such as chest x-ray, computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET) and ultrasound.

The doctor may also need to take a sample of your lymph nodes, using a procedure called "sentinel lymph node mapping." If confirmed, there are many treatments available, including chemotherapy, immunotherapy, radiation therapy and surgery.

Where Melanoma Spreads

Studies have shown that melanoma can spread to almost any area of the body—a wider variety of areas than any other cancer. The likelihood that it will spread to each organ is as follows:

  • Lymph Nodes: 70 to 75 percent
  • Other areas of the skin, fat, and muscle: 65 to 70 percent
  • Lungs and area between the lungs: 70 to 87 percent
  • Liver and gallbladder: 54 to 77 percent
  • Brain: 36 to 54 percent
  • Bone: 23 to 49 percent
  • Gastrointestinal tract: 26 to 58 percent
  • Heart: 40 to 45 percent
  • Pancreas: 38 to 53 percent
  • Adrenal glands: 36 to 54 percent
  • Kidneys: 35 to 48 percent
  • Spleen: 30 percent
  • Thyroid: 25 to 39 percent

Metastasis in the brain usually occur late in stage IV disease and carry the worst prognosis, with an average survival of only four months.

Can Metastasis be Prevented?

Melanoma can spread "silently," meaning that you may not experience any symptoms of metastasis. Therefore, if you've been treated for early-stage melanoma in the past, it is extremely important to perform regular self-examinations of your skin and lymph nodes, to keep all your appointments for checkups, and practice sun safety. There is nothing else an individual can do to prevent metastasis from being very diligent.

Catching a recurrence early greatly increases your chances of successful treatment. If the melanoma does spread, it is important to remain positive: remember that while the average prognosis is poor, some people do survive stage IV melanoma.

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Article Sources

  • King DM. Imaging of metastatic melanoma. Cancer Imaging. 2006;6:204-8. DOI: 10.1102/1470-7330.2006.0033

  • Mayo Clinic. Melanoma.

  • Melanoma: How It Returns, Where It Spreads. American Academy of Dermatology.