Where Melanoma Can Spread
If you have melanoma, one of the most important things to know is whether it has spread. The medical word for cancer that has spread is "metastasis." Melanoma is more likely to spread than other types of skin cancers. Over the past decade, the number of new melanoma cases per year continues to grow, yet overall survivorship has not changed. When caught before it spreads, melanoma is almost 100% survivable.
Melanoma starts when melanocytes—or pigment cells—near the surface of the skin begin to grow uncontrollably. Damage from the sun is the usual cause. Doctors grade melanoma in stages from 0 to 4. The stage you have depends on the thickness, depth and spread of the cancer. Stage 3 or 4 melanoma is cancer that has spread.
If you have stage 3 melanoma, you have cancer cells that have reached one or more of your lymph nodes. Lymph nodes are part of your body’s lymphatic system, which collects fluid from your tissues and returns it to your blood.
Melanoma can spread three ways:
- Direct spread to nearby tissues and areas, including the lymph nodes
- Through the lymph system to other parts of the body
- Through the bloodstream to other parts of the body
Whether your melanoma has spread will affect the type of treatment you will need. Your doctor may refer to your melanoma based on the spread of the cancer. There are three basic ways of explaining it:
- Localized disease is melanoma that has not spread to any lymph nodes.
- Regional disease is melanoma that has spread to one or more lymph nodes close to your cancer.
- Distant disease is melanoma that has spread beyond the lymph nodes close to your cancer to other parts of the body.
Whether your melanoma has spread will also affect the likelihood of survival. Doctors often use five years as a measure of how well people survive cancer. For melanoma, the five-year survival based on cancer spread breaks out like this:
- Localized disease has a five-year survival rate of about 98%.
- Regional disease has a five-year survival rate of almost 63%.
- Distant disease has a five-year survival rate of just over 16%.
Stage 4 melanoma is cancer that has spread to distant parts of the body. Another name for this is metastatic melanoma. It may have spread by growing into other areas of the body, or lymph fluid or blood may have carried it to other areas.
The cancer that forms in another part of the body will be made up of melanoma cancer cells. They will be similar to the ones that started on the surface of your skin. Stage 4 melanoma can involve almost any part of the body. The areas where melanoma most often spreads include:
Melanoma that has spread is much harder to treat and the five-year survival is much lower than earlier stages. That’s why it is so important to find it early, when melanoma is almost always curable.