written by: N Nayab
• edited by: Emma Lloyd
• updated: 5/18/2011
Melanoma is a malignant type of skin cancer caused by the uncontrolled growth of melanocytes. It spreads rapidly to other body parts such as liver, lungs, brains, and bones, usually in five stages. As to how fast does melanoma spread, the rate of growth is unpredictable.
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Melanocytes, a layer of cells in the skin produce melanin, a brown-black skin pigment that determines skin and hair color and protect against the damaging rays of the sun. These melanocytes spread as the person ages and form clusters.
The controlled proliferation of melanocytes is non-cancerous and cause moles and freckles. At times, however the growth of melanocytes goes out of control and develops into cancerous and life-threatening melanoma. Such uncontrolled growth cause moles with uneven shape, dark color, or mixed color. The causes of such uncontrolled growth is usually excessive sun exposure during childhood, fair skin that burns easily, and certain hereditary conditions
A mole developing the following characteristics at a fast pace, within days or weeks could show melanoma:
Asymmetry, or both sides of the hole looking different
Border or moles with blurry or jagged edges
Color, or moles darkening, loosing color, or spotting multiple colors such as blue, red, white, pink, purple or gray
Diameter, or a mole larger than 1/4 inch in diameter
Elevation, or a mole raised above the skin and with a rough surface.
The bleeding or itching of such moles reinforces the possibility of melanoma. Apart from moles, speedy development of a scaly or crusted growth on the skin could also show spread of melanoma.
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Early Growth Stages
How fast does melanoma spread?
The rate of spread of melanoma is unpredictable, and depends on the severity of the disease and other contributing factors. While some people could live with melanoma for even 20 to 30 years without detection, other people encounter an advanced stage of melanoma within a few months.
The growth of melanoma is in five stages. The first three stages are usually not life-threatening, take a long time to spread, and is easily curable through surgery.
The melanoma tumor during its initial phase or Stage 0 is less than 1 millimeter (.03 inches) thick and remains confined to the top layer of the skin. This stage lasts the longest. During this stage, the melanoma is least likely to spread, and the chance of cure through surgical removal is at its highest.
Stage 1 melanoma is when the tumor grows below the first skin layer, but remains less than 1/8 inch thick This stage lasts anywhere between one and five years.
Stage 2 melanoma occurs when the tumor grows to 1/4 inch thick and extends to the lower layers of skin. The most visible symptom of the tumor growing downward is lesions becoming raised or dome-shaped. Melanoma becomes fatal from this stage onwards. The growth during this phase is unpredictable, but usually rapid, varying between weeks and months.
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Advanced Growth Stages
Stage 3 and Stage 4 melanoma, also called metastasis denote advanced stages of melanoma where the tumor spreads from the skin to other organs. Advanced melanoma prognosis indicate that surgical removal becomes difficult and chances of success rare.
Stage 3 melanoma is caused when the tumor grows out of the skin and spreads to the lymph nodes through the blood vessels. The rate of spread, tough unpredictable is usually faster than stage 2.
Stage 4 melanoma is the most advanced stage, and occurs when the tumor spread to multiple organs and all parts of the skin. It usually affects the liver first, followed by the lungs, brains, and bones.
Melanoma spreads first to the lymph nodes nearest to the initial location of the cancerous cells. For instance, melanoma on an arm spread to the lymph nodes in the armpit. Metastasis in the brain is the most advanced stage, and the average survival time of a person affected by brain melanoma is only about four months.
Melanoma spreads silently without any major symptoms until it develops into metastasis. How fast does melanoma spread depends on many factors:
The type of melanoma. Superficial type of melanoma that spreads out horizontally within the outside layer of skin and does not penetrate inside the body is easily curable by excision. Similarly, Lentigo maligna melanoma that occurs in the face grows very slowly. On the other hand, invasive melanoma, when the cancerous cells grow into the deeper layer of the skin and beyond is more dangerous and grows faster.
The grade of cancer, or the make-up of the abnormal cells. High grade cancer is the presence of tumors made of very abnormal cells that tend to grow and spread very fast. Low grade cancer consists of tumors made of cells only slightly different to normal cells, and tend to grow slowly, or may not spread at all.
Gene abnormalities. Melanoma begins as an uncontrolled proliferation of transformed melanocytic stem cells made possible by genetic changes that promote invasion into the surrounding tissue
A study in 2001 correlates the spread of melanoma in the skin to the presence of a skin-specific chemokine and a high level of corresponding chemokine receptors in melanoma cells. This study concludes that cancerous cells multiply only in areas that have appropriate cellular growth factors, or become glued to specific areas, or become attracted to specific areas by organ-specific molecules through "chemoattraction"
Removing the melanoma prevents the existing cancerous spot from spreading and does not stop the production of new malignant melanoma.