Skin Cancer, Melanoma

What Happens

Melanoma develops when normal pigment-producing skin cells called melanocytes become abnormal, grow uncontrollably, and invade surrounding tissues. Usually only one melanoma develops at a time. Although melanomas can begin in an existing mole or other skin growth, most start in unmarked skin. Melanoma is classified as primary or metastatic.

Primary melanoma

Primary melanoma usually follows a predictable pattern of growth through the skin layers. Early detection and surgery to remove the melanoma cure most cases of primary melanoma.

If not treated, most melanomas spread to other parts of the body over time. Melanomas rarely go away without treatment.

Your long-term survival, or prognosis, with primary melanoma depends on:²

• How deeply the melanoma penetrates the skin (melanoma thickness).
• Whether an open sore is present over the primary tumor (ulceration).

Metastatic melanoma

Metastatic melanoma has spread through the lymph system to nearby skin, lymph nodes, or through the bloodstream to other organs such as the brain or the liver. Metastatic melanoma usually cannot be cured. Early detection and removal of primary melanomas before they metastasize offer the best hope for cure.

Experts talk about prognosis in terms of "5-year survival rates." The 5-year survival rate means the percentage of people who are still alive 5 years or longer after their cancer was discovered. Remember that these are only averages. Everyone's case is different, and these numbers do not necessarily show what will happen to you. The estimated 5-year survival rate for melanoma is:³

• 99% if cancer is found early and treated before it has spread.
• 65% if the cancer has spread to close-by tissue.
• 15% if the cancer has spread farther away, such as to the liver, brain, or bones.

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Author:	Bets Davis, MFA	Last Updated: December 5, 2008
Medical Review:	Kathleen Romito, MD - Family Medicine Alexander H. Murray, MD, FRCPC - Dermatology
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