Cancer happens when cells divide without control or order. These cells grow together to form a tumor. They can invade and damage nearby tissues. They can also spread to other parts of the body.

It is not clear what causes changes in the cells. It is likely due to genes and environment.

Risk Factors

Melanoma is more common in men and those aged 40 to 60 years old. However, younger people can also get it.

Things that raise the risk of melanoma are:

  • Moles called dysplastic nevi, or atypical moles
  • Having many moles
  • Having:
    • Light skin and a tendency to have freckles
    • Red or blonde hair
    • Blue or green eyes
  • A family history of melanoma
  • Excessive skin exposure to the sun—without protective clothing or sunscreen
  • Using sun lamps and tanning booths
  • A history of childhood cancer, skin cancer, or skin pre-cancer
  • A weak immune system



Melanomas are not usually painful.

Symptoms may be a change in the size, shape, color, or feel of an existing mole. Melanoma may also appear as a new, dark, discolored, or abnormal mole.

Signs that a mole may be melanoma are (ABCDE rule):

  • Asymmetry or uneven shape—one half does not match the shape of the other half
  • Border or edges are uneven
  • Color varies or is uneven—with shades of black, brown, white, gray, pink, red, or blue
  • Diameter or size—often larger than a pencil eraser (6 millimeters or ¼ inch)
  • Evolution or change—often grows larger; changes shape, color, or texture, or may itch

Some melanomas do not fit the ABCDE rule.

Sign of Potential Melanoma
Skin Cancer Sign: Irregular Border on Mole
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The doctor will ask about symptoms and past health. A physical exam will be done. The doctor will look at the skin and moles. A tissue sample of the area will be taken and tested for cancer.

The doctor may also check lymph nodes. Swollen lymph nodes could mean melanoma has spread. A sample of lymph node tissue may also be removed for testing.

If melanoma is found, more tests will find the stage of cancer. Melanoma is staged from I to IV. Staging shows if the cancer has spread.



Treatment will depend on the location and stage of the melanoma. One or more treatments may be used, such as:

  • Surgery to remove the melanoma and some tissue around it
  • Sentinel lymph node biopsy—lymph nodes near the tumor may be removed for testing or to stop the spread of cancer
  • Chemotherapy—drugs to kill cancer cells, if cancer has spread
  • Other medicines such as:
    • Immunotherapy—to help the immune system fight cancer
    • Medicines to target cells with the BRAF gene—a gene that makes melanoma grow fast
  • Radiation therapy—to kill cancer cells and shrink tumors


To help lower the risk of melanoma:

  • Do not spend too much time in the sun
  • Protect skin from the sun:
    • Wear a long-sleeved shirt and long pants, a wide-brim hat, and sunglasses
    • Use sunscreens with an SPF of at least 30
    • Avoid exposure during the peak hours of the day
  • Do not use sun lamps and tanning booths

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.