Melanoma, causes & risk factors

What is melanoma?

Melanoma develops from melanocytes (pigment cells). Melanoma usually occurs on parts of the body that have been sunburned. However, melanomas can sometimes start in parts of the skin or other parts of the body that have never been exposed to the sun.

If detected early, most melanomas are curable.  

If melanomas are not detected until later, they can become more serious.

A melanoma may appear as a new spot on normal skin, or develop from an existing mole. Melanomas usually begin as a flat spot that changes in size or shape or colour over months. While they remain flat they are generally curable. They usually remain flat for six to 12 months. Later, melanomas become bigger, irregular in shape and often darker in colour. A less common type of melanoma (called nodular melanoma) is not flat, but is raised from the start. These melanomas are often pink or red, and grow quickly. Not all melanomas are dark or black in colour.

Visit the Cancer Council website to learn more about the different types of skin cancer and causes.

Melanoma causes

People can be at greater risk of melanoma if they have one or more of the following:

• large numbers of moles
• large, irregularly shaped and unevenly coloured moles called dysplastic naevi
• previous melanomas
• many severe sunburns
• other people in the family who have had melanoma (a ‘family history’)

Each time your unprotected skin is exposed to the sun’s UV radiation or other sources of UV radiation such as solariums, the UV radiation causes changes to take place in the structure of the cells and in what they do.

Too much UV radiation causes the skin to become permanently damaged. The damage worsens with more UV radiation. The most important years for sun protection are during childhood. Sunburn and overexposure to UV radiation during these years greatly increase the chance of melanoma.

Melanoma is common in people with naturally fair complexions who are exposed to higher levels of UV radiation than their skin can protect them against. People with naturally darker skins (for example, Australian Aborigines and Torres Strait Islanders) are much better protected against UV radiation but can still get melanomas.

Australia has the highest rate of skin cancer in the world. Each year about 1,700 people in Victoria are diagnosed with melanoma. Melanoma is diagnosed most often in older adults, but it also sometimes occurs in younger adults and occasionally in teenagers. It is rarely seen in children.        

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