Risk Factors

Australia has the highest rate of skin cancer in the world. One in two Australians will develop some form of skin cancer during their lifetime. Each year more than 12,500 Australians are diagnosed with melanoma, the most serious form of skin cancer. It is important to know your risk.

Anyone can develop skin cancer, but the risk is increased for people who have:

• Fair Celtic skin – that burns easily, freckles and doesn’t tan easily
• A history of repeated episodes of sunburn and blistering, especially in childhood and adolescence
• Other close family members who have had melanoma
• Certain types of naevi (moles)

Melanoma Risk Factors

Complexion: Melanoma is more common in people with fair complexions as they have less skin pigment to protect them against UV radiation from the sun than people with darker skin. People with dark or olive skin have more protection against skin cancer because they produce more melanin than fair skinned people, however, because UV radiation is so strong in Australia dark and olive skinned people still need to protect their skin.

Age: Melanoma is diagnosed most often in older adults, but it also occurs in younger adults and occasionally in teenagers.  It is rarely seen in children, however repeated episodes of sunburn in childhood and adolescence can contribute to developing melanoma.

Mole count: People with a lot of moles have a higher risk of melanoma. Adults with more than 10 on the arms and more than 200 on the body should have their moles checked regularly by their GP.

DID YOU KNOW?

Melanoma in men is more common on the back, while women get more melanomas on their legs.

Relative Risk Factors

While UV exposure has been proven to increase the risk of melanoma there are other factors which can also greatly increase an individual’s chance of being diagnosed with melanoma. Risk factors contributing to melanoma are measured by their Relative Risk (usually referred to as RR).  A higher RR means a greater chance of developing melanoma. For example a history of non-melanoma skin cancer has a RR of 4 for melanoma. This means that if you have such a history, your chance of developing melanoma is 4 times greater than those who do not have a history of non-melanoma skin cancer.Relative Risk factors for melanoma include:

• Total number of naevi (moles).  This is the most important common independent risk factor. The RR for people with 25 to 50 naevi on their body is 4.4 while the RR for 100 or more naevi on the body is 9.8.
• Presence of atypical (dysplastic, or DN) naevi. In patients with DN syndrome the RR is very high. This becomes even higher when there is also a personal or family history of melanoma. The RR for people with 1 to 5 DN is 3.8 while the RR for people with DN syndrome is 17 to 47.
• Caucasian (Anglo-Celtic) races have a significantly increased risk compared with substantial low risk in Asian and dark-skinned races.
• A history of solar keratoses and non-melanoma skin cancer. The estimated RR for non-melanoma skin cancer is 4.
• Pale skin with poor tanning ability has an RR of 3.
• Early onset of living in an area of high ambient solar radiation. A low solar radiation environment prior to 10 years of age has an RR of 0.3.
• Having at least one first degree relative with melanoma. Only about 5% of melanomas occur in a true melanoma family-prone setting. About 20% of these families have mutations in the p16/CDKN2A gene. The RR of melanoma is 2.2 for individuals who have a family history of melanoma.
• History of sunburn at any age has a RR of 1.9.
• Non-occupational "intermittent" sun exposure has a RR of 1.7.
• Freckling skin has an RR of 1.5.
• Personal history of melanoma increases the risk of a second melanoma.  Australian figures estimate a 12% chance of developing a second melanoma within 10 years of the first diagnosed.
• Increasing age. Melanoma is rare prior to puberty and increases in incidence with age.
• Large congenital naevi (> 20cm or 5% of total body area): RR = 10.1, even in cohorts where more than half of patients' lesions are partly or completely excised.