Certain people are at a higher risk than others of developing skin cancer. A person’s risk for developing skin cancer depends largely on two groups of factors – genetic and environmental.
These are the individual’s family history and their inherited genes, so a person who has a family history of skin cancer is more likely to develop cancer themselves because of the genetic factors involved.
Genes also determine individual traits such as hair colour, eye colour, skin colour, and numbers of moles and freckles. Each of these traits is linked to the risk of developing skin cancer, for example, melanoma is less common in people with dark skin than in people with fair skin.
The most relevant environmental factor is sun exposure. UV radiation causes damage to the DNA of cells, which, if not repaired, can create mutation in the genes. Both cumulative sun exposure to UV and incidences of sunburn have been linked to different types of skin cancer.
The intensity and length of sun exposure, the age at which the sun exposure occurs and the colour of skin all affects the chances of developing skin cancer. Exposure to environmental factors is influenced by our behaviour (such as sport and leisure activities outdoors) and our attitudes (how important we think it is to protect our skin and what steps we are prepared to take to do that).
Who is most at risk?
People with the highest risk include those who have:
- a large number of moles or freckles
- unusual moles
- a history of sunburn
- fair skin and/or red hair
- had a skin cancer before
- had an organ transplant, or a suppressed immune system.
People who have had one skin cancer are at much higher risk of developing another. For example, people with a basal cell carcinoma have an almost 30% chance of developing another skin cancer in the next three years.
However, skin cancer can develop in anyone, not only people with these risk factors.
Nature of Science
When scientists talk about what they have found out, they often state their findings as percentages or the probability that such an event may occur. The language of mathematics can be very helpful in explaining and understanding scientists’ predictions.
How can we reduce our risk?
Early detection and prevention of excessive sun exposure are the best ways to reduce risk.
Early detection and diagnosis is the key to successful treatment and to reducing the impact of scars from surgery. It is important to check your skin regularly for any changes (such as new or changed freckles or moles, or sores that don’t heal) and visit a doctor with any concerns.
It is useful to remember the ABCDE mnemonic for melanoma:
According to the Cancer Society of New Zealand the most significant way to reduce risk is to protect yourself from the sun during peak UV radiation periods, from September to April, especially between 10am and 4pm when the UV levels reach their peak.
- Seek shade between 10am and 4pm. Being in the shade can reduce overall exposure by about 75%.
- Do not burn. New Zealand research suggests that a 10% reduction in the number of people who have blistering sunburn could prevent 28 cases of melanoma per year in New Zealand.
- Cover up with a broad-brimmed hat, clothing, sunglasses and sunscreen.
- Wear a broad spectrum sunscreen that blocks both UVA and UVB radiation.
- Take particular care when you are near reflective surfaces like snow, water or sand, by wearing sunscreen on you face, even while wearing a hat.
- Do not use sunbeds or sunlamps.
This DermNet NZ web page looks at sun protective clothing.
This Skin Cancer Foundation web page looks at skin types and at risk groups.
The SunSmart Schools website is designed for students, teachers, schools and parents. It has information about UV, shade, hats, sunscreen, skin cancer and sun protection, as well as cross-curricula resources for teachers at levels 1 to 4 of the New Zealand Curriculum.
Results released in 2018 from the Wellington Kids’Cam study by the University of Otago, show that people need to wear sun hats and stay in the shade a lot more.