Skin cancer risk factors
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.
Risk factors for melanoma
Dr Elizabeth Baird, outlines the relationship between UV, melanocytes in the skin, tanning and melanoma risk. She discusses the risk factors of skin type and family history in the development of melanoma.
Select here to view video transcript and copyright information.
Genetic factors
Genetic factors are the individual’s family history and their inherited genes. The risk of melanoma can be higher in families where certain gene changes are passed down through the generations. When melanoma develops in this way, it is often referred to as inherited or ‘familial’ melanoma.
Scientists have identified that mutations of the CDKN2A gene is the most common cause of inherited melanoma. CDKN2A is a gene that regulates cell division.
A family history may be suspected when two or more close relatives — such as parents or siblings — are diagnosed with melanoma. About 10% of melanomas are familial.
Genes also determine individual traits such as hair colour, eye colour, skin colour, and the number 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.
Skin types
Different skin types have different risks of developing cancer.
Environmental factors
The most relevant environmental factor is sun exposure. UV radiation causes damage to the DNA of cells, which, if not repaired, can create mutations 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 affect the chances of developing skin cancer. Exposure to environmental factors is influenced by our behaviour (such as outdoor work, sport and leisure activities) 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.
Science uses conventions to communicate
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.
Reducing the risks
Dr Elizabeth Baird, a specialist dermatologist at Remuera Dermatology, discusses ways you can reduce your risk of developing melanoma. The risks of sunbeds are highlighted.
Select here to view video transcript and copyright information.
Early detection
Early detection and diagnosis are 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:
Asymmetrical
Border
Color
Diameter
Evolution
Melanoma check chart
The Melanoma ABCDE detection system is useful for tool for checking for possible melanomas.
Some charts also include an 'F' for 'firm to touch' or 'funny looking' and a 'G' for growth.
It is not foolproof because some melanomas do not have any of these more common characteristics. If you have any doubts about a change in your skin you should always see a doctor.
Gajera, Himanshu & Zaveri, Mukesh & Nayak, Deepak. (2022). Patch‐based local deep feature extraction for automated skin cancer classification. International Journal of Imaging Systems and Technology. 32. 10.1002/ima.22729.
Prevention
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. These periods occur from September to April, especially between 10 am and 4 pm when the UV levels reach their peak.
Seek shade between 10 am and 4 pm. 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 your face, even while wearing a hat.
Do not use sunbeds or sunlamps.
Sunburned and peeling arm
Sunburned and peeling arm showing evidence of sun damage. Damage like this can increase the risk of developing skin cancer.
The article UV and sunbeds explains local legislation and guidelines regarding sunbeds.
Related content
These related articles explain more about skin cancer, why NZ skin cancer rates are so high, and how skin cancer is diagnosed and treated.
Activity idea
The face of melanoma is an activity that looks at lifestyle factors that contribute to skin cancer.
Follow this with activities using the popular UV beads: UV bead items, Investigating UV intensity and Investigating sunscreens.
There is also a unit plan covering this aspect of UV.
Useful links
DermNet NZ provides an explanation of the CDKN2A gene and inherited risk of melanoma in Genetics of Melanoma and it looks at sun protective clothing.
This Skin Cancer Foundation web page looks at skin types and at risk groups.
The SunSmart 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 in the SunSmart Schools section.
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.
We know that prevention is an important component to reduce incidents of skin cancer in New Zealand, however a 2025 Health survey shows attitudes to sun protection, skin cancer slipping.
This HealthMatch article, Top 20 skin cancer hot spots in the world and why they're on the list, explores the roles that personal, cultural, and global habits play in rates of skin cancer and what we can do to change them.
Te Aho o Te Kahu Cancer Control Agency is a government agency created in recognition of the impact cancer has on the lives of New Zealanders.
