Causes and risk factors of melanoma
The biggest risk factor for melanoma is exposure to ultraviolet light (UV light). This can be through sunlight or sunbeds.
What are risk factors?
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Ultraviolet light exposure (UV exposure)
In the UK, the number of white people developing melanoma and other skin cancers is rising. One of the reasons for this is people having more UV exposure through sunlight. But better awareness of melanoma means more people are being diagnosed with early melanoma.
Melanoma is linked to short periods being exposed to strong sunshine through sunbathing or holidays in hot countries. Other skin cancers are more linked to ongoing sun exposure – for example, from working outdoors for many years.
Sunlight
Is melanoma caused by the sun?
In the UK, the number of white people developing melanoma and other skin cancers is rising. One of the reasons for this is people having more UV exposure through sunlight. But better awareness of melanoma means more people are being diagnosed with early melanoma.
Melanoma is linked to short periods being exposed to strong sunshine through sunbathing or holidays in hot countries. Other skin cancers are more linked to ongoing sun exposure – for example, from working outdoors for many years.
Sunburn
Regular episodes of sunburn, especially severe sunburn that causes blistering, increases the risk of melanoma. This is whether you had sunburn as a child or as an adult. It is important to protect your skin from too much sun.
Sun exposure and getting enough Vitamin D
Getting a small amount of sunshine on a regular basis as well as eating certain foods helps our bodies make vitamin D. This keeps our bones and teeth healthy. It also helps our immune system and has some anti-cancer effects. The amount of sun exposure you need depends on:
- your skin type – if you have black or brown skin, you need more sun exposure than someone with white skin
- the time of year – in the UK, you do not get enough sunlight from October to early March to make vitamin D through sun exposure.
You do not need to sunbathe, tan or burn to make enough vitamin D to keep healthy. If you have melanoma, you can ask your doctor about having your vitamin D levels tested.
Sunbeds
Sunbeds use artificial UV rays that also damage the DNA in your skin. They increase the risk of melanoma. The more you use a sunbed or sunlamp, and the younger you are when you start using one, the higher the risk.
It is important not to use sunbeds, especially if you have:
- had melanoma or any skin cancer
- an increased risk of melanoma.
Your skin type
If you have the type of skin that burns more easily, you are more at risk of melanoma. You are more sensitive to the sun if you have:
- fair skin
- red or blonde hair
- green or blue eyes
- freckles.
Having freckles means a higher risk of melanoma, whether you have moles or not.
Ethnicity
If you are Black or Asian, you have a lower risk of melanoma because your skin produces more melanin. But it does not mean that you cannot get skin cancer. You still need to protect your skin from the sun and check for anything unusual.
A type of melanoma called acral lentiginous melanoma is more common in people with black or brown skin. It starts in skin that is not usually exposed to sun.
Age
Being older is one of the main risk factors for melanoma. Damage to the DNA in the melanoma cells caused by risk factors builds up over time.
More than a quarter of people diagnosed with melanoma are over 75. But melanoma is also more common in younger people than some other cancers. Women in their 20s are more likely to develop it than men of the same age. Melanoma can also affect teenagers, but this is not common.
Having lots of moles and unusual moles
If you have lots of moles or unusual moles, you can be referred to a skin specialist (dermatologist). They will do an assessment of your skin and give you advice.
You have a higher risk of melanoma if you have:
- lot of moles, especially over 100 moles
- moles that are bigger than average and are an irregular shape or colour.
Having lots of moles or irregular moles can run in some families.
If you were born with a mole (congenital mole)
Having a congenital mole or naevus increases the risk of melanoma. A congenital mole is when you are born with a large birth mark (over 20cm) or with a dark, hairy mole. The risk from average-size birth marks is very small.
Family history of melanoma
The risk of developing melanoma increases if you have a close relative who has had melanoma. A close relative (or first-degree relative) is your mother, father, sister, brother or child. This may be because you have a similar skin type. But about 1 in 10 melanomas (10%) are thought to be caused by genes that can run in families.
The risk is highest if:
- your relative who had melanoma is under 30
- you have more than 1 first-degree relative with melanoma.
If you have a family history of melanoma, you may be referred to a genetic counsellor to talk about having a genetic test. The test looks for a gene called p16 that can increase the risk of melanoma. This gene may also be linked to pancreatic cancer. Your genetic counsellor will talk to you about this. Like all cancers, melanoma may also be caused by a number of genes we cannot test for yet.
If you have a strong family history of melanoma, your GP can refer you to a dermatologist and a family cancer clinic.
We have more information on cancer genetics.
Reduced immunity
Having a weakened immune system can increase the risk of melanoma.
This includes people:
- with HIV or AIDS
- with inflammatory bowel conditions such as Crohn’s disease
- taking drugs to suppress the immune system, for example after an organ or stem cell transplant.
About our information
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References
Below is a sample of the sources used in our melanoma information. If you would like more information about the sources we use, please contact us at cancerinformationteam@macmillan.org.uk
Michielin O, van Akkooi ACJ, Ascierto PA, et al. Cutaneous melanoma: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Annals of Oncology. 2019; 30, 12, 1884-1901 [accessed May 2022].
Michielin O, van Akkooi ACJ, Ascierto PA, et al. ESMO consensus conference recommendations on the management of locoregional melanoma: under the auspices of the ESMO Guidelines Committee. Annals of Oncology. 2020; 31, 11, 1449-1461 [accessed May 2022].
Peach H, Board R, Cook M, et al. Current role of sentinel lymph node biopsy in the management of cutaneous melanoma: A UK consensus statement. Journal of Plastic, Reconstructive & Aesthetic Surgery. 2020; 73, 1, 36-42 [accessed May 2022].
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Reviewers
This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Senior Medical Editor, Dr Samra Turajlic, Consultant Medical Oncologist.
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