Non-melanoma skin cancer and the sun
The leading cause of skin cancers is exposure to the sun, which may be long-term exposure, or short periods of intense exposure to ultraviolet light.
In fact, it is the ultraviolet light from sunlight or lamps than damages the skin cells, often years before a cancer develops.
Several factors affect your risk from sun exposure:
- the amount of time you spend outdoors
- your natural skin colour
- how much you use sunbeds (a source of artificial UV radiation).
If you have a history of sunburn or exposure to sunlight then there’s an increased risk of BCC, and the risk is especially high if you’ve had several episodes of sunburn in childhood.
The risk of SCC is mainly connected with overall sun exposure throughout your life, which is also a factor with BCC, but to a lesser degree. This means outdoor workers such as farmers, gardeners and building site labourers can have an increased risk of non-melanoma skin cancer.
Fair skinned people with light coloured hair and eyes, or those people who are more likely to burn than tan, are more at risk of skin cancer. This is because fairer skin makes less of the protective pigment called melanin.
Albinism is an inherited genetic condition where the skin makes no melanin at all, so there is a higher than average risk of skin cancer because the skin has no natural protection against the sun.
We know that using sunbeds (a source of artificial UV radiation) can cause melanoma, but there is now evidence that they may increase the risk of non-melanoma skin cancer too, in particular squamous cell skin cancers.
BCC and SCC develop very slowly. As you get older you have more time to build up sun damage to your skin. So the older you are, the more likely you are to develop a non-melanoma skin cancer. But skin cancers can develop in younger people too.
If you’ve had skin cancer before
Your risk of getting a non-melanoma skin cancer increases by about 10 times if you’ve had one before, compared to if you’ve never had a skin cancer before.
If you’ve had a melanoma, then you have a three times higher than average risk of developing a non-melanoma skin cancer.
And, if you’ve had a non-melanoma skin cancer before, you may also be at increased risk of developing a second cancer, other than skin cancer.
Also, some studies show that people who’ve had a non-melanoma skin cancer have about double the risk of melanoma compared to the general population.
Most non-melanoma skin cancers don’t run in families, but some research suggests a few families seem to have a higher number of skin cancers than normal.
People with a family history of melanoma may have an increased risk of BCC. And, if you have a parent who’s had squamous cell skin cancer, you have a two to three times higher than average risk of getting one yourself.
People from fair skinned families will be more at risk, because their skin is more sensitive to UV rays. And there may be inherited genes that increase the risk of skin cancer in some families.
The following skin conditions can increase the risk of developing a skin cancer:
Psoriasis is not a risk in itself, but some of the treatments (such as ultraviolet light) may increase your risk.
Scarring from burns or skin ulcers, can make your skin more at risk from sun damage, which may increase your risk of non-melanoma skin cancer.
Solar keratosis, also called actinic keratosis, is a skin condition caused either by years of exposure to the sun, or by a period of intense sun (or artificial ultraviolet radiation) exposure on fair skin.
Xeroderma pigmentosum is a rare inherited genetic skin condition, which also has a rare variant of this condition called xeroderma pigmentosum that doesn’t show up until adolescence. With this condition, the skin can’t repair damage from the sun, so all sun exposure and other sources of UV light should be avoided. However, even with these precautions, people with this rare condition may often get skin cancers on exposed skin.
Gorlin syndrome, also called naevoid basal cell carcinoma syndrome, is a rare inherited genetic condition that causes multiple BCCs to develop.
Eczema, its commonest type called atopic dermatitis, may increase the risk of non-melanoma skin cancer, and some people with chronic eczema who have ultraviolet light treatment with a drug called methoxsalen (a type of psoralen) means an increased risk of non-melanoma skin cancer.
However, another type of eczema, called contact dermatitis, may actually slightly reduce the risk of non-melanoma skin cancer.
Past radiation exposure
If you’ve had radiotherapy before, the area that was treated will be more at risk of non-melanoma skin cancer. Also, if you’ve been exposed to any kind of radiation through your job or lifestyle, you may have a slightly increased risk of non-melanoma skin cancer.
Weakened immune system
If you’ve had an organ transplant or a bone marrow transplant and are taking drugs to stop rejection, you have an increased risk of developing skin cancer, and the risk increases the longer you take these drugs. However, this risk may be less important than the illness you had treatment for originally – but it helps to know so that you can watch for any symptoms of skin cancer early on, when it is easier to treat.
People with HIV or AIDS, who also have a weakened immune system, may also have an increased risk of non-melanoma skin cancer.
People with diseases such as inflammatory bowel disease or rheumatoid arthritis can have an increased risk of skin cancer, which may be due to the condition itself and/or the medications taken to suppress the immune system.
Human papilloma virus (HPV)
This is common virus has several different strains, and some studies show that a number of non-melanoma skin cancers contain DNA from certain types of HPV. Also, one study has shown that people with genital warts (caused by HPV types 6 and 11) may have an increased risk of basal cell skin cancer.
Prolonged or frequent skin contact with certain chemicals may increase your risk of non-melanoma skin cancer, and these include coal tar, soot, pitch, creosote, shale oils, arsenic and petroleum products, such as mineral oil or motor oil.