What causes skin cancer?

The vast majority of skin cancers are caused by exposure to ultraviolet light in the form of sun exposure but also from artificial sources such as solariums and arc welding.  Other causes of skin cancer include exposure to cancer causing chemicals such as arsenic, or ionising radiation.  These causes are much less common than ordinary sunburn from the sun.  There are many types of skin cancers. Many Australians are burnt on a regular basis, and sunburns are often associated with outdoor activities we spend our leisure time doing, such as outdoor sports, gardening and swimming.  Many outdoor workers are also burnt frequently although workplace health and safety preventionhas helped to some degree.

Sun damage at a young age is potentially the most dangerous, because the skin is thin and delicate and may burn more easily.  It is also the time when sunburn is most likely to result in freckling and mole formation, which are both markers for people at risk of future skin cancers.  In fact, a mole count over forearms is an indication of future melanoma risk, with high mole counts being associated with increased lifetime risk of melanoma.  Children need to be protected from sun damage and in particular sun burn with hats, sunglasses, protective clothing (shirts, rash vests), high potency sunscreens (50+ SPF recommended) and avoidance sun exposure in the hottest part of the day.  Every sunburn contributes to an increased risk of skin cancer in future and there may be a very long (decades) delay before the skin cancer appears.  Skin cancers occurring after a single sunburn has been documented, with a delay of 40 years between the sunburn and the eventual cancer formation. Regular sunscreen application for skin types susceptible to sun burn can prevent accidental sunburns, and lead to a reduced risk of future skin cancers.

Most children are at very low risk of skin cancers, so regular skin checks are not routinely recommended unless there are particular concerns.  While skin cancers including melanoma are rare, they do occur, so if there is a mole or spot that is changing or growing at an accelerated rate, or looks odd or different to every other mole on the child’s body, then they should be checked to ensure it is not a cancer.

Sunspots, which are also called solar or actinic keratoses, are pink or tan coloured scaly spots that feel slightly rough to the touch. They occur commonly in people over 40 with light skin and hair/eyes and on skin that’s often exposed to the sun.  Most common areas are the face, tips of the ears, back of hands and forearms. 

Sunspots can be a warning sign that you’ve spent too much time in the sun without appropriate sun protection, and indicate that you have a higher risk of developing skin cancer in the future.

Squamous cell carcinoma can develop from solar keratosis.  If your sun spot feels thicker and slightly raised off the surface of the skin, it may be an indication that it has progressed from solar keratosis to intraepidermal squamous carcinoma (IEC) which is a superficial form of squamous cell carcinoma (SCC). 

Solar keratosis is often treated with destructive treatments to individual lesions, such as cryotherapy (freezing treatment) or with a field treatment to the area.  Individual destructive treatments are usually used if there is a limited number of discrete spots to treat, and has the advantage of being cheap and quick.  Field treatments are usually used when there is a large area affected by large numbers of solar keratosis lesions or when the entire area is affected to some degree with solar keratosis and individual treatment is not practical.  Field treatments include Efudix, Photodynamic Therapy (PDT), Aldara, Solaraze or Picato.

Melanoma Scan - Skin Cancer Clinic

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