Skin Cancer Causes

By Dr Ananya Mandal, MD

There are several risk factors that raise the propensity to get skin cancers by manifold. The exact cause why DNA damage occurs and why cancer results from such DNA damage is not known clearly but these risk factors give an idea regarding factors that can be avoided to prevent skin cancers.

Risk factors of skin cancers

The risk factors of skin cancers include:-

Exposure to sunlight

One of the major risk factors for skin cancer is exposure to sunlight (UV radiation). This is particularly true for basal cell and squamous cell cancers that occur in exposed parts of the skin.

Sunlight is a source of UV radiation. This UV radiation exposure leads to damage to the DNA of the cells of the skin. DNA damage is the underlying cause of any type of cancer.

Sunlight exposure may be direct or may be indirect. Indirect exposure results from reflected sunrays by sand, water, snow, ice and shiny surfaces like glass etc. The sun exposure is also high at higher elevations, such as in the mountains. The sun's rays can penetrate through clouds, windshields, windows and even light clothing. In the United States skin cancers are more common where the sun is strong e.g. in Texas.

Those with a propensity for severe sunburns and blisters on exposure to sunlight are at a heightened risk of skin cancers. People who burn easily are more likely to have had sunburn as a child. The total amount of sun exposure over a lifetime is a risk factor for skin cancer. Those exposed to the sun excessively during childhood are at greater risk. It is found that most of the sun’s UV radiation exposure occurs before the age of 18 years.

Studies have shown that a tan slightly lowers the risk of sunburn but the risk remains. People who tan little or not at all and burn more when exposed to sun are more at risk of skin cancers.

Exposure to Sunlamps and tanning booths

These are artificial sources of UV radiation that can cause sun damage to the skin and may raise the risk of skin cancers. Health care providers strongly encourage young individuals especially to avoid using sunlamps and tanning booths. The risk is high in users of sunlamps and tanning booths before the age of 30.

Family history of skin cancer

Those with a family history of skin cancers are at a raised risk of skin cancers. Melanoma sometimes runs in families. Having two or more close relatives or first degree relatives (parents, siblings or offspring) raises the risk of melanoma. Other types of skin cancer also sometimes run in families. Those with a family history of xeroderma pigmentosum or nevoid basal cell carcinoma syndrome have a skin that is more sensitive to the sun and increases the risk of skin cancer.

Previous melanoma

Individuals who have had a melanoma before are at a greater risk of getting it again.

Age and sex

Men are more susceptible to both melanoma and non-melanoma skin cancers. Melanomas can be found in younger people but the rates of all types of skin cancer rises with increasing age.

Skin colour

Individuals with fair or pale skin, especially with blonde, red or light-brown hair and blue, green or gray eyes are at a raised risk.

Certain medications

Some diseases and medications such as some antibiotics, hormones, or antidepressants may make the skin more sensitive to sun exposure and raise the risk of skin cancers.

Dysplastic nevus

Individuals with a dysplastic nevus are at a raised risk of getting melanoma. This is a type of a mole that looks different from a common mole. It is bigger, and its edges, structure, surface etc. may be different. It may be longer and wider with patches of several colors ranging from shades of pink to dark brown. The surface is smooth, scrappy or pebbly and edges are rough and blurred. A dysplastic nevus is more likely than a common mole to turn into cancer.

Over 50 moles on the body

Individuals with more than 50 moles on their body are more at risk of melanomas.

Old large scars

Presence of old large scars, ulcers, burn marks and skin inflammations raise the risk of squamous cell cancers and basal cell cancers.

Arsenic exposure

Arsenic exposure raises the risk of basal cell or squamous cell cancers.

Radiation exposure

Radiation exposure to skin for other cancers may damage the skin to cause cancers.

Actinic keratosis

Those with Actinic keratosis (a flat, scaly growth on the skin in the exposed areas such as face and the backs of the hands) are at a raised risk of squamous cell cancer.

Human papillomavirus (HPV)

Exposure to human papillomavirus or HPV also raises the risk of squamous cell skin cancer. These HPVs are different from the HPV types that cause cervical cancer in the female reproductive tract.

Reviewed by , BA Hons (Cantab)

Further Reading

Last Updated: Jan 21, 2013

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