A risk factor is anything that increases a person’s chance of developing a specific disease. The most common cause for all skin cancers (non-melanoma and melanoma) is excessive exposure to the sun.

People whose occupations or lifestyle habits keep them exposed to the sun (or indoor tanning lamps) are at the greatest risk. People with fair skin, light eyes or light hair color are also at higher risk for developing non-melanoma skin cancer. Those who have darker skin tones are at lower risk for skin cancer, but if it occurs it is more likely to metastasize.

Other general risk factors include the following:

• Gender. Men are more likely to develop skin cancer than women, but this may be attributed to increased sun exposure.
  
  
• Chemical exposure. Contact with carcinogens (cancer-causing substances), such as arsenic, industrial tar, coal, paraffin, some petroleum byproducts, creosote (a wood preservative) and radium increases the risk of non-melanoma skin cancer.
  
  
• Skin inflammation or injury. Burns, scars, and skin conditions such as eczema can increase risk. Tattoos also make the skin more vulnerable.
  
  
• Family history of skin cancer. A family history of nonmelanoma skin cancer increases an individual’s risk of developing it.
  
  
• Personal history of skin cancer. Once a person has had a non-melanoma skin cancer, the risk of developing another is increased.
  
  
• Reduced immunity. This includes individuals infected with HIV, those who have full-blown AIDS or those taking immunosuppressive therapy (medications that may suppress the immune system).
  
  
• Living in a sunny or high-altitude climate. Those who live along the Sunbelt and those who live at high altitudes that have less than normal amounts of atmosphere for protection have an increased risk of developing skin cancer.
  
  
• Tobacco use. Any type of tobacco use, particularly smoking cigarettes, increases a person’s risk of many types of cancer, including most forms of skin cancer.
  
  
• Actinic keratosis. This skin condition may lead to squamous cell carcinoma in a small number of individuals. It is also related to sun exposure.
  
  
• Some psoriasis treatments are said to increase the risk of developing non-melanoma skin cancer.

In addition to general risk factors for non-melanoma skin cancer, there are also genetic syndromes that may predispose a person to developing this common form of cancer. These include:

• Xeroderma pigmentosum. A rare, inherited condition that impairs the body’s ability to repair DNA damage caused by sunlight.
  
  
• Albinism. A rare, inherited condition in which a person is born without pigment in the skin or hair.
  
  
• Nevoid basal cell carcinoma syndrome. A rare genetic disorder characterized by a predisposition to cancer, especially basal cell carcinoma before the age of 20, and other birth defects.
  
  
• Epidermodysplasia verruciformis. A genetic disease characterized by distinctive changes in the skin on the chest and arms and numerous warts on the hands and feet.