Skin Cancer Risk Factors
No one knows exactly what causes skin cancer, but it can occur in almost anyone. Unfortunately, the number of new cases of skin cancer in the United States has been increasing for at least 30 years, maybe due to increased sun exposure and tanning beds. Skin cancer is also becoming more common in younger people.
A risk factor is anything that increases your chance of getting cancer. Some risk factors, like sun exposure, can be controlled. Others, such as your gender, can't be changed. But risk factors don't tell us everything. Having a risk factor, or even many risk factors, does not mean that you will get the disease. And some people who get the disease may not have any known risk factors. Even if a person with skin cancer has a risk factor, it is often very hard to know what role that risk factor may have played. But research has shown that people with certain risk factors are more likely than others to develop the disease.
Primary risk factors for non-melanoma skin cancer are listed below.
Excessive UV/Sun Exposure
Too much exposure to UV radiation is thought to be the biggest risk factor for most skin cancer. The main source of UV light is the sun. Tanning lamps and booths are also sources of UV light. People with high levels of exposure to UV light are at greater risk for all types of skin cancer.
The amount of UV exposure depends on the strength of the light, how long the skin was exposed and whether the skin was covered with clothing and sunscreen. Many studies also point to exposure at a young age (for example, frequent sunburns during childhood) as an added risk factor.
Those who work outdoors or have outdoor recreational habits, live near the equator, have had prior therapy with UV light and have an elevated socio-economic status are at the greatest risk for skin cancer.
The risk of skin cancer is much higher for whites than for African-Americans or Hispanics. This is due to the protective effect of melanin (skin pigment) in people with darker skin. Whites with fair (light-colored) skin that freckles or burns easily are at especially high risk. This is another reason for the high skin cancer rate in Australia, where much of the population descends from fair-skinned immigrants from the British Isles.
Albinism is a congenital (present at birth) absence of skin pigment. People with this condition may have pink-white skin and white hair. They have a high risk of getting skin cancer unless they are careful to protect their skin.
The risk of basal and squamous cell skin cancers goes up as people get older. Older people have been exposed to the sun for a longer time. Still, these cancers are now being seen in younger people too, probably because they are spending more time in the sun without protecting their skin.
Men are about two times as likely as women to have basal cell cancers and about three times as likely to have squamous cell cancers of the skin. This is thought to be due mainly to higher levels of sun exposure.
Exposure to Certain Chemicals
Exposure to large amounts of arsenic increases the risk of developing skin cancer. Arsenic is a heavy metal found naturally in well water in some areas. It is also used in making some pesticides. Workers exposed to industrial tar, coal, paraffin and certain types of oil may also have an increased risk for non-melanoma skin cancer.
People who have had radiation treatment have a higher risk of developing skin cancer in the area that received the treatment. This is particularly a concern in children who have had radiation treatment for cancer.
Previous Skin Cancer
A person who has already had a non-melanoma skin cancer has a higher risk of getting another one.
Long-term or severe skin inflammation or injury
Scars from severe burns, areas of skin over severe bone infections, and skin damaged by some severe inflammatory skin diseases are more likely to develop keratinocyte skin cancers, although this risk is generally small.
Psoralen and ultraviolet light treatments (PUVA) given to some patients with psoriasis (a long-lasting inflammatory skin disease) can increase the risk of developing squamous cell skin cancer and probably other skin cancers also.
The immune system helps the body fight cancers of the skin and other organs. People with weakened immune systems (due to certain diseases or medical treatments) are more likely to develop non-melanoma skin cancer, particularly squamous cell cancer.
For example, organ transplant patients are usually given medicines that weaken their immune system to prevent their body from rejecting the new organ. This increases their risk of developing skin cancer. The rate of skin cancer in people who have had transplants can be as high as 70 percent within 20 years after the transplant. Skin cancers in people with weakened immune systems tend to grow faster and are more likely to be fatal.
Treatment with large doses of corticosteroid drugs can also depress the immune system. This may also increase a person's risk of skin cancer.
Human papilloma virus (HPV) infection
Human papilloma viruses (HPVs) are a group of more than 100 viruses that can cause papillomas, or warts. The warts that people commonly get on their hands and feet appear to be unrelated to any form of cancer. But some of the HPV types, especially those that people get in their genital and anal area, appear to be related to skin cancers in these areas.
People who smoke are more likely to develop squamous cell skin cancer, especially on the lips. Smoking is not a known risk factor for basal cell cancer.