Skin Cancer: Basal and Squamous Cell Overview

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Causes, Risk Factors, and Prevention TOPICS

What are the risk factors for basal and squamous cell skin cancers?

A risk factor is anything that affects a person’s chance of getting a disease such as cancer. Different cancers have different risk factors. Some risk factors, like smoking, can be changed. Others, like a person’s age or family history, can’t be changed.

But having a risk factor, or even several, does not mean that you will get the disease. And some people who get the disease may have had few or no known risk factors. Even if a person with basal or squamous cell skin cancer has a risk factor, it is often very hard to know what part that risk factor may have played in getting the cancer.

Risk factors for basal and squamous cell skin cancer

Ultraviolet (UV) light

Ultraviolet (UV) light is thought to be the major risk factor for most skin cancers. Sunlight is the main source of UV rays. Tanning beds are another source of UV rays. People who get a lot of exposure to UV light are at greater risk for skin cancer.

There are different types of UV rays, but they can all damage skin and cause skin cancer. There are no safe UV rays.

The amount of UV exposure depends on the strength of the light, how long the skin is exposed, and whether the skin was covered with clothing or sunscreen. Many studies show that being exposed to a lot of sun when you are young is an added risk factor.

People who live in places with year-round, bright sunlight have a higher risk. For example, the risk of skin cancer is twice as high in Arizona compared to Minnesota. Spending a lot of time outdoors without covering your skin and using sunscreen increases your risk.

Light-colored skin

The risk of skin cancer is much higher for whites than for African Americans or Hispanics. This is because the skin pigment melanin helps protect against UV rays. People with darker skin have more melanin. People with fair (light-colored) skin that freckles or burns easily are at extra high risk.

Older age

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, most likely because they are spending more time in the sun without protecting their skin.

Male gender

Men are about twice as likely as women to have basal cell cancers and about 3 times as likely to have squamous cell cancers of the skin. This could be because they tend to spend more time in the sun.


Exposure to large amounts of arsenic increases the risk of skin cancer. Arsenic is a heavy metal used to make some pesticides and other products. It is also a natural part of well water in some areas.

Workers exposed to coal tar, paraffin, and certain types of oil may have an increased risk, too.


People who have had radiation treatment have a higher risk of getting skin cancer in the area that was treated. This can be a concern in children who have had cancer treatment.

Having had a skin cancer

Anyone who has had a basal or squamous cell cancer has a much higher chance of having another one.

Certain long-term or severe skin problems

Scars from bad burns, areas of skin over bad bone infections, and skin damaged by certain skin diseases are more likely to develop skin cancer, but this risk is fairly small.

Psoriasis treatment

Some patients with psoriasis (a long-lasting inflammatory skin disease) are treated with psoralens and ultraviolet light treatments (PUVA). This can increase their risk of getting squamous cell skin cancer, and maybe other skin cancers, too.

Certain diseases

Xeroderma pigmentosum (XP): This very rare disease makes the skin less able to repair sun damage. This disease tends to run in families. People with this disease get many skin cancers, often starting in childhood.

Basal cell nevus syndrome (Gorlin syndrome): This rare condition is present at birth and often runs in families. It causes some people to start having many basal cell cancers as children or teens. Exposure to UV rays can increase the number of tumors these people get.

Weakened immune system

People with weak immune systems are more likely to develop some types of skin cancer. For instance, people who have had an organ transplant often take medicines to weaken the immune system so that the body will not reject the organ. And people infected with HIV, the virus that causes AIDS, often have weakened immune systems. These people are more likely to develop skin cancer. Skin cancers in people with weak immune systems tend to grow faster and are more likely to be fatal.

HPV infection

A small number of skin cancers seem to be linked to infection with human papilloma virus (HPV), which can cause warts. The warts that people most often get on their hands and feet are not linked to any form of cancer. But some types of HPV can cause changes in the skin cells in the genital and anal areas and around the fingernails. They seem to be linked to skin cancers in these areas.


Smoking is a risk factor for squamous cell skin cancer, but it is not a known risk for basal cell cancer.

Last Medical Review: 02/24/2014
Last Revised: 02/24/2014