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Basal and Squamous Cell Skin Cancer
A risk factor is anything that raises your risk of getting a disease such as cancer. Different cancers have different risk factors. Some risk factors, like smoking and excess sun exposure, can be changed. Others, like your age or family history, can’t be changed.
Having a risk factor, or even many risk factors, does not mean that you will get skin cancer. Many people with risk factors for skin cancer never get it. And some people who do get it may have few or no known risk factors.
Still, it’s important to know about the risk factors for skin cancer because there may be things you can do that could lower your risk of getting it. If you are at higher risk because of certain factors, there are also things you can do that might help find it early, when it’s likely to be easier to treat.
Several risk factors make a person more likely to get basal cell or squamous cell skin cancer.
Exposure to ultraviolet (UV) rays 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.
While UV rays make up only a very small portion of the sun’s rays, they are the main cause of the damaging effects of the sun on the skin. UV rays damage the DNA (genes) inside skin cells. Skin cancers can begin when this damage affects the DNA of genes that control skin cell growth.
To learn more about UV exposure and what you can do to protect yourself and your loved ones, see How Do I Protect Myself from Ultraviolet (UV) Rays?
Anyone can get skin cancer, but people with light-colored skin have a much higher risk than people with naturally darker skin color. This is because the skin pigment melanin has a protective effect in people with darker skin. White people with fair (light-colored) skin that freckles or burns easily, blue or green eyes, and naturally red or blonde hair are at especially high risk.
Albinism is an inherited lack of protective skin pigment. People with this condition may have pink-white skin and white hair. They have a very high risk of getting sunburns and skin cancer, so they need to be careful to protect their skin.
The risk of getting basal and squamous cell skin cancers rises as people get older. This is probably because of the buildup of sun exposure over time. But these cancers are becoming more common in younger people as well, probably because they are spending more time in the sun with their skin exposed.
Men are more likely than women to get basal and squamous cell cancers of the skin. This is thought to be due mainly to getting more sun exposure.
Being exposed to large amounts of arsenic increases the risk of developing skin cancer. Arsenic is an element found naturally in well water in some areas. It’s also used in making some pesticides and in some other industries.
Workers exposed to coal tar, paraffin, and certain types of petroleum products may also have an increased risk of 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.
People who have had a basal or squamous cell cancer have a much higher chance of developing another one.
Scars from severe burns, areas of skin over serious bone infections, and skin damaged by some severe inflammatory skin diseases are more likely to develop skin cancers, although this risk is generally small.
Psoralens and ultraviolet light (PUVA) treatments given to some patients with psoriasis (a chronic inflammatory skin disease) can increase the risk of developing squamous cell skin cancer and probably other skin cancers.
This very rare inherited condition reduces the ability of skin cells to repair DNA damage caused by sun exposure. People with this disorder often develop many skin cancers, starting in childhood.
In this rare congenital (present at birth) condition, people develop many basal cell cancers over their lifetime. People with this syndrome may also have abnormalities of the jaw (and other bones), eyes, and nervous tissue.
Most of the time this condition is inherited from a parent. In families with this syndrome, those affected often start to develop basal cell cancers as children or teens. Exposure to UV rays can increase the number of tumors these people get.
The immune system helps the body fight cancers of the skin and other organs. People with weakened immune systems (from certain diseases or medical treatments) are more likely to develop many types of skin cancer, including squamous cell cancer, melanoma, and less common types such as Kaposi sarcoma and Merkel cell carcinoma.
For example, people who get organ transplants are usually given medicines that weaken their immune system to help prevent their body from rejecting the new organ. This increases their risk of developing skin cancer. 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 weaken the immune system. This may also increase a person’s risk of skin cancer.
People infected with HIV, the virus that causes AIDS, often have weakened immune systems and also are at increased risk for basal and squamous cell cancers.
Human papillomaviruses (HPVs) are a group of more than 150 viruses, many of which can cause papillomas, or warts. The warts that people commonly get on their hands and feet are not related to any form of cancer. But some HPV types, especially those that affect the genital and anal areas and the skin around the fingernails, seem 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.
The American Cancer Society medical and editorial content team
Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.
Christensen SR, Wilson LD, Leffell DJ. Chapter 90: Cancer of the Skin. In: DeVita VT, Lawrence TS, Rosenberg SA, eds. DeVita, Hellman, and Rosenberg’s Cancer: Principles and Practice of Oncology. 11th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2019.
National Cancer Institute. Genetics of Skin Cancer (PDQ®)–Health Professional Version. 2019. Accessed at https://www.cancer.gov/types/skin/hp/skin-genetics-pdq on May 31, 2019.
Silverberg MJ, Leyden W, Warton EM, et al. HIV infection status, immunodeficiency, and the incidence of non-melanoma skin cancer. J Natl Cancer Inst. 2013;105:350-360.
Xu YG, Aylward JL, Swanson AM, et al. Chapter 67: Nonmelanoma Skin Cancers. In: Niederhuber JE, Armitage JO, Doroshow JH, Kastan MB, Tepper JE, eds. Abeloff’s Clinical Oncology. 6th ed. Philadelphia, Pa: Elsevier; 2020.
Last Revised: July 26, 2019
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