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Skin cancer types: Basal cell carcinoma causes

What causes basal cell carcinoma?

The cause of basal cell carcinoma (BCC), the most common type of skin cancer, is well known. Most people develop it because their skin has been badly damaged by ultraviolet (UV) light from:

  • The sun

  • Indoor tanning equipment (such as tanning beds or sunlamps)

  • Both the sun and indoor tanning

People who have lighter skin tones have a higher risk of developing UV-damaged skin.

If you use a tanning bed, you have a higher risk of developing skin cancer

Indoor tanning can increase your risk of developing basal cell carcinoma by 24%¹.

Woman lying in tanning bed, which increases her risk of developing basal cell carcinoma

How can UV light cause skin cancer?

Every time UV light hits our skin, it can damage some of the DNA inside our skin’s cells. The body tries to repair this damage.

As UV light from the sun, indoor tanning equipment, or both, continues to hit our skin, the damage builds up. Eventually, it becomes too much for the body to repair. When the body cannot repair the damage, changes called mutations develop. When the mutations build up in the skin, we get skin cancer.

The type of skin cancer we get depends on where the mutations develop in the skin. Basal cells are found deep inside the first layer of our skin, so we get basal cell carcinoma when mutations develop inside these cells.

Do some people have a higher risk of getting basal cell carcinoma?

Yes. The main risk factor (anything that increases your risk of getting a disease) for getting this skin cancer is:

  • UV-damaged skin, caused by the sun or tanning beds: Each time you go outdoors without protecting your skin from the sun or use a tanning bed, you increase your risk of getting skin cancer.

There are other risk factors for basal cell carcinoma, which include:

  • Lighter skin tone: This skin cancer develops in skin damaged by UV light, and skin is more easily damaged by UV light if you have a light skin tone and one or more of the following:

    • Skin that burns easily and rarely tans
    • Sun-sensitive skin that freckles easily
    • Naturally blonde or red hair
    • Blue or green eyes

  • Sunburns: If you’ve had sunburns, especially blistering ones in your youth, you have a higher risk of developing this skin cancer.

  • Live in an area with intense sunlight or the mountains: Living in an area that gets intense sunlight year-round, such as Florida or California, increases your risk of getting skin cancer. People who live at a high altitude also have an increased risk.

  • Your work: People in certain occupations have a higher risk of developing this skin cancer. For example, studies have found that people who work outdoors have an increased risk when compared to people who work indoors. If you work in one of the following occupations, you may have a higher risk of developing basal cell carcinoma:

    • Asphalter
    • Farmer, park ranger, and other outdoor worker
    • Roofer
    • Military service (veterans and active duty)
    • Pilot or flight crew
    • Welder (metal arc)

  • Previous skin cancer: If you’ve had any type of skin cancer, you have a greater risk of getting another one.

  • Weakened immune system: Anything that weakens your immune system increases your risk of getting this skin cancer. In fact, basal cell carcinoma is one of the cancers most likely to develop when the immune system weakens.

    If you received an organ transplant, the medication you take to prevent your body from rejecting the organ suppresses your immune system. This increases your risk of developing basal cell skin cancer.

  • Some medical conditions: If you have one of the following medical conditions, you have an increased risk of developing basal cell carcinoma. Some people who have one of these conditions develop hundreds of skin cancers.

    • Nevoid basal cell carcinoma syndrome (aka Gorlin syndrome)
    • Xeroderma pigmentosum
    • Rombo syndrome
    • Bazex-Dupre-Christol syndrome

  • 100+ PUVA sessions: Used to treat psoriasis and some other conditions that affect the skin, this therapy involves taking a medication called psoralen, which makes your skin more sensitive to UV light. After the medication takes effect, the skin that needs treatment is exposed to controlled UV light.

    Research indicates that your risk of developing basal cell carcinoma increases if you’ve had 100 or more PUVA treatments.

  • X-ray treatments for acne: While no longer used to treat acne, some people received these treatments in their youth.

  • Dialysis for kidney disease: People who are receiving dialysis have a much greater risk of developing basal cell carcinoma.

  • Arsenic in your food or water: Many researchers have found that the more arsenic found in your food or water, the greater your risk of developing basal cell carcinoma.

While having a risk factor for basal cell carcinoma increases your risk of developing it, some people who get this skin cancer don’t have risk factors. People of all colors get this skin cancer, including people of African, Asian, and Latin descent.

Anyone who finds a spot on their skin that is growing, bleeding, or changing in any way should see a board-certified dermatologist. No one knows your skin better than a board-certified dermatologist.

To find out how dermatologists diagnose and treat this cancer, go to Basal cell carcinoma: Diagnosis and treatment.

1American Academy of Dermatology. “Indoor tanning fact sheet.” Last updated 6/21/22. Last accessed 4/11/2023.

Getty Images

American Academy of Dermatology. Media Fact Sheet: Indoor Tanning. Last accessed February 8, 2019.

Bichakjian CK, Armstrong A, et al. “Guidelines of care for the management of basal cell carcinoma.” J Am Acad Dermatol 2018;78:540-59.

Bichakjian CK, Olencki T, et al. “Basal cell skin cancer, Version 1.2016, NCCN Clinical Practice Guidelines in Oncology.” J Natl Compr Canc Netw. 2016;14(5):574-97.

Cameron MC, Lee E, et al. “Basal cell carcinoma: Epidemiology; pathophysiology; clinical and histological subtypes; and disease associations.” J Am Acad Dermatol 2019;80:303-17.

Ferrucci LM, Cartmel B, et al. “Indoor tanning and risk of early-onset basal cell carcinoma.” J Am Acad Dermatol 2012;67:552-62.

Heltoft, K.N., Slagor, R.M., Agner, T. et al. “Metal arc welding and the risk of skin cancer.” Int Arch Occup Environ Health 90, 873-81.

Margosian E. “Occupational associations of skin cancer.” Dermatol World. 2023;33(3):26-32.

Nouri K, Ballard CJ, et al. “Basal cell carcinoma.” In: Nouri K, et al. Skin Cancer. McGraw Hill Medical, China, 2008: 61-81.

Schmitt J, Haufe E, et al. “Occupational UV-exposure is a major risk factor for basal cell carcinoma: Results of the population-based case-control study FB-181.” J Occup Environ Med. 2018 Jan;60(1):36-43.

Written by:
Paula Ludmann, MS

Reviewed by:
Carrie L. Kovarik, MD, FAAD
Natalie H. Matthews, MD, FAAD
Darrell S. Rigel, MD, FAAD

Last updated: 4/28/23