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Skin cancer types: Basal cell carcinoma causes

What causes basal cell carcinoma?

The cause of basal cell carcinoma, 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

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

Use a tanning bed just once, and you increase your risk of developing basal cell carcinoma by 29%.

Young woman using a tanning bed

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 (or BCC) 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 BCC, which include:

  • Color of your skin, hair, and eyes. This skin cancer develops in skin damaged by UV light, and skin is more easily damaged by UV light if you have 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.

  • Where you live. 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.

  • 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, BCC 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 greatly.

  • Some medical conditions. If you have one of the following medical conditions, you have an increased risk of developing BCC. Some people who have one of these conditions develop 100's 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 BCC 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 BCC.

  • 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 BCC.

While having a risk factor for BCC 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 the skin that is growing, bleeding, or changing in any way should see a board-certified dermatologist to find out what it is. You’ll find out how this cancer is diagnosed and treated at, Basal cell carcinoma: Diagnosis and treatment.

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.

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