Causes and Risk Factors for Basal Cell Carcinoma

Basal cell carcinoma (BCC) develops when DNA damage causes abnormal growth in skin cells, most often due to exposure to ultraviolet (UV) radiation from the sun or indoor tanning devices. It is the most common type of skin cancer and the most frequently diagnosed cancer overall in the United States, with an estimated 3.6 million new cases reported each year.

BCC can affect anyone, but older adults and individuals with fair skin, frequent sun exposure or certain genetic traits are at higher risk. While the cancer rarely spreads to distant parts of the body, it can continue to grow and damage nearby skin, tissues and structures if left untreated. For this reason, early diagnosis and prompt treatment are important.

What causes basal cell carcinoma?

BCC occurs when basal cells in the outermost layer of the skin undergo genetic changes that cause them to grow and divide uncontrollably, forming a cancerous tumor. In most cases, these DNA mutations are linked to cumulative exposure to UV radiation from the sun or indoor tanning devices. However, not all cases of basal cell carcinoma can be traced to a specific cause, and researchers continue to study the complex interplay of factors involved in its development.

Common causes of BCC include:

• Ultraviolet radiation exposure – UV rays from the sun and indoor tanning devices can damage the DNA in skin cells over time. Tanning beds, standup booths, canopies and sunlamps emit UV radiation that can cause the same type of skin damage as natural sunlight. Repeated exposure is the primary cause of the genetic changes that lead to basal cell carcinoma.
• DNA mutations affecting cell growth – Changes in the genes that regulate skin cell growth and repair can cause basal cells to multiply uncontrollably. These mutations are often linked to UV damage but may also occur for other reasons.
• Ionizing radiation exposure – Previous radiation therapy and exposure to other forms of ionizing radiation can damage cellular DNA and contribute to the development of basal cell carcinoma, sometimes years after the exposure occurs.

What are the risk factors for basal cell carcinoma? 

While UV exposure is the primary cause of BCC, several other factors may increase the risk. Some can be influenced by lifestyle choices, while others cannot.

Risk factors for basal cell carcinoma include:

• Frequent or prolonged sun exposure – Spending significant time outdoors, especially without adequate sun protection, can increase cumulative UV damage and raise the risk of basal cell carcinoma.
• History of sunburns – One or more severe or blistering sunburns, particularly during childhood or adolescence, can contribute to long-term skin damage that increases the risk of skin cancer.
• Indoor tanning – Use of tanning devices may increase an individual’s lifetime exposure to UV radiation.
• Fair skin, light eyes or light-colored hair – Individuals with these traits typically have lower levels of melanin, a pigment that helps protect the skin from UV damage. As a result, they are at increased risk of developing basal cell carcinoma.
• Older age – The risk of skin cancer increases with age as UV-related skin damage accumulates over time, although basal cell carcinoma can occur at any age.
• Personal history of skin cancer – Individuals who have previously had basal cell carcinoma or another type of skin cancer are more likely to develop additional skin cancers in the future.
• Family history of skin cancer – Having a close relative with basal cell carcinoma or another type of skin cancer may increase an individual’s risk due to shared genetic or environmental factors.
• Weakened immune system – Individuals who have undergone organ transplantation, take immunosuppressive medications or have certain medical conditions, such as HIV/AIDS, leukemia or lymphoma, may have a higher risk of developing skin cancer.
• Certain inherited syndromes – Rare genetic disorders, such as basal cell nevus syndrome (Gorlin syndrome) and xeroderma pigmentosum, can impair the body’s ability to repair damaged DNA, increasing the risk of basal cell carcinoma.

Which risk factors for basal cell carcinoma are modifiable (factors you can control?

Some risk factors for BCC can be reduced through lifestyle changes and preventive measures. Taking steps to address these factors may help lower the risk.

Modifiable risk factors for basal cell carcinoma include:

• Excessive sun exposure – Reducing time spent in direct sunlight, especially during peak UV hours, can help limit ongoing skin damage and lower skin cancer risk.
• Inadequate sun protection – Consistently using broad-spectrum sunscreen, wearing protective clothing and seeking shade when appropriate can help protect the skin from harmful UV radiation.
• Indoor tanning – Avoiding tanning devices can eliminate a preventable source of UV exposure.

Which risk factors for basal cell carcinoma are nonmodifiable (factors you cannot change)?

Although certain risk factors for BCC cannot be changed, recognizing them may help identify individuals who could benefit from increased skin cancer awareness, regular skin examinations and closer monitoring.

Nonmodifiable risk factors for basal cell carcinoma include:

• Older age – Because skin damage accumulates over a lifetime, the likelihood of developing basal cell carcinoma generally increases as people get older.
• Fair skin – Individuals who naturally burn more easily than they tan may have less inherent protection against UV-related skin damage.
• Light-colored eyes or hair – Blue, green or gray eyes and blonde or red hair are often associated with lower levels of melanin, which may increase susceptibility to UV damage.
• Personal history of skin cancer – A previous skin cancer diagnosis may indicate an underlying predisposition to developing additional skin cancers.
• Family history of skin cancer – A family history of BCC may suggest inherited traits that increase vulnerability to skin cancer.
• Certain inherited genetic syndromes – Rare conditions such as basal cell nevus syndrome (Gorlin syndrome) and xeroderma pigmentosum can significantly impair the body’s ability to control abnormal cell growth or repair DNA damage.
• Weakened immune system – Some medical conditions and long-term treatments that affect immune function may make it harder for the body to identify and eliminate abnormal cells before they become cancerous.

Can basal cell carcinoma be prevented?

Although not every case of basal cell carcinoma can be prevented, many BCCs are linked to UV exposure and may be avoidable through consistent sun protection and early detection of unusual skin changes.

Strategies that may help prevent basal cell carcinoma include:

• Use sunscreen daily – Apply a broad-spectrum, water-resistant sunscreen with an SPF of 30 or higher to exposed skin and reapply as directed, especially after swimming or sweating.
• Avoid indoor tanning – Choosing not to use tanning beds, booths and sunlamps can help reduce skin cancer risk.
• Seek shade during peak sunlight hours – UV rays are typically strongest between 10 a.m. and 4 p.m., making shade an important protective measure when spending time outdoors.
• Wear UV-protective clothing and accessories – Long-sleeved shirts, long pants, wide-brimmed hats and sunglasses can help shield the skin from UV exposure.
• Perform regular skin self-examinations – Checking the skin for new, changing or unusual lesions may help identify potential concerns early.
• Schedule routine skin examinations when appropriate – Individuals at increased risk for skin cancer may benefit from periodic evaluations by a dermatologist or another skin cancer specialist.

Find the help you need for basal cell carcinoma at Moffitt Cancer Center

Understanding the causes and risk factors for basal cell carcinoma can help you take steps to protect your skin and recognize potential concerns early.

If you would like to learn more about basal cell carcinoma treatment, you can request an appointment with a specialist in our Cutaneous Oncology Program by calling 1-888-663-3488 or submitting a new patient registration form online. We do not require referrals.