Basal cell carcinoma (BCC) is the most common skin cancer, and its risk factors span a wide range, from sun exposure patterns and skin type to genetics, medications, and environmental toxins. Some of these you can control, others you can’t, but understanding them helps you gauge your personal risk and take practical steps to reduce it.
UV Exposure: Pattern Matters More Than Total Amount
Ultraviolet radiation is the single biggest driver of basal cell carcinoma, but the way you get that UV exposure matters. Intense, intermittent sun exposure, the kind you get on beach vacations or weekend outdoor activities, raises BCC risk more than steady, cumulative exposure from daily outdoor work. This is a counterintuitive finding, since you might assume that someone who works outdoors for decades would be at greatest risk. They do face higher rates of squamous cell carcinoma, but for BCC specifically, it’s the pattern of burning and recovering that does the most damage.
Childhood and adolescent sun exposure is especially important. Population-based research shows that recreational sun exposure during these early life stages significantly increases BCC risk later in life. A bad sunburn at age 12 can set the stage for a skin cancer diagnosis decades later, because UV damage to skin cell DNA accumulates over a lifetime and the repair mechanisms established early on shape long-term vulnerability.
Where you live also plays a role. An 18-year study following nearly 85,000 U.S. nurses found that living in high-UV-index regions, or at higher altitudes where UV intensity is greater, increased the risk of BCC. This applied not just to where participants currently lived, but where they had lived at age 15 and 30, reinforcing the idea that UV exposure history across your whole life contributes to risk.
Fair Skin and Light Features
People with lighter skin that burns easily and tans poorly (classified as Fitzpatrick skin types I and II) have roughly twice the risk of developing BCC compared to those with darker skin types. If you have red or blond hair, light-colored eyes, and a tendency to freckle, you fall into this higher-risk category. Darker skin produces more melanin, which acts as a natural, partial shield against UV damage. BCC can still occur in people with darker skin, but it is far less common.
Age, Gender, and Personal History
BCC becomes increasingly common with age. The average age at diagnosis is around 66, and the largest group of cases falls between ages 70 and 75. This reflects the decades it takes for accumulated DNA damage to produce a tumor. That said, BCC can appear much earlier, particularly in people with strong risk factors like a genetic syndrome or heavy tanning bed use.
Historically, men were diagnosed with BCC at roughly twice the rate of women, likely due to greater occupational sun exposure. More recent data shows that gap narrowing, and some populations now show a slight female predominance, possibly driven by changes in recreational sun habits and tanning bed use among women.
One of the strongest predictors of a new BCC is having already had one. If you’ve been diagnosed with a nonmelanoma skin cancer, your estimated risk of developing another is 35% within three years and 50% within five years. This makes regular follow-up skin checks essential after a first diagnosis.
Genetic Conditions That Dramatically Raise Risk
A rare inherited condition called Gorlin syndrome (also known as basal cell nevus syndrome) causes people to develop numerous BCCs starting at a young age. The median age for a first BCC in Gorlin syndrome is just 20 years old, and some patients develop tumors in infancy. These cancers can look like classic pearly, translucent bumps or may resemble harmless skin tags, making them easy to miss without close monitoring.
Gorlin syndrome is caused by a mutation in the PTCH1 gene and follows an autosomal dominant pattern, meaning a child has a 50% chance of inheriting it from an affected parent. Beyond skin cancer, it causes a constellation of other features: cysts in the jaw, small pits on the palms and soles, skeletal abnormalities, and sometimes childhood brain tumors. A diagnosis typically requires at least two of these major features, or one major feature plus two minor ones. If you have a family history of very early or unusually frequent BCCs, this syndrome is worth discussing with a dermatologist or geneticist.
Immunosuppression
A weakened immune system substantially increases the risk of skin cancer. Organ transplant recipients, who take immunosuppressive medications to prevent rejection, develop BCC at roughly 10 times the rate of the general population. The type of immunosuppressive drug, the dose, and the duration of treatment all influence how much the risk climbs.
Interestingly, transplant recipients experience an inversion of the usual skin cancer ratio. In the general population, BCC is far more common than squamous cell carcinoma (SCC). In transplant patients, SCC becomes more common, with incidence rates 65 to 250 times higher than normal. BCC still rises dramatically, but SCC overtakes it. Other conditions that suppress immune function, including HIV and certain blood cancers, also raise skin cancer risk.
Prior Radiation Therapy
If you’ve received radiation therapy to any part of your body, that area carries a higher risk of BCC in the years and decades that follow. The risk is concentrated at the site of radiation exposure, where one study found a 3.3-fold increase in BCC odds. People treated with radiation for acne, a now-abandoned practice, had among the highest risks. Earlier research on patients treated with radiation for scalp ringworm found five- to six-fold increases in head and neck BCC.
The latency period is long. BCC risk begins climbing within 20 years of radiation treatment and is highest 40 or more years afterward. This means someone who received chest radiation for lymphoma in their 20s should still be vigilant about skin checks on that area in their 60s and beyond.
Arsenic Exposure
Chronic exposure to inorganic arsenic is a well-established but often overlooked BCC risk factor. The main routes are contaminated drinking water and food, though inhalation in industrial or agricultural settings also contributes. A large Taiwanese cohort study found a three- to four-fold increase in BCC incidence in regions where arsenic-contaminated groundwater was common, compared to areas without contamination.
Arsenic-related BCC risk is most relevant in parts of the world where groundwater naturally contains high arsenic levels, including regions of Bangladesh, Taiwan, Chile, and parts of the western United States. If you rely on a private well in an area with known arsenic contamination, testing your water is a straightforward precaution.
Photosensitizing Medications
Certain medications make your skin more sensitive to UV damage, which can amplify BCC risk over time. Tetracycline antibiotics, commonly prescribed for acne and other infections, have been linked to an increased risk of BCC in population-based research. If you take a medication that carries a photosensitivity warning, you’re effectively getting a larger dose of UV damage from the same amount of sun exposure. Wearing sunscreen and protective clothing becomes more important while on these drugs, especially during prolonged courses.