A risk factor  is anything that increases a person's chance of developing cancer. Although risk factors can influence the development of cancer, most do not directly cause cancer. Some people with several risk factors never develop cancer, while others with no known risk factors do. However, knowing your risk factors and talking about them with your doctor may help you make more informed lifestyle and health care choices.
The following factors may raise a person's risk of developing skin cancer:
Exposure to sunlight/UV radiation. Ultraviolet B (UVB) radiation causes sunburn and plays a role in the development of basal and squamous cell cancers. Ultraviolet A (UVA) penetrates the skin more deeply and contributes to photoaging (premature aging of the skin) or wrinkling. The role of UVA in the development of non-melanoma skin cancer is suspected, but not yet certain. People who live in areas with year-round, bright sunlight (which includes both UVA and UVB) or at high altitudes have a higher risk of developing skin cancer, as do those who spend significant time outside or on a tanning bed (which emits mostly UVA).
Fair skin. Less pigment (melanin) in skin offers poorer protection against UV radiation. People with light hair and light-colored eyes who have skin that tans poorly or freckles, or those who burn easily, are more likely to develop skin cancer.
Gender. Rates of skin cancer in older white men and younger women have increased in recent years.
Age. Most basal cell and squamous cell cancers typically appear after age 50, but cancers may appear earlier in individuals with sun-damaged skin. In recent years, the number of skin cancers in people age 65 and older has increased dramatically.
A history of sunburns or fragile skin. Skin that has been burned, sunburned, or injured from disease has a higher risk of skin cancer. Squamous cell and basal cell cancers occur more often in people with higher lifetime exposure to the sun or other sources of UV radiation.
Individual history. People with weakened immune systems or those who use certain medications (such as immunosuppressive drugs, certain steroids, and drugs that make the skin sensitive to light) have a higher risk of developing skin cancer, particularly squamous cell cancer. People with some rare genetic conditions, such as xeroderma pigmentosum , nevoid basal cell carcinoma syndrome , or albinism have a much higher risk of developing skin cancer.
Previous skin cancer. People who have had any form of skin cancer have a higher risk of developing another skin cancer. Thirty-five percent (35%) to 50% of people diagnosed with one basal cell cancer will develop a new skin cancer within five years. Therefore, people who have had one skin cancer need ongoing, follow-up care to watch for additional cancers.
Precancerous skin conditions. Lesions called actinic keratoses (rough, red or brown scaly patches on the skin) or Bowen's disease are usually more common in areas exposed to the sun. Such areas can change into squamous cell cancers in some people. Bowen's disease in non-sun-exposed areas may be related to arsenic exposure. Use of sunscreens may decrease the risk of actinic keratoses.
Human papillomavirus (HPV). Research indicates that infection with this virus is a risk factor for squamous cell carcinoma, particularly if the person's immune system becomes suppressed. HPV is most commonly passed from person to person during sexual activity. There are different types, or strains, of HPV, and some strains are more strongly associated with certain types of cancers. Learn more about HPV and cancer .
Reducing exposure to sunlight and other sources of UV radiation lowers the risk of skin cancer. This is important for all age groups, but is especially important for people who have risk factors for skin cancer. Sun damage is cumulative, meaning it builds up over time. Steps to reduce sunlight exposure and help prevent skin cancer include:
- Preventing sunburn
- Limiting or avoiding sun exposure between 10:00 AM and 4:00 PM
- Wearing sun-protective clothing and a hat that shades the face, neck, and ears. Clothes made of fabric labeled with UPF (UV protection factor) may provide better protection. UV-protective sunglasses are also recommended.
- Using sunscreen with a sun protection factor (SPF) of 15 or higher throughout the year and reapplying it at least every two hours, especially after heavy perspiration or being in the water
- Avoiding use of sun lamps, tanning beds, or tanning salons
- Examining skin regularly (examinations by a health care professional and self-examinations). Learn more about the signs and symptoms  of non-melanoma skin cancer.
Learn more about protecting your skin from the sun .
It is important to note that limiting your sun exposure reduces your body's production of vitamin D. Therefore, people with limited sun exposure should talk with their doctor about how to include good sources of vitamin D in their diet, including the use of supplements.