Though there are multiple risk factors that can contribute to the incidence of skin cancer, doctors now believe that in many cases skin cancers are principally caused by overexposure to ultraviolet (UV) radiation. The most common source of UV radiation is the sun, but UV radiation also comes from tanning beds and sun lamps. UV radiation appears to cause cancer by directly affecting DNA (the genetic material in cells that tells the cells how to grow and reproduce properly). When UV radiation causes a defect in a cell's DNA, that cell can later become cancerous.
For completeness, the factors identified as putting people at increased risk for skin cancer are as follows:
Ultraviolet (UV) Radiation. Skin damage caused by too much unprotected exposure to the sun, tanning booths or sun lamps has been identified as the leading cause of all forms of skin cancer. Whatever the source, the overall amount of UV exposure (and therefore risk) people face is determined by the length of time they remain exposed, the intensity of the radiation they are exposed to, and the amount of protection (e.g., sunscreen, a hat, appropriate clothing) that has been applied to the skin. Do not be fooled into thinking that you are safe from the sun's rays on a cloudy day. UV radiation penetrates clouds easily. Always wear appropriate protection when you go out.
Sun damage is cumulative. Doctors now believe that in some cases of melanoma skin cancer the damage to the skin through UV exposure was done years before the cancer actually showed up.
Skin Tone. Skin pigment provides protection from damaging UV radiation. The darker the pigment in your skin the better that pigment can protect your lower skin tissue layers from UV radiation. As a result, the lighter your skin tone, the greater your risk for getting skin cancers. As an illustration, Caucasian persons may be as much as ten times more likely to get melanoma skin cancer than are persons of African ancestry. Skin pigment conditions such as albinism (absence of skin pigment from birth) can also increase a person's risk for the disease.
Gender. Men are more likely to get skin cancers than are women. The reasons for why this is not fully understood.
Previous Skin Cancer. Anyone who has previously had skin cancer has a heightened risk for getting another skin cancer in the future.
Immune System Suppression. Your immune system helps your body fight off cancer as well as other diseases and infections. People with weakened immune systems have a higher risk for developing skin cancer than people who have a strong and healthy immune system, and also commonly are at increased risk for the rapid spread of those cancers. Immune system weakness can be the result of a disease process (such as HIV/AIDS), or it can be induced by doctors when it is advantageous for other reasons (e.g., to prevent the rejection of transplanted organs, or to slow the progress of autoimmune disorders).
Xeroderma Pigmentosum. Xeroderma pigmentosum is an inherited disease that affects the body's ability to repair damaged skin cell DNA. Individuals with xeroderma pigmentosum have a higher risk for getting skin cancer than people who do not have the disease. People with xeroderma pigmentosum need to be especially careful about exposure to UV radiation.
The following list describes risk factors specific to melanoma skin cancers:
Moles. Moles are not present at birth and usually develop during childhood or adolescence. Regular moles are essentially benign (non-cancerous) tumors, and are not cause for concern. However, some mole subtypes do increase melanoma risk. Dyplastic nevus moles look similar to normal moles except that they are larger. They run in families, and commonly appear in areas exposed to the sun and/or around the groin and upper thighs. Congenital melanocytic nevus moles are observed at birth and similarly increase melanoma cancer risk. Moles can start out normal and then become cancerous. It is important to monitor moles for change in shape, change in color, or irregular borders, and to have any irregularities you discover checked by a physician.
Family Background. Persons with close blood relatives who have developed melanoma skin cancer are themselves at increased risk for developing the same. The increased risk may be due to a genetic vulnerability that is passed down in families.
Age. While melanoma skin cancer is the most common form of skin cancer at any age, a person's risk for developing melanoma increases as they age.
The following list describes risk factors specific to non-melanoma skin cancers:
Exposure to non-UV Radiation. While UV radiation increases skin cancer risk across the board, people exposed to other forms of radiation (such as therapeutic radiation), are at heightened risk for developing non-melanoma skin cancers. Patients who have had radiation therapy should get into the habit of periodically monitoring the skin around their treatment sites to check for skin cancers.
Basal Cell Nevus Syndrome. Basal cell nevus syndrome is a rare, genetically inherited disease that increases risk of non-melanoma skin cancer and does so at early ages, including in individuals younger than twenty years of age.
Chemical Exposure. People who are routinely exposed to industrial chemicals like arsenic, coal, tar, and certain oils have a greater risk for getting non-melanoma skin cancer than individuals who are not regularly exposed to these chemicals.
Smoking. People who smoke are more likely to develop squamous cell carcinomas compared with nonsmokers.
Permanent Skin Injury. Permanent skin injuries such as burns and scars pose a small increase in risk for non-melanoma skin cancer developing at the site of injury.
The best way to prevent both melanoma and non-melanoma forms of skin cancer is to limit the number one risk factor for the diseases: UV exposure. The easiest forms of UV exposure you can cut out of your life are tanning beds and sun lamps. If you do not feel as though you can totally eliminate these forms of UV light from your life, then you at least have the option to use them very sparingly. Without question, the healthiest option is to not use tanning beds and sun lamps at all.
The largest single source of UV radiation is sunlight. Doctors suggest that precautionary measures be taken to protect the skin from UV rays before going outside. These precautions are warranted even on overcast days! Here are some guidelines for practicing proper sun safety:
Wear Sunscreen. Daily application of sunscreen is an important way to help protect your skin from the sun's rays. Sunscreen is a good idea whether or not the sun is shining. Sunscreens are rated with an SPF factor, which indicates the level of protection each product offers. Higher SPF numbers offer more protection. If possible, you should strive to use sunscreen products offering SPF 15 or higher (with SPF 30 or 45 an even better option). You should also look for a sunscreen product offering complete UVA and UVB radiation protection (as these forms of UV radiation are the most dangerous). Whatever sunscreen product you choose, read the application instruction on your sunscreen product and follow them. Sunscreen should be applied generously to areas of skin which will be exposed to the sun. Sunscreen often will not be effective until 30 minutes after it is applied so you should anticipate putting it on before you go outside, not when you get to the beach. Sunscreen will need to be reapplied every two hours or so to ensure maximum protection throughout the day. Remember that your lips can also burn. Find a lip balm with sunscreen to protect your lips. Please note that though sunscreens are useful for lessening your risk of exposure to UV rays, they do not completely eliminate your chances of sun damage and skin cancer.
Wear Protective Clothing and a Hat. Clothing acts as a barrier between your skin and harmful UV rays. As a general rule, thicker fabrics with tighter weaves and dark colors will better protect you from UV radiation. Long sleeve shirts and long pants are best choices whenever possible and practical.
A hat can provide a vital protection for your scalp, even if you have a full head of hair! Many people mistakenly believe that hair protects your head from the sun's rays, but this is not the case. Hats with wide brims or bills work best because they also provide protection to the neck, nose and ears.
Find Shade. If you are going to be outside for a long period of time you should try to spend as much of that time as possible in a shady area. A tree or an umbrella can provide protection from UV radiation in much the same way that clothing can. It is especially important to be protected from the sun during the hours of 10 am to 4 pm when UV radiation is at its highest intensity.
Wear Sunglasses. It is possible to get some forms of skin cancer inside your eyes. You can help protect your eyes by wearing sunglasses that provide 99% protection from UVA and UVB rays.