user: How to prevent Skin Cancer ?

assistant: Key Points
                    - Avoiding risk factors and increasing protective factors may help prevent cancer.    - Being exposed to ultraviolet radiation is a risk factor for skin cancer.    - It is not known if the following lower the risk of nonmelanoma skin cancer:         - Sunscreen use and avoiding sun exposure     - Chemopreventive agents        - It is not known if the following lower the risk of melanoma:         - Sunscreen     - Counseling and protecting the skin from the sun        - Cancer prevention clinical trials are used to study ways to prevent cancer.    -  New ways to prevent skin cancer are being studied in clinical trials.
                
                
                    Avoiding risk factors and increasing protective factors may help prevent cancer.
                    Avoiding cancer risk factors may help prevent certain cancers. Risk factors include smoking, being overweight, and not getting enough exercise. Increasing protective factors such as quitting smoking and exercising may also help prevent some cancers. Talk to your doctor or other health care professional about how you might lower your risk of cancer.
                
                
                    Being exposed to ultraviolet radiation is a risk factor for skin cancer.
                    Some studies suggest that being exposed to ultraviolet (UV) radiation and the sensitivity of a persons skin to UV radiation are risk factors for skin cancer. UV radiation is the name for the invisible rays that are part of the energy that comes from the sun. Sunlamps and tanning beds also give off UV radiation.   Risk factors for nonmelanoma and melanoma cancers are not the same.         -  Risk factors for nonmelanoma skin cancer:                  - Being exposed to natural sunlight or artificial sunlight (such as from tanning beds) over long periods of time.       - Having a fair complexion, which includes the following:                         - Fair skin that freckles and burns easily, does not tan, or tans poorly.         - Blue or green or other light-colored eyes.          - Red or blond hair.                       - Having actinic keratosis.        - Past treatment with radiation.       - Having a weakened immune system.       - Being exposed to arsenic.                -  Risk factors for melanoma skin cancer:                  - Having a fair complexion, which includes the following:                         - Fair skin that freckles and burns easily, does not tan, or tans poorly.          - Blue or green or other light-colored eyes.         - Red or blond hair.                      - Being exposed to natural sunlight or artificial sunlight (such as from tanning beds) over long periods of time.       - Having a history of many blistering sunburns, especially as a child or teenager.       - Having several large or many small moles.       - Having a family history of unusual moles (atypical nevus syndrome).       - Having a family or personal history of melanoma.        - Being white.
                
                
                    It is not known if the following lower the risk of nonmelanoma skin cancer:
                    Sunscreen use and avoiding sun exposure    It is not known if nonmelanoma skin cancer risk is decreased by staying out of the sun, using sunscreens, or wearing protective clothing when outdoors. This is because not enough studies have been done to prove this.    Sunscreen may help decrease the amount of UV radiation to the skin. One study found that wearing sunscreen can help prevent actinic keratoses, scaly patches of skin that sometimes become squamous cell carcinoma.     The harms of using sunscreen are likely to be small and include allergic reactions to skin creams and lower levels of vitamin D made in the skin because of less sun exposure.     It is also possible that when a person uses sunscreen to avoid sunburn they may spend too much time in the sun and be exposed to harmful UV radiation.    Although protecting the skin and eyes from the sun has not been proven to lower the chance of getting skin cancer, skin experts suggest the following:            -  Use sunscreen that protects against UV radiation.     -  Do not stay out in the sun for long periods of time, especially when the sun is at its strongest.     -  Wear long sleeve shirts, long pants, sun hats, and sunglasses, when outdoors.              Chemopreventive agents     Chemoprevention is the use of drugs, vitamins, or other agents to try to reduce the risk of cancer. The following chemopreventive agents have been studied to find whether they lower the risk of nonmelanoma skin cancer:         Beta carotene      Studies of beta carotene (taken as a supplement in pills) have not shown that it prevents nonmelanoma skin cancer from forming or coming back.            Isotretinoin      High doses of isotretinoin have been shown to prevent new skin cancers in patients with xeroderma pigmentosum. However, isotretinoin has not been shown to prevent nonmelanoma skin cancers from coming back in patients previously treated for nonmelanoma skin cancers. Treatment with isotretinoin can cause serious side effects.            Selenium      Studies have shown that selenium (taken in brewer's yeast tablets) does not lower the risk of basal cell carcinoma, and may increase the risk of squamous cell carcinoma.            Celecoxib      A study of celecoxib in patients with actinic keratosis and a history of nonmelanoma skin cancer found those who took celecoxib had slightly lower rates of recurrent nonmelanoma skin cancers. Celecoxib may have serious side effects on the heart and blood vessels.             Alpha-difluoromethylornithine (DFMO)      A study of alpha-difluoromethylornithine (DFMO) in patients with a history of nonmelanoma skin cancer showed that those who took DFMO had lower rates of nonmelanoma skin cancers coming back than those who took a placebo. DFMO may cause hearing loss which is usually temporary.            Nicotinamide (vitamin B3)      Studies have shown that nicotinamide (vitamin B3) helps prevent new actinic keratoses lesions from forming in people who had four or fewer actinic lesions before taking nicotinamide. More studies are needed to find out if nicotinamide prevents nonmelanoma skin cancer from forming or coming back.
                
                
                    It is not known if the following lower the risk of melanoma:
                    Sunscreen    It has not been proven that using sunscreen to prevent sunburn can protect against melanoma caused by UV radiation. Other risk factors such as having skin that burns easily, having a large number of benign moles, or having atypical nevi may also play a role in whether melanoma forms.       Counseling and protecting the skin from the sun    It is not known if people who receive counseling or information about avoiding sun exposure make changes in their behavior to protect their skin from the sun.
                
                
                    Cancer prevention clinical trials are used to study ways to prevent cancer.
                    Cancer prevention clinical trials are used to study ways to lower the risk of developing certain types of cancer. Some cancer prevention trials are conducted with healthy people who have not had cancer but who have an increased risk for cancer. Other prevention trials are conducted with people who have had cancer and are trying to prevent another cancer of the same type or to lower their chance of developing a new type of cancer. Other trials are done with healthy volunteers who are not known to have any risk factors for cancer.   The purpose of some cancer prevention clinical trials is to find out whether actions people take can prevent cancer. These may include eating fruits and vegetables, exercising, quitting smoking, or taking certain medicines, vitamins, minerals, or food supplements.
                
                
                    New ways to prevent skin cancer are being studied in clinical trials.
                    Clinical trials are taking place in many parts of the country. Information about clinical trials can be found in the Clinical Trials section of the NCI Web site. Check NCI's list of cancer clinical trials for nonmelanoma skin cancer prevention trials and melanoma prevention trials that are now accepting patients.