Skin Cancers

KEY POINTS

Skin cancer is a disease in which malignant (cancer) cells form in the tissues of the skin.

The skin is the body’s largest organ. It protects against heat, sunlight, injury, and infection. Skin also helps control body temperature and stores water, fat, and vitamin D. The skin has several layers, but the two main layers are the epidermis (upper or outer layer) and the dermis (lower or inner layer).

The epidermis is made up of 3 kinds of cells:

The dermis contains blood and lymph vessels, hair follicles, and glands.

There are several types of skin cancer.

The most common types of skin cancer are squamous cell carcinoma, which forms in the squamous cells and basal cell carcinoma, which forms in the basal cells. Squamous cell carcinoma and basal cell carcinoma are also called nonmelanoma skin cancers. Melanoma, which forms in the melanocytes, is a less common type of skin cancer that grows and spreads quickly.

Skin cancer can occur anywhere on the body, but it is most common in areas exposed to sunlight, such as the face, neck, hands, and arms.

Skin cancer is the most common cancer in the United States.

Basal cell carcinoma and squamous cell carcinoma are the most common types of skin cancer in the United States. The number of new cases of nonmelanoma skin cancer appears to be increasing every year. These nonmelanoma skin cancers can usually be cured.

The number of new cases of melanoma has been increasing for at least 40 years. Melanoma is more likely to spread to nearby tissues and other parts of the body and can be harder to cure. Finding and treating melanoma skin cancer early may help prevent death from melanoma.

Skin Cancer Prevention

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 person’s 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.

Although having a fair complexion is a risk factor for nonmelanoma and melanoma skin cancer, people of all skin colors can get skin cancer.

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:

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:

CoQ10 

Health benefits now include reducing skin cancer risk and photoaging, guarding against prostate and breast cancers, and averting endothelial dysfunction and vascular disease.

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.

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 (Vitamin A derivative - Used to treat severe acne.)

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.

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.

Information about clinical trials supported by NCI can be found on NCI’s clinical trials search webpage. Clinical trials supported by other organizations can be found on the ClinicalTrials.gov website.

About This PDQ Summary

About PDQ

Physician Data Query (PDQ) is the National Cancer Institute's (NCI's) comprehensive cancer information database. The PDQ database contains summaries of the latest published information on cancer prevention, detection, genetics, treatment, supportive care, and complementary and alternative medicine. Most summaries come in two versions. The health professional versions have detailed information written in technical language. The patient versions are written in easy-to-understand, nontechnical language. Both versions have cancer information that is accurate and up to date and most versions are also available in Spanish.

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This PDQ cancer information summary has current information about skin cancer prevention. It is meant to inform and help patients, families, and caregivers. It does not give formal guidelines or recommendations for making decisions about health care.

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The information in this patient summary was taken from the health professional version, which is reviewed regularly and updated as needed, by the PDQ Screening and Prevention Editorial Board.

Clinical Trial Information

A clinical trial is a study to answer a scientific question, such as whether one treatment is better than another. Trials are based on past studies and what has been learned in the laboratory. Each trial answers certain scientific questions in order to find new and better ways to help cancer patients. During treatment clinical trials, information is collected about the effects of a new treatment and how well it works. If a clinical trial shows that a new treatment is better than one currently being used, the new treatment may become "standard." Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.

Clinical trials can be found online at NCI's website. For more information, call the Cancer Information Service (CIS), NCI's contact center, at 1-800-4-CANCER (1-800-422-6237).

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