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 three kinds of cells:

• Squamous cells are the thin, flat cells that make up most of the epidermis.
• Basal cells are the round cells under the squamous cells.
• Melanocytes are found throughout the lower part of the epidermis. They make melanin, the pigment that gives skin its natural color. When skin is exposed to the sun, melanocytes make more pigment, causing the skin to tan, or darken.

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

Anatomy of the skin, showing the epidermis, dermis, and subcutaneous tissue. Melanocytes are in the layer of basal cells at the deepest part of the epidermis.

For more information about skin cancer, see the following:

• Skin Cancer Screening
• Skin Cancer Treatment
• Melanoma Treatment
• Genetics of Skin Cancer

There are several types of skin cancer.

There are two main types of skin cancer:

• Nonmelanoma or keratinocyte carcinoma, which includes:

  • Squamous cell carcinoma (SCC).
  • Basal cell carcinoma.
• Melanoma.

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 keratinocyte carcinoma or 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.

Avoiding risk factors and increasing protective factors may help prevent cancer.

Avoiding cancer risk factors may help prevent certain cancers. Risk factors include smoking, having 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, including people treated with immunosuppressive therapy after organ transplant.
  • 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 many moles (also called nevi).
  • Having a family history of unusual moles (atypical nevus syndrome).
  • Having a family or personal history of melanoma.
  • Being White.

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

Treatment of sun-damaged skin to prevent skin cancer:

It is not known if the following lower the risk of nonmelanoma skin cancer:

It is not known if the following lower the risk of melanoma:

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.

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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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PDQ® Screening and Prevention Editorial Board. PDQ Skin Cancer Prevention. Bethesda, MD: National Cancer Institute. Updated <MM/DD/YYYY>. Available at: https://www.cancer.gov/types/skin/patient/skin-prevention-pdq. Accessed <MM/DD/YYYY>. [PMID: 26389434]

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