General Information About Skin Cancer

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). Skin cancer begins in the epidermis, which is made up of three kinds of cells:

• Squamous cells: Thin, flat cells that form the top layer of the epidermis.
• Basal cells: Round cells under the squamous cells.
• Melanocytes: Cells that make melanin and are found in the lower part of the epidermis. Melanin is the pigment that gives skin its natural color. When skin is exposed to the sun, melanocytes make more pigment and cause the skin to darken.

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

Different types of cancer start in the skin.

Skin cancer may form in basal cells or squamous cells. Basal cell carcinoma and squamous cell carcinoma are the most common types of skin cancer. They are also called nonmelanoma skin cancer. Actinic keratosis is a skin condition that sometimes becomes squamous cell carcinoma.

Melanoma is less common than basal cell carcinoma or squamous cell carcinoma. It is more likely to invade nearby tissues and spread to other parts of the body.

This summary is about basal cell carcinoma, squamous cell carcinoma of the skin, and actinic keratosis.

Having a fair complexion and being exposed to sunlight are risk factors for basal cell carcinoma and squamous cell carcinoma of the skin.

Anything that increases a person's chance of getting a disease is called a risk factor. Not every person with one or more of these risk factors will develop skin cancer, and it will develop in people who don't have any known risk factors. Talk with your doctor if you think you may be at risk.

Risk factors for basal cell carcinoma and squamous cell carcinoma of the skin include the following:

• 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, green, or other light-colored eyes.
  • Red or blond hair.

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

• Having a history of sunburns.
• Having a personal or family history of basal cell carcinoma, squamous cell carcinoma of the skin, actinic keratosis, familial dysplastic nevus syndrome, or unusual moles.
• Having certain changes in the genes or hereditary syndromes, such as basal cell nevus syndrome, that are linked to skin cancer.
• Having skin inflammation that has lasted for long periods of time.
• Having a weakened immune system.
• Being exposed to arsenic.
• Past treatment with radiation.

Older age is the main risk factor for most cancers. The chance of getting cancer increases as you get older.

Basal cell carcinoma, squamous cell carcinoma of the skin, and actinic keratosis often appear as a change in the skin.

Not all changes in the skin are a sign of basal cell carcinoma, squamous cell carcinoma of the skin, or actinic keratosis. Check with your doctor if you notice any changes in your skin.

Signs of basal cell carcinoma and squamous cell carcinoma of the skin include the following:

• A sore that does not heal.
• Areas of the skin that are:
  • Raised, smooth, shiny, and look pearly.
  • Firm and look like a scar, and may be white, yellow, or waxy.
  • Raised and red or reddish-brown.
  • Scaly, bleeding, or crusty.

Basal cell carcinoma and squamous cell carcinoma of the skin occur most often in areas of the skin exposed to the sun, such as the nose, ears, lower lip, or top of the hands.

Signs of actinic keratosis include the following:

• A rough, red, pink, or brown, scaly patch on the skin that may be flat or raised.
• Cracking or peeling of the lower lip that is not helped by lip balm or petroleum jelly.

Actinic keratosis occurs most commonly on the face or the top of the hands.

Tests or procedures that examine the skin are used to diagnose basal cell carcinoma and squamous cell carcinoma of the skin.

In addition to asking about your personal and family health history and doing a physical exam, your doctor may perform the following tests and procedures:

• Skin exam: An exam of the skin for bumps or spots that look abnormal in color, size, shape, or texture.
• Skin biopsy: All or part of the abnormal-looking growth is cut from the skin and viewed under a microscope by a pathologist to check for signs of cancer. There are four main types of skin biopsies:
  • Shave biopsy: A sterile razor blade is used to “shave-off” the abnormal-looking growth.
  • Punch biopsy: A special instrument called a punch or a trephine is used to remove a circle of tissue from the abnormal-looking growth.
  • Incisional biopsy: A scalpel is used to remove part of a growth.
  • Excisional biopsy: A scalpel is used to remove the entire growth.

Certain factors affect prognosis (chance of recovery) and treatment options.

The prognosis for squamous cell carcinoma of the skin depends mostly on the following:

• Stage of the cancer.
• Whether the patient is immunosuppressed.
• Whether the patient uses tobacco.
• The patient's general health.

Treatment options for basal cell carcinoma and squamous cell carcinoma of the skin depend on the following:

• The type of cancer.
• The stage of the cancer, for squamous cell carcinoma.
• The size of the tumor and what part of the body it affects.
• The patient’s general health.