About skin cancer

Skin cancer is the most common type of cancer in the United States. Each year, about 3.5 million cases of skin cancer are diagnosed. Most skin cancers are non-melanoma, and if caught early, may be treated by a dermatologist in an outpatient procedure. Melanoma comprises only about 1 percent of all skin cancers, but it is responsible for more than 90 percent of skin cancer deaths.

Skin cancer occurs when the body does not repair damage to the DNA inside skin cells, allowing the cells to divide and grow uncontrollably. Skin cell damage may be caused by a variety of factors, including genetics and skin type. Most cases of skin cancer result from overexposure to ultraviolet (UV) light produced by the sun. Skin cancer may appear as a dark spot, lesion, a wound that does not heal or a bump on the skin.

What causes skin cancer?

The primary risk factor for melanoma and non-melanoma skin cancers is exposure to ultraviolet (UV) light, including sunlight and tanning beds, with the risk growing with the amount of exposure.

Besides sun exposure, common skin cancer risk factors include:

• Weakened immune system, from viruses, diseases or immune-suppression therapy associated with organ transplantation
• Moles
• Personal or family history of skin cancer
• Inherited conditions, such as xeroderma pigmentosum
• Smoking tobacco
• Chemical exposure to items such as arsenic, industrial tar, coal, paraffin and certain types of oil
• Basal cell nervous syndrome, also called Gorlin syndrome
• Human papilloma virus (HPV)
• Kaposi sarcoma associated herpesvirus
• Radiation therapy exposure
• Psoriasis treatment

Who gets skin cancer?

Caucasians are at greater risk of developing skin cancer than people with darker skin. The risk of skin cancer is also higher for individuals with blond or red hair, blue or green eyes, or fair skin that burns or freckles easily.

Skin cancer risks increase as you age, likely due to accumulated UV radiation from sun exposure.

People who live in areas with bright, year-round sun exposure, or those who spend a lot of time outdoors without sun protection or sunscreen, are at greater risk. Early exposure, particularly for people who had frequent sunburns during childhood, also increases skin cancer risks. Skin cancers may also be found in younger individuals who spend a lot of time in the sun. Doctors often recommend a broad spectrum sunblock with a sun protection factor (SPF) of 30 or higher and protective clothing as forms of skin cancer prevention.

Men are twice as likely to develop basal cell carcinomas and three times more likely to develop squamous cell carcinomas than women.

Skin cancer types

Common types of skin cancer include:

• Basal cell carcinoma (BCC), which accounts for more than 80 percent of skin cancers diagnosed each year and tends to develop on parts of the body with the most sun exposure
• Recurrent basal cell carcinoma, either in the same location or elsewhere in the body
• Squamous cell carcinoma (SCC), which is more likely than basal cell carcinoma to invade fatty tissue beneath the skin
• Melanoma, which forms in melanocytes, the skin cells that produce the brown pigment known as melanin and darken when exposed to the sun
• Merkel cell carcinoma, which forms in cells that give skin its sense of touch and may metastasize to the brain, bones, liver or lung
• Kaposi sarcoma (KS), which is caused by human herpesvirus 8 and develops in the blood vessels of the skin
• Actinic keratosis, which is a precancerous growth that may develop into squamous cell carcinoma
• Lymphoma of the skin, also called cutaneous lymphoma, which is a type of non-Hodgkin lymphoma
• Keratoacanthoma, typically a benign (non-cancerous) tumor that goes away on its own, but is treated like squamous cell skin cancers if it continues to grow

Skin cancer symptoms

Because many skin cancers develop where they can be seen, there is a good chance of early detection. Regular examination of the skin is critical in looking for any new or unusual growths or changes in existing moles.

It is important to examine more than the legs, trunk, arms, face and neck. You should also check for signs of skin cancer between the toes, underneath the nails and on palms of the hands, soles of the feet, genitals and even the eyes.

Individuals should pay attention for warning signs of skin cancer, including:

• An unusual skin growth or sore that doesn’t go away, such as a nodule, rash or irregular patch on the surface of the skin
• A pale patch of skin or a waxy or pearly white translucent bump on the head or neck, or a brownish scar or flesh-colored lesion on the chest, which may be signs of basal cell carcinomas
• Firm, rough lumps on the surface of the skin, sometimes developing more like a reddish, scaly patch if a nodule doesn’t form, which may be signs of squamous cell carcinomas
• Red or flesh-colored moles that are raised and grow quickly, which may be a sign of Merkel cell carcinomas

Diagnosing skin cancer

Diagnosing skin cancer usually begins with a visual examination. The Skin Cancer Foundation and the American Cancer Society recommend monthly self-examinations and annual doctor visits to screen for potential skin cancer. If you are being seen by a primary care physician, you may be referred to a dermatologist who can perform more specialized tests and make a diagnosis.

A dermatologist may use a special microscope or magnifying lens to examine the suspicious spot more closely, a process called dermatoscopy. In many cases, the skin cancer is removed in the dermatologist's office.

Tests used to diagnose skin cancer include:

• Biopsy, including excisional biopsy, shave biopsy and punch biopsy
• Computed tomography scan (CT scan)
• X-ray
• Magnetic resonance imaging (MRI)

Skin cancer treatments

Most cases of skin cancer may be treated in a dermatologist's office or with outpatient surgery. If a dermatologist determines the skin cancer is melanoma or Merkel cell carcinoma, more aggressive treatment may be required.

The most common treatment options for skin cancer include:

• Surgery, including the removal of cancer cells along with a small amount of surrounding skin
• Topical treatments, including photodynamic therapy, topical chemotherapy and immune response modifier
• Chemotherapy
• Radiation therapy, including external beam radiation therapy (EBRT), intensity modulated radiation therapy (IMRT) and TomoTherapy^®
• Targeted therapy, including the use of hedgehog pathway inhibitors (not to be taken by women who are pregnant or who may become pregnant) to treat advanced basal cell carcinoma
• Immunotherapy, including the use of the cytokines alpha-interferon (IFN-alpha) and interleukin-2 (IL-2) to treat some cases of advanced melanoma