Multiple: Skin Cancer

Definition
Description
Demographics
Causes and Symptoms
Diagnosis
Treatment
Prognosis
Prevention
The Future
For more information

Definition

Skin cancer is the uncontrolled growth of abnormal cells in the upper layer of the skin. It is the most common form of cancer among American adults. According to the American Cancer Society (ACS), more than a million cases of skin cancer are diagnosed each year in the United States.

Description

Skin cancers develop in the epidermis, which is the outermost layer of the skin and contains several layers of cells within itself. In these layers there are several different types of cells. Skin cancers are classified by the type of epidermal cell that is affected:

• Basal cell carcinoma (BCC). Basal cells are cells in the lowermost layer of the epidermis. Basal cell carcinoma is the single most common type of skin cancer. These cancers appear on the head, neck, and hands as small fleshy bumps, nodules, or red patches.
  
  They are slow-growing and rarely metastasize (spread to other parts of the body).
• Squamous cell carcinoma (SCC). Squamous cells are flat scale-like cells that form one or more layers in the middle layer of the epidermis. SCC is the second most common type of skin cancer. It may be preceded by precancerous patches of scaly skin called solar keratoses, which develop from overexposure to sunlight. Squamous cell carcinomas are most likely to appear on the ears, lips, tongue, mouth, or face. Unlike basal cell carcinomas, SCCs can invade deeper layers of tissue and spread to other parts of the body.
• Melanoma. Melanoma is the rarest type of skin cancer but also the deadliest. It develops in the melanocytes, which are cells in the lower part of the epidermis that produce a dark brownish-black pigment called melanin. Melanoma may appear suddenly as a dark patch on the skin or develop in or near a mole. It can spread rapidly to nearby lymph nodes and then to the liver, lungs, or brain.

Demographics

Skin cancer affects adults far more often than children; basal cell carcinoma rarely occurs in people younger than forty years of age. The average age of people diagnosed with melanoma is fifty-three; however, it is the most common cancer in women aged twenty-five to twenty-nine years and is second only to breast cancer in women aged thirty to thirty-four years.

About one in five persons in the United States will develop skin cancer in his or her lifetime. Most skin cancers—96 percent—are either basal cell carcinomas or squamous cell carcinomas. Though they rarely cause death, these two types of skin cancer cost the United States over $1.5 billion for treatment each year.

Melanoma accounts for only 4 percent of skin cancers in the United States, but it is responsible for 75 percent of deaths from skin cancer. About 8,500 Americans die each year from melanoma, 5,500 men and 3,000 women. Although melanoma is more common in women than men up to age forty, in adults over forty it is more common in men. In the United States, melanoma affects Caucasians twenty times more often than African Americans, and six times more often than Hispanics.

Risk factors for skin cancer include:

• Having fair skin that freckles or burns easily
• Living in areas that get high levels of ultraviolet radiation, such as mountainous regions or countries closer to the equator
• Having a job that requires working outdoors during daylight hours
• A family history of skin cancer
• Having a disorder that affects the immune system, or a history of radiation therapy for cancer
• Having scars or burns on the skin (Fragile skin is more easily damaged by sun.)
• Exposure to certain chemicals in the environment, including arsenic and some types of weed killers
• History of blistering sunburns in childhood or adolescence
• Having a large number of moles
• Developing solar keratoses

Causes and Symptoms

The basic cause of skin cancer is overexposure to the sun or to artificial sources of ultraviolet light like sunlamps or tanning booths. Ultraviolet light can damage the DNA, or genetic information, in skin cells, changing their genetic code and altering the function of those cells. Uncontrolled multiplication of these damaged skin cells can result in cancer.

Genetic factors are also involved. Skin color and sensitivity to the sun are inherited characteristics. In addition, melanoma is known to run

in some families. Researchers have identified mutations in genes on chromosomes 1, 9, and 12 as linked to familial melanoma.

The symptoms of basal cell and squamous cell carcinomas include:

• Waxy or pearly bumps on the face, ears, or neck
• Flat brownish patches on the chest or back
• Firm red lumps or nodules on the face, lips, ears, neck, hands or arms
• Flat patches or lesions with scaly, crusted surfaces on the face, ears, neck, hands or arms

The signs of melanoma are sometimes called the ABCDs. A mole developing into melanoma may show:

• Asymmetry. Half of the mole looks different from the other half in size, shape, or color.
• Border irregularity. The mole has a ragged or poorly defined border.
• Color. The color is not uniform; the mole has dashes of blue, red, or white mixed in with patches of brown or black.
• Diameter. The mole is larger than the end of a pencil eraser (about 6 millimeters).

Melanoma may also appear as skin growths that bleed easily or do not heal.

Diagnosis

About 80 percent of skin cancers are found by patients who notice suspicious changes in their skin and go to their doctor. To diagnose skin cancer, thedoctorwilltakeasmall sample of theabnormalskintobesenttoa laboratory for analysis under a microscope. This procedure is called a biopsy. The doctor may remove the entire growth, part of the growth, or shave a layer of cells from its surface. Biopsies are done under local anesthesia.

Treatment

Surgery is the most common treatment for skin cancer and solar keratoses. If the entire growth was removed for a biopsy, no further treatment may be needed. In some cases the cancerous areas can be removed with topical (applied directly to the skin) medications. Other treatment options include:

• Cryotherapy. This approach involves freezing the abnormal growths with liquid nitrogen.
• Standard surgery. The doctor cuts out the entire cancer and surrounding tissue. If the cancer is on the face, plastic surgery may be required later to restore the patient's appearance.
• Electrodessication. This is a form of treatment that involves desiccating, or drying out, skin cancers with an electric needle. It is usually done to treat small or shallow basal cell carcinomas.
• Laser surgery. This type of surgery is often done to treat cancers on the lips or cancers in the upper layers of the skin.
• Mohs surgery. Named for the surgeon who developed the technique in the late 1930s, Mohs surgery involves removing very thin layers of cancerous tissue and examining each layer under the microscope until all the cancer has been removed while leaving nearby healthy tissue unaffected. It is generally used for basal cell and squamous cell carcinomas.
• Radiation therapy and chemotherapy. These are used to treat metastatic melanoma and large BCCs and SCCs when surgery is not an option.

Prognosis

The prognosis of skin cancer depends on a number of factors: the patient's skin type, the type of cancer involved, the length of time before diagnosis and treatment, and the patient's overall health. In general, skin cancer is highly curable. Basal cell carcinoma and squamous cell carcinoma do not spread to other parts of the body as readily as melanoma; they have a 95 percent cure rate when treated early.

Melanoma, however, can metastasize to other parts of the body and is potentially deadly. Patients diagnosed and treated before their melanoma spreads to the lymph nodes have a five-year survival rate of 91 percent; however, those whose melanoma has spread to the lungs or liver have a five-years survival rate of only 7–10 percent, with an average life expectancy of six to nine months.

Prevention

People cannot change their skin type, but they can lower their risk of skin cancer by taking the following precautions against sun exposure:

• Avoid the use of tanning booths and sun lamps.
• Stay out of the sun between 10 a.m. and 4 p.m.
• Use a sunscreen with a sun protection factor (SPF) of 15 or higher every day. People with very fair skin should use a product with an SPF of 30 or higher.
• Apply sunscreen over the entire body thirty minutes before going outside, and reapply the product every two hours.
• Use a lip balm that contains sunscreen.
• Wear clothing that covers as much of the body as possible, including a broad-brimmed hat and sunglasses to protect the eyes.
• Keep infants under six months out of the sun altogether, and using sunscreen on infants older than six months.

Another important form of preventive care is regular self-examination of one's skin. The American Academy of Dermatology (AAD) outlines the steps:

• A person should first become familiar with his or her birthmarks, moles, freckles, and other skin blemishes in order to spot new growths or suspicious changes.
• Use a well-lit private room with a full-length mirror; take along a handheld mirror in order to see the back, buttocks, and other parts of the body that require a second mirror.
• It is important to check all parts of the body, not just those exposed to sunlight. Begin with the upper body, front and back; then the arms. Women should look underneath their breasts.
• Sitting in front of the mirror, examine the legs, genitals, soles of the feet, and the skin between the toes.
• Examine the back of the neck and scalp using the handheld mirror. Part the hair at intervals to check the entire scalp.

People with an increased risk of skin cancer should see a dermatolo-gist regularly and also ask their primary care doctor to look for changes in their skin during checkups.

The Future

Skin cancer is a major concern to doctors around the world because the rates of all types of skin cancer are increasing worldwide. These increases are partly the result of increased longevity, as the risk of skin cancer rises in

people over forty and even higher in people over sixty-five. Another factor is the ongoing popularity of tanning, whether in the sun or under artificial sunlamps. Melanoma in particular has increased around the world since the 1990s, with the highest rates as of 2008 in Australia and New Zealand.

SEE ALSO Dermatitis; Sunburn; Xeroderma pigmentosum

WORDS TO KNOW

Carcinoma: The medical term for any type of cancer that arises from the skin or from the tissues that line body cavities.

Cryotherapy: The use of extreme cold to destroy cancerous tumors or other diseased tissue. It is also called cryosurgery.

Dermatologist: A doctor who specializes in diagnosing and treating skin disorders.

Epidermis: The outermost layer of the skin.

Melanin: A brownish-black skin pigment.

Melanoma: The most serious form of skin cancer.

Metastasis (plural, metastases): A secondary tumor caused by the spread of cancer from its primary location to another part of the body.

Mohs surgery: A technique for removing skin cancers in very thin layers one at a time in order to minimize damage to healthy skin.

Solar keratoses (singular, keratosis): Rough scaly patches that appear on sun-damaged skin. They are considered precancerous.

Topical: Referring to any medication that is applied to the skin or the outside of the body.

For more information

BOOKS

Buckmaster, Marjorie L. Skin Cancer. New York: Marshall Cavendish Benchmark, 2008.

McNally, Robert A., ed. Skin Health Information for Teens. Detroit, MI: Omnigraphics, 2003.

So, Po-Lin. Skin Cancer. New York: Chelsea House, 2008.

WEBSITES

American Academy of Dermatology (AAD). Skin Cancer. Available online at http://www.aad.org/public/publications/pamphlets/sun_skin.html (accessed August 8, 2008).

American Academy of Family Physicians (AAFP). Skin Cancer: Saving Your Skin from Sun Damage. Available online at http://familydoctor.org/online/famdocen/home/common/cancer/risk/159.html (accessed August 8, 2008).

Centers for Disease Control and Prevention (CDC). Skin Cancer: Questions and Answers. Available online at http://www.cdc.gov/cancer/skin/chooseyourcover/qanda.htm (accessed August 8, 2008).

National Cancer Institute (NCI). What You Need to Know about Skin Cancer. Available online at http://www.cancer.gov/cancertopics/wyntk/skin/allpages (accessed August 8, 2008).

National Human Genome Research Institute (NHGRI). Learning about Skin Cancer. Available online at http://www.genome.gov/10000184 (accessed August 8, 2008).

National Library of Medicine (NLM). Skin Cancer. Available online at http://www.nlm.nih.gov/medlineplus/tutorials/skincancerandmelanoma/htm/index.htm (accessed August 7, 2008). This is an online tutorial with voice-over; viewers have the option of a self-playing version, a text version, or an interactive version with questions.