Skin Cancer
Why is skin cancer a concern for American Indians?
What are some of the various types of skin cancer?
What are the risk factors of skin cancer?
What are the signs/symptoms of skin cancer?
What can you do to prevent getting skin cancer?
Skin cancer is a disease in which skin cells lose the ability to divide and grow normally. Healthy skin cells normally divide in an orderly way to replace dead cells and grow new skin. Abnormal cells can grow out of control and form a mass or 'tumor'. When abnormal cells originate in the skin, the mass is called a skin tumor.
A skin tumor is considered benign if it is limited to a few cell layers and does not invade surrounding tissues or organs. But if the tumor spreads to surrounding tissues it is considered malignant or cancerous.
Cancer cells crowd out and destroy nearby healthy cells forming growths called malignant tumors.
Most skin growths, however, are non-malignant, benign (not harmful) tumors.
- Some forms of skin cancer also metastasize. That is, they spread to other parts of the body and start new tumors.
- Skin cancer that spreads to vital organs like the brain or liver can be life threatening.
The skin, which is the human body's largest organ, has several functions. It prevents the body from losing water and other fluid, stores fat, cools the body when sweat evaporates, and makes vitamin D. The skin also protects the body from infection, light, and injury.
There are three layers of skin:
- Epidermis - the outer layer of skin
- Dermis - the middle layer of the skin; contains nerves, blood vessels, sweat glands, hair follicles, and oil-producing cells that keep the skin from drying out
- Fatty layer - the deep layer of skin
Skin cancer begins in the epidermis, the outer layer of skin. The epidermis has three kinds of cells.
- Squamous cells are cells that progressively flatten and fill with protective keratin (a tough, insoluble protein that makes skin almost completely waterproof) to form the outmost surface of the skin.
- Basal cells are small cells located at the base of the epidermis that serve as a reservoir for squamous cells shed from the skin.
- Melanocytes are cells that produce a dark material, or pigment, that gives the skin its color.
Each of these cells can suddenly start to divide abnormally and become cancerous. The main types of skin cancer are named after these cells.
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Ultraviolet (UV) radiation from the sun is the main cause of skin cancer. Energy from the sun actually is a form of radiation. It consists of visible light and other rays that people can't see. Invisible infrared radiation, for instance, makes sunlight feel hot. UV also is invisible, and causes sunburn and sun tan.
UV rays damage DNA, the genetic material that makes up genes. Genes control the growth and overall health of skin cells. If the genetic damage is severe, a normal skin cell may begin to grow in the uncontrolled, disorderly way of cancer cells. UV also can cause sunburn, and other damage that makes the skin look prematurely old and wrinkled.
Two kinds of rays exist in ultraviolet radiation:
- Ultraviolet A (UVA)
- Ultraviolet B (UVB)
Scientists once thought that excessive exposure to UVB rays was the main cause of skin cancer. Now they think that UVA also is involved. That's why it is important to use a sunscreen product that protects against both UVA and UVB rays.
Some cases of skin cancer, however, may be hereditary and run in families. In those cases, skin cancer is caused by abnormal genes that children inherit from their parents. Genes make parents and children look somewhat alike. They also make them likely to get some of the same diseases.
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What are some of the various types of skin cancer?
There are a number of different types of skin cancers depending on the type of skin cell from which they arise. Each kind of skin cancer has its own distinctive appearance. Certain skin cancers also tend to develop in specific areas of the body.
- Basal cell carcinoma
- Squamous cell carcinoma
- A third type, malignant melanoma, is relatively rare but can be very dangerous.
Basal cell carcinoma and squamous cell carcinoma are called nonmelanoma to set them apart from the more serious melanoma skin cancers.
- Basal cell carcinoma is the most common kind of skin cancer. More than 90 per cent of all skin cancers in the United States are basal cell carcinomas. Fortunately, basal cell carcinoma also is the least serious kind of skin cancer. That's because it grows slowly and rarely spreads. It spreads in less than 1 out of every 1,000 patients.
- Squamous cell carcinoma is more serious because it does spread to vital organs inside the body. Spread occurs in a few cases in every 100. It does so slowly. At first cancer cells tend to spread only as far as the nearest lymph nodes structures, which filter out and trap the cancer cells. If spread has occurred, the affected lymph nodes can be removed before cancer spreads to vital organs.
- Malignant melanoma is the most serious kind of skin cancer because it may spread quickly from the skin through the lymph nodes or blood, to internal organs.
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What are the risk factors of skin cancer?
Anyone can get skin cancer. Although most cases occur in people over age 50 with fair skin, it can develop in younger people, and those with dark skin. In general, an individual's lifetime exposure to UV light determines his risk.
Certain individuals have a risk that is higher than the rest of the population. Included are people who:
- Have light skin that freckles easily and tends to burn rather than tan. Individuals with blond or red hair and blue or light gray eyes often have fair skin. The skin type table can help determine an individual's risk.
- Live in geographic regions closer to the equator, where sunlight is strongest. Residents of Florida, Texas, and southern California, for instance, have a greater risk than those in Maine, Wisconsin, and North Dakota.
- Work outdoors or spend lots of time in leisure activities in the sun.
- Already have had skin cancer. A diagnosis of skin cancer means that an individual has a higher-than-normal risk for the disease. These individuals must take great care to minimize UV exposure and follow other preventive measures.
The risk of skin cancer also varies with the kind of sun exposure.
- Basal cell carcinoma and squamous cell carcinoma are more common in people who spend a lot of time in the sun over many years. This includes people who work outdoors or engage in other daily outdoor activities in warm climates.
- Malignant melanoma is more common in people who get occasional, high-intensity sun exposure. People who sunbathe on vacations or during brief sunny periods in cold climates may get such exposure.
- Some studies show that a single serious sunburn can increase the risk of skin cancer by 50 percent.
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The most important preventive measure is to avoid excessive exposure to the sun. Ultraviolet (UV) radiation in sunlight damages the genetic material DNA in skin cell genes. This increases the risk that a normal cell will start growing abnormally and become cancerous. UV rays also damage the structure of the skin in ways that cause premature skin aging and wrinkling.
Prevention must begin in childhood. That's because most people get about 50% of their lifetime sun exposure before age 18.
Practical measures to prevent skin cancer include:
- Staying out of the sun, especially between 11 a.m. and 3 p.m., when the strongest UV rays reach Earth's surface.
- Avoiding both direct sunlight, and sunlight reflected from water, sand and snow. It also can damage the skin.
- Shielding the skin with tightly knit clothing. Long-sleeved garments made from light fabric can protect the skin in summer and yet be cool and comfortable. Hats with broad brims can shield the face.
- Using sunscreen. Pick a sunscreen that provides "broad spectrum" protection against both kinds of UV radiation in sunlight, UVA and UVB.
Your chances of finding skin cancer can be improved by performing a regular simple skin test.
Check your entire body, not just the readily visible areas. This check should include the back, the scalp, between the buttocks, and the genital area. This should take no more than 15 minutes.
- Look at the front and back of your body in the mirror, then raise your arms and look at the left and right sides.
- Bend your elbows and look carefully at your palms; forearms, including the undersides; and the upper arms.
- Examine the back and front of your legs. Also look between your buttocks and around your genital area.
- Sit and closely examine your feet, including the soles and the spaces between the toes.
- Look at your face, neck and scalp. You may want to use a comb or a blow dryer to move hair so that you can see better.
By checking your skin regularly, you will become familiar with what is normal. If you find anything unusual, see your doctor right away. Remember, the earlier skin cancer is found, the better the chance for cure.
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What are the signs / symptoms of skin cancer?
Skin cancer first appears as a growth, or abnormal accumulation of cells. It sometimes takes the form of a sore or pimple that does not heal. The sore may bleed or ooze fluid, crust or scab over, and then ooze or bleed again. Cancer can occur on almost area of the skin, but is most common on areas often exposed to the sun. Skin cancer usually is painless.
The most common symptoms of skin cancer are:
- A new growth on the skin.
- A change in an existing skin growth.
- A sore that does not heal.
Not all changes in the skin are symptoms of skin cancer. Most moles and other growths are harmless and do not need to be removed. The average person has dozens of moles and other skin growths that are benign or noncancerous. They include:
- Birthmarks, or "congenital nevi," are moles that are present at birth.
- Acquired moles begin to develop early in adolescence, growing and darkening throughout the teenage years. Many adults have 40-60 acquired moles.
- Liver spots, or "solar lentigines," are flat tan-to-brown spots that occur mainly on the face, neck, hands, and forearms. They have nothing to do with the liver. Rather, they develop as a result of aging and sun exposure.
- Seborrheic keratoses are raised, wart-like, tan-to-brown growths that occur as people age.
- Acquired cherry angiomas are smooth, dome-shaped red spots that usually develop on the chest and back. Most are bright red, and appear as people age.
- Skin tags are small, soft flaps of skin that grow on the neck, in the armpits, and groin area are caused by repeated friction.
- Actinic keratoses are slightly scaly, reddish patches that form on people with sun-damaged skin. They are precancerousgrowths that may changes into a squamous cell carcinoma. That's why doctors recommend removal of actinic keratoses.
How Can You Tell If A Mole Is Cancerous?
Although most skin growths are not cancer, it's important to check with the doctor about new growths or changes in old growths. When growths become cancerous, they may change in size or color, or become sores that do not heal.
Doing regular skin self-examinations are a good way to monitor the skin for early symptoms of skin cancer. Skin self examination is especially important for people who have had skin cancer. It can detect new cancers, and recurrences of past cancer, at an early and most curable stage.
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Doctors often can recognize skin cancer just by looking at it.
- Encourage your doctor to look for growths by doing a complete examination of the entire skin surface during a physical examination at least once a year; more often if you already have a past history of skin cancer.
- Many people detect skin cancer themselves while doing a regular skin self-examination. A biopsy, however, is the only certain way of identifying skin cancer, and determining the specific type of cancer. In a biopsy, the doctor removes cells or tissues for examination under a microscope. The examination usually is done by a dermatopathologist, a doctor who studies diseased tissue under a microscope.
Two types of biopsy are done for most skin cancers:
- An excisional biopsy excises, or cuts away, the entire visible growth. For small nonmelanoma skin cancer, an excisional biopsy may also be the only treatment necessary, whereas other cancers like malignant melanoma generally require additional removal of a wider margin of normal tissue around the site.
- An incisional biopsy, or core biopsy, removes only a sample of the growth. Further treatment is necessary if the microscopic examination reveals cancer cells. This is the most common type of biopsy.
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What treatments are available for skin cancer?
Treatment for skin cancer depends on the
- type of skin cancer
- its stage and location and the
- individual's age and overall health
Three kinds of treatment are used for most skin cancers. They re:
- Surgery: Taking out or destroying the cancer.
- Chemotherapy: Giving drugs to kill the cancer cells.
- Radiation therapy: Using powerful energy from x-rays or other sources to destroy the cancer cells.
In addition to these, there are other treatment options.
Surgery is the most common treatment. The doctor may use any of several surgical methods:
- Simple excision involves cutting out the tumor with a margin of surrounding normal skin to be sure it is completely removed.
- Cryosurgery (cryo = "cold") freezes and kills the cancer cells. It uses liquid nitrogen, which has a temperature of 196 degrees below zero centigrade. The extreme cold instantly kills the tumor, which falls off like a scab after the area thaws. Cryosurgery itself is painless. However, the treated area may become swollen and painful after it thaws. Cryosurgery is used mainly for small or superficial skin cancers, and to remove precancerous growths.
- Curettage and electrodessication combines two methods. In one, the doctor uses a curette, a sharp, spoon-shaped instrument, to scoop out the tumor. The area is then treated with electrodessication, applying electrical current produced by a special machine. It controls bleeding, and dehydrates and kills any cancer cells remaining near the edge of tumor area.
- Micrographic surgery (or Mohs surgery ) attempts to remove all of the tumor and as little surrounding normal tissue as possible. The doctor removes one layer of tumor, and examines it with a microscope. If cancer cells are present he removes another layer, and examines that. The process continues until all cancer cells have been removed.
- Laser surgery uses the highly focused beam of light from a laser to destroy cancer cells. It is seldom used for cancers that have not grown beyond the outer layer of the skin.
Chemotherapy means treatment with anti-cancer drugs. The treatment for skin cancer often uses anti-cancer drugs in a lotion or cream applied to the skin. This localized, or topical, chemotherapy is for superficial tumors that have not advanced beyond the top layer of the skin.
- Topical chemotherapy usually does not produce nausea or other body-wide side effects. It does cause redness and inflammation in treated parts of the skin.
- Systemic chemotherapy also may be given in a pill, injected into a muscle, or intravenous form through a needle in a vein. This body-wide, or systemic, chemotherapy can kill cancer cells that have spread outside the skin. It may cause nausea and other side effects in some individuals. Side effects are common, but can generally be controlled. This treatment is generally used only for metastic cancer.
Radiation therapy, or radiotherapy, uses a special kind of energy carried by invisible rays or particles to kill cancer cells, or keep them from growing. X-rays are the kind of radiation often used to kill skin cancer. The amounts are much higher than those used in an ordinary mammogram or chest x-ray. This therapy often is used for cancers that occur in areas difficult to treat with surgery, especially in the very elderly, who may be unable to safely undergo surgery. These include cancers on the ears, eyelids, and tip of the nose. Treatment is painless and does not make the body radioactive. Several treatments may be needed to kill all of the cancer cells.
Radiation therapy may cause:
- Rash, redness, or dryness in the area. Those changes are temporary and disappear.
- Other changes in skin texture or color may develop after radiation therapy. They may become more noticeable years later.
Other Treatments
Several other treatments may be used for skin cancer, including:
- Photodynamic therapy uses drugs that collect inside a tumor. The doctor then focuses a special light on the tumor. The light triggers a chemical reaction in the drug that destroys tumor cells, but does not harm surrounding normal tissue.
- Biological therapy tries to use the body's own natural defenses to attack and destroy cancer cells. It sometimes is called biological response modifier (BRM) therapy or immunotherapy. In one form of biological therapy, disease-fighting white blood cells are removed. The cells are grown in a laboratory and exposed to substances that boost their disease-fighting ability. The activated cells then are injected back into the body to attack the tumor. Biological therapy is used mainly for advanced forms of cancer that cannot be treated with other methods. It is available in clinical trials, studies conducted in medical centers to determine its safety and effectiveness.