5.4: The Basics of Skin Cancer
- Page ID
- 466602
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- Summarize the ABCDEs of melanoma and protective measures that can be taken
- Identify ADA-recommended skin care products (i.e.- SPF, Broad Spectrum terminology, UPF)
Exposure to Ultraviolet Radiation
Of all the types of ionizing radiation, people come into more contact with ultraviolet radiation. Sources of this radiation would include the sun, ultraviolet lights, and tanning beds. The sun produces three different forms of ultraviolet rays (UVA, UVB, and UVC). Fortunately, the deadliest of these three rays (UVC) never reaches the earth's surface and is absorbed by the Earth's ozone layer. However, both UVA and UVB reach the Earth's surface and impact living systems.
Both UVA and UVB are produced naturally by the sun and artificially by lamps and tanning beds. For years, sunbathers believed that UVA provided only a youthful glow, whereas UVB are responsible for sunburns. Now, the American Academy of Dermatologists has condemned the use of tanning beds and exposure to both UVA and UVB. Scientific research has correlated certain types of skin cancers (mainly basal and squamous cell carcinoma) with exposure to UVA and UVB, particularly from tanning beds. Besides skin cancer, tanning beds cause premature aging and damage to your eyes. If a tanning bed is not properly sanitized between uses, skin diseases can be transmitted from one consumer to another. UVA rays make up 95% of sunlight and are able to penetrate the skin more deeply. UVB makes up about 5% of the UV rays from the sun, doesn't penetrate the skin as far, but has a lot more energy.
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Recognizing Suspicious Skin Changes
According to the American Academy of Dermatologists, skin cancer, is the most common form of cancer. Exposure to ultraviolet rays or arsenic can cause skin diseases. Additionally, some individuals may be genetically predisposed to developing this illness (check out your family tree). Approximately 10,000 Americans a day will be diagnosed with one of the three different forms of skin cancer (basal cell carcinoma, squamous cell carcinoma, and melanoma). These types of cancer are named based on the type of skin cells that are affected. Millions of Americans have already been diagnosed with the most common form of skin cancer, basal cell carcinoma. This type of cancer grows very slowly and can spread to other parts of the body. Basal cell carcinoma frequently appears on the head and neck of a patient.
Squamous cell carcinoma appears more commonly on the face, neck, lips, and hands of the person. For females, squamous cell carcinoma typically presents on the lower leg portion. This form of skin cancer is more likely to metastasize (spread) than basal cell carcinoma. If caught early and treated, patients can easily survive both basal and squamous cell carcinomas.
Melanoma, the most serious form of skin cancer, is the least common of all skin cancers. This type of cancer usually manifests on the trunks of males and the legs of females. It can spread easily to the brain, liver, bones, abdomen, or lymph nodes. If detected early, survival rates are good and life expectancy will be normal.
Figure \(\PageIndex{2}\) compares normal pigmentations to moles that have changed into melanoma. Monthly reviews of skin lesions and seeking medical advice is key to surviving this disease. Be sure to note these visual characteristics (the ABCDEs) of skin cancer for future evaluations (life and class).
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Sunblocks and Sunscreens
UVB radiation in sunlight allows the skin to produce vitamin D. This vitamin prevents bone disorders like rickets and osteoporosis (brittle bone disease). The American Academy of Dermatology suggests vitamin D be obtained through foods or nutritional supplements. Excessive exposure to UV can be damaging and the pigment melanin, deposited in cells at the base of the epidermis, helps to protect the underlying layers of the skin from this damage. Melanin also colors the skin, variations in the amount of melanin produce colors from pale yellow to black. The darker the skin tone, the more melanin one has, and the less likely skin cancer will occur.
Sunscreens and sunblocks are designed to protect skin from ultraviolet rays. Sunblocks contain inorganic ingredients like zinc oxide or titanium dioxide. These chemicals act as UV filters by reflecting the sun's UV rays. Sunblocks can have grainy textures due to the inorganic components. The thick nature of a sunblock can make it difficult to spread evenly on the skin. Sunscreens contain organic compounds like oxybenzone, avobenzone, homosalate, and octinoxate (Figure \(\PageIndex{4}\)). By absorbing ultraviolet rays, these compounds decompose and give off heat. Sunscreens apply smoother than sunblocks. Often, manufacturers will combine sunscreen and sunblock ingredients to make their products.
Sun protection factor (SPF) measures a product's protection from UVB rays. SPF does not quantify protection from UVA radiation. The American Academy of Dermatology recommends selection of a sunscreen or sunblock with a minimum SPF of 30. This SPF value means a lotion can filter out 97% of UVB rays. A product with SPF 50 will only filter out 1 more percentage of UVB rays. Increasing an SPF factor past 30 does very little in shielding skin from UVB radiation.
Products that protect skin from UVA must be labeled as "broad spectrum." Sunblocks provide UVA and UVB protection, but sunscreens can vary on what they are effective against. Every two hours, sunscreens/sunblocks should be reapplied to the skin. Sweating and swimming can remove sunscreen/sunblock products. No sun products are waterproof, but some are labeled as being water-resistant. Consumers are encouraged to reapply these products every two hours as well.
Clothing and Other Garments
Though most people are unaware, the clothing they wear every day can serve as a barrier against harmful ultraviolet rays, although most garments offer only a little protection. The garment Ultraviolet Protection Factor (UPF) is measured by how much UVA and UVB rays come in contact with the skin. Garments that receive a good rating by the Skin Cancer Foundation's Seal of Recommendation have a UPF rating of at least 30. Fabrics that receive excellent ratings have UPF values of 50 and can block 98% of the sun's rays, allowing only 2% to penetrate the fabric to the skin.
Clothing does not protect equally. There are seven specific factors that make clothing more effective: UPF, color, construction, content, fit, coverage, and activity. Clothing that is darks or brightly colored are more likely to absorb UV rays rather than letting them penetrate to your skin. Densely woven clothing, like denim, wool, or synthetic fibers is more beneficial than tight clothing. If clothing becomes stretched, thinner, or wet, UV rays can seep through the fabric. Therefore, the thicker and looser the clothing, the more protection it will provide for the skin. Shiny polyester and lightweight silk fabrics are highly protective because they reflect radiation. Other fabrics like unbleached cotton and high-tech fabrics treated with chemical UV absorbers or dyes are also effective in shielding skin from UV exposure.
When spending large amounts of time outside, wearing long-sleeved shirts and pants offers more protection for your skin. Topping off your outfit with a wide-brimmed hat maximizes protection from UV rays and helps prevent basal and squamous cancers that often appear on the head and neck (locations that account for 90% of skin cancers). Lastly, select sunglasses certified to protect your eyes from UV rays, a good pair of sunglasses will reduce your risk of developing cataracts later in life.
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Contributors and Attributions
- Template:ContribLawson
- Emma Gibney, Jordan Radoll, Hannah Perry, and McKenna White (Furman University)
- Erin Avram (Cleveland State University)