Julia Draznin Maltzman, MD
The Abramson Cancer Center of the University of Pennsylvania
Ultima Vez Modificado: 6 de mayo del 2013
May is the national skin cancer awareness month with special emphasis on Melanoma. Sun and ultraviolet (UV) radiation exposure can predispose to all types of skin cancers, not just melanoma. According to the most recent estimates, skin cancer is the most common type of cancer in the United States. At least 50% of all individuals aged 65 or greater, have had at least one episode of skin cancer.
Skin cancer is certainly more common in people with light colored skin, but dark skinned individuals should not think that they are immune. Dark skin has better photoprotection capability than does light skin, but it too can become hyperpigmented. Experts say that this is particularly true after an outbreak of acne, eczema, or any other inflammatory process. Most dermatologists advise darker skinned patients to use sunscreen with an SPF of 15 or greater every day.
Skin cancer can occur anywhere on the body. It is most commonly seen in places that have received the most sun exposure such as the face, neck, hands and arms. However, it can be seen in areas that don't receive much -or any - sun exposure such as the buttocks and under the fingernails or toenails. Remember, skin cancer seldom causes pain, so meticulous examination of the skin is the best screening modality.
Skin cancer can look differently depending on the skin type, site of disease, and type of cancer. The most common sign of skin cancer is any type of change on the skin: a change in color, a growth, a non-healing ulcer, or a lump. This abnormality may be smooth, waxy, or scaly. It may be red, brown, or black in color. Of course, skin goes through many changes and most of these changes are not cancerous, but anything worrisome or different should be called to the attention of a physician.
The most serious form of skin cancer, and thankfully the least common, is melanoma. However, if diagnosed and removed while it is still thin and limited to the outermost skin layer, it is almost 100% curable. Once it has metastasized, it is a fatal disease. Melanoma usually arises from a pre-existing mole or pigmented lesion. Unlike the other skin cancer, Melanoma has a hereditary component. Every adult with a family history of melanoma and existing moles should be examined regularly by a physician as early detection is essential. Doctors look for the A-B-C-D's when examining a patient. A stands for asymmetry: a suspicious mole is one that does not have symmetric and uniform color, texture, or shape throughout. B stands for borders: irregular borders may signal an abnormal mole. C is for color variation: if one mole has blue, brown, tan, pink, or even white patches to it, it should be excised. Finally, D stands for diameter: if a mole is greater that approximately 6 mm in diameter (about the size of a pencil eraser) it should be evaluated.
The most common form of skin cancer is called basal cell carcinoma and is abbreviated as BCC. These cancers arise in the basal cell, the cells at the bottom most layer of the outer skin. This type of cancer rarely metastasizes, although it can invade lymph nodes and blood vessels. Primarily, this type of cancer spreads locally and invades surrounding tissue. Depending on the location of the cancer, it can lead to severe disfigurement.
Another common type of skin cancer is called squamous cell. These cells are derived from the outer layers of the skin. Like BCC, it can spread locally and invade surrounding organs or tissues; and like melanoma, it can metastasize to other parts of the body if left unattended.
Most skin cancers develop after the age of 50, however the damaging effects of the sun begin in childhood. In a study by the FDA, (Food and Drug Administration) it was noted that most Americans receive 25% of their lifetime sun exposure before the age of 18. Furthermore, several studies have shown that sunburns early in life are associated with a greater risk of developing melanoma than sunburns later in the adult years. However, sunburns at any age can increase the individual's risk to develop skin cancer. It is not only acute sunburns that predispose to skin cancer, as chronic sun exposure can add up and cumulative sun toxicity is also associated with the development of this disease. In addition, tanning booths are a big concern, particularly for teens, and are a likely cause of the increase in cases in women in their 20s.
While we all think of sunscreen when talking about sun safety, it should not be our first line of defense. Your first line of defense should be avoidance of the sun and wearing sun protective clothing. Wearing protective clothing such as a hat, long sleeves and sun glasses is a good way to block out the sun's harmful rays, but remember that not all clothing provides protection! If you can see through a fabric, it is providing very little protection. A white T-shirt has an SPF around 7, so choose protective clothing wisely. You can buy clothes that have SPF ratings and there is a product you can put in the washer with your clothes to increase the SPF of them. One of the easiest and most sensible ways to protect yourself is to avoid exposure to the sun from 10am to 3pm.
Sunscreen should be considered a necessity, regardless of the clothing you wear. Apply it everyday- summer or winter! Sunscreen works in two different ways: physical blockers like zinc oxide and titanium dioxide, reflect sunlight away from the body and chemical sunscreens work by absorbing the sun's radiation before it can penetrate the skin.
There are hundreds of varieties of sunscreen available now and choosing among them may be a daunting task. Here are a few guidelines. No one sunscreen can offer 100% protection from the UV rays. Even with sunscreen, UV radiation can penetrate through the top few layers of skin. Therefore, most dermatologists recommend using sunscreen with other forms of protection such as clothing, hats, and shade.
The SPF in sunscreens stands for Sun Protection Factor and offers protection from the UV sunrays. SPF of 30 or greater offers the maximum protection from the sun by blocking 96% of UV, and sunscreen with SPF of 15 will block out 93% of all UV rays. It is a misconception that SPF of 15 blocks only half the amount of sun that an SPF of 30 does. An expert dermatologist explained that an SPF of 30 allows an individual to stay out in the sun twice as long as an SPF of 15 with the same protection. By extension, applying one coat of a sunscreen that has 30 SPF and one that has 15 SPF, does not provide 45 SPF. In fact, the result of the mixture is a dilution of the stronger SPF and thus lowers the overall protection offered.
Experts agree that sunscreen should be applied every two hours and after swimming, excessive sweating, and showering. Sunscreen should also be applied 15 to 20 minutes prior to going out into the sun to allow it to soak into the deeper layers of the outer skin. On average, an adult should use about two tablespoons of sunscreen for a single application. Recent evidence showed that most people get sun burned because they are not using enough sunscreen. One way to ensure adequate sun protection is to apply sunscreen and then reapply after twenty minutes. Manufacturers are no longer allowed to say a product is "waterproof" or "sweatproof". They now have to tell you how long it can last if you are wet or sweaty; the labeling will now read "water resistant" to 40 minutes or 80 minutes. That gives you guidance of when to reapply; however, you should always reapply after 2 hours as it becomes unactive at that point.
All experts agree, however, that limiting sun exposure time is by far the best method of sun protection one can follow.
Research in the US and Australia showed that sunrays have both Ultraviolet-A (UVA) and Ultraviolet-B (UVB) rays which may play a bigger role in the development of cancer than originally believed. Traditionally, UVB rays were thought to be responsible causing skin cancer. However, the affects of UVA may have been woefully underestimated. Researchers knew that UVA penetrated the skin more deeply than UVB. However, the belief was that UVA rays were less likely to be absorbed by the skin cells and therefore less likely to cause mutations in the cellular DNA. When scientists looked at the effects of UVA and UVB on the DNA from different skin cancer cells, they found that UVA in fact was responsible for many cancerous mutations. This finding has long been suspected in the dermatology world, but is now finally proven scientifically.
Dermatologists recommend that you find sunscreens that have both UVA and UVB protection. This may be labeled as "broad spectrum". Most sunscreens with SPF of 8 or greater will provide some UVA protection. To be certain, however, patients should look for parsol or benzophenones as key ingredients in sunscreens or a labeling of "broad spectrum" to ensure UVA protection.
Treatment for skin cancer almost always involves some type of surgery. In some cases, doctors can suggest radiation therapy or chemotherapy. In more advanced stages a combination of these modalities may be used.
The type of surgery used can vary depending on the dermatologist, lesion location, lesion characteristic and patient preference. Options include: curettage and electrodessication, Mohs' surgery, cryosurgery, laser therapy, or in severe case, skin grafting.
Radiation therapy is used for the treatment of skin cancers if the location of the cancer is such that surgery would be too disfiguring. Such areas may include the eyelid, tip of nose, or ears.
Topical chemotherapy is used as anticancer drugs in creams or lotions applied to the skin. These are often used for cancers limited to the top layers of the skin.
With summer around the corner, we at OncoLink, wish you all a happy and safe summer. Remember, being sun-smart is being cancer-smart!Imprima English