Skin Cancer Can Be Called Unrecognized Epidemic
By Yvan Silva, M.D.

The prevalence and the diagnosis of skin cancer is being made with such increasing frequency that skin cancer has been labeled an unrecognized epidemic by leaders in the field of dermatology. The common types of skin cancers that were usually found in people in their 50s are now being seen with increasing frequency in younger adults. Skin damage from ultraviolet (UV) radiation that occurs in the first two or three decades may not manifest until midlife or even later. While this news might seem a bit over emphatic about the problem of sun and skin cancers, just think back to the days when health concerns about smoking were thought of as just another unnecessary scare. The truth is that deep, dark tans are really out of a time warp, holdovers from the 1970s when bronzed sun worshippers were featured on the covers of fashion magazines, inspiring the envy of many, implying a social upper class that was rich and beautiful.

One in five Americans will develop cancer in a lifetime. In 2004, 1.3 million or so Americans were diagnosed with skin cancer and the death rate was about 9,000. A recent survey showed that 13 percent of children, 12 or younger, have experienced at least one episode of sunburn and that 24 percent of parents admit they've never used sunscreen to protect their children. Studies have shown that 80 percent of the damage to skin has occurred in people before they're 18 to 20 years old. Five or more episodes of sunburn will double the risk of

skin cancer. That damage is lasting because it is cumulative - the more you burn, the more the risk of cancer. Overall, the risk increases with aging because of the cumulative effects of sun exposure over time. In spite of public education, the increase continues. Screening programs have not had the intended results - skin cancers when detected are not smaller in size, as would be expected, and cancers found on the torso (while most often cancers occur in areas exposed to the sun like the head and neck) lead to the suspicion that artificial tanning may be involved.

The skin is the body's largest organ, a living envelope that protects from injury and infection and works in temperature regulation. The topmost layer, the epidermis, consists of cells that shed as younger ones develop in layers below them and grow outward. Skin coloration is controlled by melanocytes that produce the pigment melanin. Sun exposure excites the production of increased melanin that creates the tanned appearance. And the ensuing cell damage may cause new formed cells to grow in a disorderly fashion to produce cancers in the skin.

There are three forms of ultraviolet rays from the sun. These wavelength bands, UVA, UVB, and UVC, must filter through the ozone layer to reach the earth. UVC is filtered out for the most part; ozone depletion may be responsible for increased UVAand UVB reaching us. UVB is the most damaging of the sun's burning rays; it is known to cause changes in skin cells' DNA leading to mutation of genes called oncogenes that induce malignant change. UVB rays are linked to sunburn that can result in squamous and basal cell cancers. They are not the sole cause. UVA is the second form of UV radiation; these rays penetrate deeper into the skin and weaken its immune system, setting the stage for cancers like melanoma. When damage to the melanocytes occur, these cells may not be able to repair themselves, making them susceptible to cancer formation. Tanning beds run machines with high dose UVA; some of them also emit UVB. Intense exposure, although it may be occasional, poses a greater risk to melanoma than tanning in the sun.

Basal cell carcinoma is the most common form of skin cancer, accounting for 80 percent of all skin cancers. In 1999, 900,000 new cases were diagnosed. The skin cancer looks like a pearly nodule that may gradually grow. A small area that is raw and won't heal may appear, or the cancer can actually look like a chronic sore. It usually occurs in areas exposed to sun for many, many years. Depending on their size, these can be treated by freezing or surgical removal. The outcomes of cure are excellent, and 95 percent can be cured.

Squamous cell carcinoma is the second most common form. 200,000 cases were discovered in 1998, representing 16 percent of all skin cancers. The disease is 95 percent curable if treated early, but it can spread and is potentially lethal if left untreated. Like basal cell cancer, it occurs in people who have had chronic sun exposure through their lives, and it looks like a scaly, crusty patch with a callused, hard surface. It is treated by freezing or by surgery.

Melanoma is the least common form of the disease, but it is the most deadly. The odds of getting melanoma are about 1:80 and occurrence is linked to sun exposure. People who have had several blistering sunburns in their youth or adolescence are at risk for melanoma as well as those with a family history of the problem. It usually begins as a pigmented mole, sometimes with an uneven border. The color and size may change over time. Important signs are asymmetry, irregularity of borders, varied colors within the area, ulceration, and enlarging of the spot. Melanoma grows downward from the surface into the skin depth. The deeper it extends, the more likely for it to have spread. Spread to various sites in the body occurs through the bloodstream. Management consists of establishing a tissue diagnosis by biopsy and a wide excision of the skin lesion with skin grafts if needed. In the case of spread, chemotherapy, radiation, and other treatments are used.

Skin cancer, if not completely preventable, can be treated successfully if caught early. There are several ways to protect skin from the ravages of sunburn. Cover up as much as you can with tightly woven protective clothing with long pants and sleeves. A head cover with a four-inch brim can protect your face and neck. Wear sunglasses. Apply a suncreen if you're out in the sun for more than 20 minutes. Professionals recommend an SPF rating of at least 15; some types are available with ratings as high as 60. Apply it 15 to 30 minutes before exposure. Cover all exposed parts of your body and reapply if you've been sweating, swimming, or if you've been outside longer than two hours. It is best to minimize exposure to the sun between 10 a.m. and 4 p.m., when the rays are the strongest.

People who have or are concerned about skin lesions should examine themselves for dark spots and moles and look especially for changes over the periods of observation. It is essential to make sure that the whole body is checked thoroughly and not miss any areas. A mirror can help and another observer may be required to help with hidden areas. Any suspicious skin lesion should be examined by a qualified practitioner.

We do not pay enough attention to our skin. Most interestingly Skin as our largest organ, does perform many functions besides just providing a covering for the body. It accounts for 15 percent of body weight. It renews itself constantly, about once a month. Young cells are produced in the bottom layer and rise to the surface as they age and change into a lifeless protein called keratin, which sheds as it flakes off. Hair, fingernails, and toenails also contain keratin, and they grow very rapidly like skin.

Skin cancer is the most common form of all cancer, accounting for nearly half of all cancers. Take good care of your skin. And more importantly, protect children from sunburn. That is the best of prevention, as we know it.

Dr. Silva is a professor of surgery at Wayne State University and a resident of Woodbluff on Mackinac Island.