By Sherrif Ibrahim, MD, PhD
This is the third article in a series about skin cancer. In the first installment we discussed the three main types of skin cancer and the risk factors for their development. In the second piece, we discussed approaches for treating skin cancer, with particular focus on Mohs surgery and how it is the treatment of choice for a large percentage of cancers. In this article, we will discuss issues that revolve around the prevention of skin cancer. It is important to stress that while the cure rate for the majority of skin cancers is high, the best treatment is still prevention. Sun exposure remains the biggest risk factor for the development of almost all cases of skin cancer, and it is something that is largely preventable. While it is impossible to completely avoid sun exposure over the course of your life, understanding how to be smart about sun protection can greatly reduce your chances for having a suspicious growth appear on your skin or minimize the chances of getting a second cancer if you have already experienced a first.
The Basics – It all adds up
What we have learned over the years is that the risk of developing skin cancer is related to one’s cumulative ultraviolet exposure. In other words, imagine that the skin has a memory – a running meter of all the ultraviolet light (UV) you have been exposed to, whether from the sun or an artificial source such as a tanning lamp, and this meter starts ticking from the moment we are born. The meter is literally a gauge of how much damage has occurred to the DNA within our skin cells and, the more damage we accrue, the higher the chance for developing skin cancer. So if you want to argue that you only sit in the sun for short spurts or that you never lay out in the sun, the argument doesn’t hold, because your skin doesn’t know if you get your UV light four times for 15 minutes or once for an hour – it’s all the same (in fact, there is evidence that indicates intermittent sun exposure is worse for you). While there is some inevitable progression of sun damage in everyone’s skin, there are certainly some things to do slow the rate by which it occurs.
Much confusion revolves around the selection and proper use of sunscreens. With so many products emerging on the market, it is difficult to know which one is right. Typically, most dermatologists will recommend purchasing a sunscreen that is labeled as ‘broad spectrum,’ meaning that it blocks the two main types of UV light: UV-A and UV-B. However, testing by various consumer agencies tells us that not all broad spectrum sunscreens are created equally and great discrepancies exist between them. In an attempt to demystify the sunscreen situation, the FDA recently announced their first changes to sunscreen labeling regulations in over 30 years, (http://www.fda.gov/forconsumers/consumerupdates/ucm258416.htm). The goal is to create labeling standards to allow consumers to better understand the differences between various products, and all sunscreen companies should incorporate these changes this year. The SPF, or sun protection factor, will still remain. The SPF is a measure of how much longer it will take the average person to burn when the sunscreen is used correctly. So using a sunscreen with an SPF of 15 means that your skin can withstand 15 times the amount of sun before turning red. While it is true that an SPF of 30 filters out about 97% of the sun’s harmful rays, these numbers lose their meaning if the sunscreen is not used correctly. When sunscreens are tested to determine their SPF, they are used at 2 grams per square centimeter of skin. This translates to a great deal more sunscreen than the average person applies, or about a teaspoon of sunscreen for every square inch of exposed skin. In practice, this would mean that you would need one ounce, or about a golfball size of sunscreen to cover your face, neck, arms, and legs applied every two hours. Most sunscreens come as a 3 or 4-ounce tube, so if you are spending a day out on the boat, that would mean using an entire tube within one day. If you are applying less than this amount, than the effective SPF drops precipitously. A simpler way to think about it is if you’re still getting pink or tan while using a sunscreen, the number you are using is not high enough, or you are not applying the product in sufficient amounts.
As 2012 continues, sunscreens will be required to display a product information label similar to labels found on other foods and medications to allow for better comparison by consumers. They will not simply be able to claim ‘broad-spectrum coverage’ without giving an exact amount of both UV-A and UV-B protection. Those that do not will be labeled as follows: “Skin Cancer/Skin Aging Alert: Spending time in the sun increases your risk of skin cancer and early skin aging. This product has been shown only to help prevent sunburn, not skin cancer or early skin aging.” Other changes that the FDA has mandated include the elimination of outrageously high SPF claims such as 100 or 150, and replacing them with a maximum number of 50+, as well as providing information on what terms such as ‘waterproof’ mean and providing a time in minutes (either 40 or 80) of how long this protection lasts. Terms like ‘sweat proof’ and ‘water resistant’ will no longer be allowed.
The dermatology community as a whole has embraced these changes and sees them as a great way to help consumers better navigate the seemingly endless variety of products and get the best protection for their skin.
The Myth of the Base Tan
As spring is upon us, the lessons learned last summer are by now long forgotten. Instantly, you think before putting that sunscreen on that maybe if you just let your skin get a little base tan at the beginning of the summer or before your vacation, then you can avoid getting those painful pink burns and smearing on gobs of sunscreen. In reality, the idea that a base tan protects you from the sun’s harmful rays could not be farther from the truth. As our skin tans, it is an indication that the DNA within our skin cells is incurring damage. In other words, what signals the body to turn on the tanning response is mutations to DNA caused by UV exposure so, by definition, if you are getting tan, you are causing damage. By allowing skin to stay dark over the course of a vacation or the summer, you are continuously damaging the DNA in your skin and putting yourself at risk for developing potentially fatal skin cancer and premature aging. So for all of you beachgoers who think you are doing yourself a favor by getting that base tan, in reality you are worse off because you have removed your body’s natural warning sign to seek shade – the burn – and allowed your DNA to accrue more and more damage, ultimately increasing your chances for developing skin cancer.
But what about my Vitamin D?
The role of vitamin D in our bodies is a topic of recent debate in medicine. We are aware of the important function of vitamin D in bone health and there is some early evidence that it may be important in cancer prevention and a host of other functions. While the exact optimal dose of daily vitamin D is a still a topic of contention, what most physicians and certainly all dermatologists will agree upon is that the sun is not a healthy source to get this dose. It is true that there is production of vitamin D in the skin that occurs with sun exposure, the amount of sun needed to maximize this production is minimal and far below the amount of sun that would make a person’s skin red or tanned. Studies indicate that incidental exposure to the backs of your hands for a few minutes a week is sufficient to maintain adequate levels of vitamin D. Furthermore, common foods such as milk and orange juice are fortified with vitamin D, and vitamin supplements are cheap and readily available. So while the exact role of vitamin D and the correct amount of vitamin D are yet to be determined, what we do know is that UV exposure causes cancer, and anyone who tells you that the sun is a good way to generate vitamin D is doing a great injustice.
It’s Never Too Late to Start
Many skin cancer patients will often wonder if it is too late to start incorporating some of these changes into their lives and the answer is a resounding no. As mentioned earlier, the skin does have a running meter of sun exposure, and there is a point on that meter where the damage is so great that a skin cancer will form. The goal should be to prevent the meter from hitting that point and once you have reached that point at once spot on your body, the goal should be to prevent creating more damage at all the other places of the skin. In other words, the first skin cancer should be a wake-up call to start making life changes with respect to sun exposure in an effort to prevent additional cancers from forming. Broad brimmed hats (not baseball caps or visors), sunscreens, protective clothing, avoiding the sun between the hours of 10 a.m. and 2p.m .
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Sherrif Ibrahim, MD PhD is Assistant Professor of the URMC Department of Dermatology and the Wilmot Cancer Center. His practice is focused on procedural and surgical dermatology including the management of skin cancer with Mohs surgery.