Incidence of melanoma has increased significantly
Longer days are here again, and you can feel the jubilance of people coming out of hibernation after a long, hard winter. Summer weather will be here before you know it, and millions will be heading to the beaches. What could possibly be wrong with this picture? With all of these benefits, you need to be cognizant of cutaneous (skin) melanoma. It is small in frequency, compared to basal cell and squamous cell carcinomas, responsible for only about 5 percent of skin cancers; however, it is much more deadly.
Unfortunately, melanoma is on the rise. Over the last 40 years from 1970 to 2009, its incidence has increased by 800 percent in young women and by 400 percent in young men (1). These were patients diagnosed for the first time between 18 and 39 years old. Overall, the risk is greater in men, with 1 in 37 afflicted by this disease in their lifetimes. The rate among women is 1 in 56. It is predicted that in 2014, there will be over 76,000 cases, with over 12 percent of these resulting in death (2).
Melanoma risk involves genetic and environmental factors. These include sun exposure that is intense, but intermittent; tanning beds; UVA radiation used for the treatment of psoriasis; the number of nevi (moles); Parkinson’s disease; prostate cancer; family history; and personal history. Many of these risk factors are modifiable (3).
Fortunately, melanoma is mostly preventable. What should you look for to detect melanoma at its earliest stages? In medicine, we use the mnemonic “ABCDE” to recall key factors to look for when examining moles. This stands for asymmetric borders (change in shape); border irregularities; color change; diameter increase (size change); and evolution or enlargement of diameter, color or symptoms, such as inflammation, bleeding and crustiness (4). Asymmetry, color and diameter are most important, according to guidelines developed in England (5).
It is important to look over your skin completely, not just partially, and have a dermatologist screen for potential melanoma. Screening skin for melanomas has shown a six-times greater chance of detecting them. Skin areas exposed to the sun have the highest probability of developing the disease. Men are more likely to have melanoma tumors on the back, while women are more likely to have melanoma on the lower legs, but they can develop anywhere (6).
In addition, most important to the physician, especially the dermatologist, is the thickness of melanoma. This may determine its probability to metastasize. In a recent retrospective (backward-looking) study, the results suggest that melanoma of >0.75 mm needs to not only be excised, or removed, but also have the sentinel lymph node (the closest node) biopsied to determine risk of metastases (7). A positive sentinel node biopsy occurred in 6.23 percent of those with thickness >0.75 mm, which was significantly greater than in those with thinner melanomas. When the sentinel node biopsy is positive, there is a greater than twofold increase in the risk of metastases. On the plus side, having a negative sentinel node helps relieve the stress and anxiety that the melanoma tumor has spread.
The two most valuable types of prevention are clothing and sunscreen. Let’s look at these in more detail.
Clothing can play a key role in reducing melanoma risk. The rating system for clothing protection is ultraviolet protection factor. The Skin Cancer Foundation provides a list of which laundry additives, clothing and cosmetics protect against the sun (8). Clothing that has a UPF rating between 15 and 24 is considered good, 25 to 39 is very good and 40 to 50 is excellent. The ratings assess tightness of weave, color (the darker the better), type of yarn, finishing, response to moisture, stretch and condition. The most important of these is the weave tightness (9).
Interestingly, The New York Times wrote about how major companies are producing sun-protective clothing lines that are fashionable and lighter in weight. The article is entitled “Fashionable options reshape sun-protective clothing” (10).
We have always known that sunscreen is valuable. But just how effective is it? In an Australian prospective (forward-looking) study, those who were instructed to use sun protective factor 16 sunscreen lotion on a daily basis had significantly fewer incidences of melanoma compared to the control group members, who used their own sunscreen and were allowed to apply it at their discretion (11). The number of melanomas in the treatment group was half that of the control group’s over a 10-year period. But even more significant was a 73 percent reduction in the risk of advanced-stage melanoma in the treatment group. Daily application of sunscreen was critical.
The recommendations after this study, and others like it, is that an SPF of 15 should be used daily by those who are consistently exposed to the sun and/or are at high risk for melanoma according to the American Academy of Dermatology (12). The amount used per application should be about one ounce. However, since people don’t use as much sunscreen as they should, the academy recommends an SPF of 30 or higher. Note that SPF 30 is not double the protection of SPF 15. The UVB protection of SPFs 15, 30 and 50 are 93 percent, 97 percent and 98 percent, respectively.
The problem is that SPF is a number that registers mostly the blocking of UVB, but not so much the blocking of UVA1 or UVA2 rays. However, 95 percent the sun’s rays that reach sea level are UVA. So what to do?
Sunscreens come in a variety of UV filters that are either organic filters (chemical sunscreens) or inorganic filters (physical sunscreens). The FDA now requires broad spectrum sunscreens pass a test showing they block both UVB and UVA radiation. Broad spectrum sunscreens must be least SPF 15 to decrease the risk of skin cancer and prevent premature skin aging caused by the sun. Anything over the level of SPF 50 should be referred to as 50+ (3).
The FDA also has done away with the term “waterproof.” Instead, sunscreens can be either water-resistant or very water-resistant if they provide 40 and 80 minutes of protection, respectively. This means you should reapply sunscreen if you are out in the sun for more than 80 minutes, even with the most protective sunscreen (3). Look for sunscreens that have zinc oxide, avobenzone or titanium oxide; these are the only ones that provide UVA1 protection in addition to UVA2 and UVB protection.
In conclusion, to reduce the risk of melanoma, proper clothing with tight weaving and/or sunscreen should be used. The best sunscreens are broad spectrum, as defined by the FDA, and should contain zinc oxide, avobenzone or titanium oxide to make sure the formulation not only blocks UVA2 but also UVA1 rays. It is best to reapply sunscreen every 40 to 80 minutes, depending on its rating. We can reduce the risk of melanoma occurrence significantly with these very simple steps.
(1) Mayo Clin Proc. 2012; 87:328–334. (2) CA Cancer J Clin. 2014;64:9-29. (3) uptodate.com. (4) JAMA. 2004;292:2771-2776. (5) Br J Dermatol. 1994;130:48-50. (6) Langley R. G. et al. Clinical characteristics. In: Cutaneous Melanoma, Third Edition. St. Louis, Mo., Quality Medical Publishing Inc. 1998. p. 81. (7) J Clin Oncol. 2013;31:4385-4386. (8) skincancer.org. (9) Photodermatol Photoimmunol Photomed. 2007;23:264-274. (10) nytimes.com. 2013 July 17. (11) J Clin Oncol. 2011;29:257-263. 12 aad.org.
*If you would like to see a specific topic covered in Medical Compass, please email [email protected]
Dr. Dunaief is a speaker, author and local lifestyle medicine physician focusing on the integration of medicine, nutrition, fitness and stress management. For further information, go to the website medicalcompassmd.com and/or consult your personal physician.