Live Blog: Solar Damage and Solar Protection – Darrell S. Rigel, MD
In this live blog from the 12th Annual SDPA conference in Indianapolis, Darrell S. Rigel, MD, lectured on “Solar Damage and Solar Protection.” Here are some of the highlights.
Dr. Rigel began his lecture by outlining some key factors in melanoma epidemiology:
– There is more skin cancer than all other cancers in US
– Lifetime risk of invasive melanoma is greatly rising
– Current risk is 1/53 in 2014
– Projected risk to rise to 1/40 by 2020
– Males more at risk than women for melanoma (1/50 for men, 1/120 for women among people aged 70+)
– Overall there is an especially rapid increase among young white women and white males over age 65
– Survival rate is improving over time mostly because of early diagnosis yet more people are dying of melanoma every year.
– Melanoma is one of few cancers that are actually increasing in US.
– A melanoma the size of a dime has a 50% chance of already having metastasized.
Dr. Rigel pointed out that melanoma is one of the few cancers that we know the cause – UV exposure – and where a simple behavioral change – UV minimization – will lower the risk of cancer. Living closer to the equator causes a greater incidence of melanoma. This is referred to as “latitude importance.” Additionally, the relation of melanoma is related to total number of hours of UV radiation a person gets. Rigel noted that similar risk patterns exist in both light and dark skins individuals.
Rigel addressed the question “Are sunscreens effective at lowering melanoma?” He cited a couple of studies: once of which mice were exposed to SPF 15. Concusions showed that, yes, sunscreens are effective at lowering melanoma risk. A study was done in Australia with 1621 northern Australians participants aged 25-75. Participants all lived in Queensland, which is the province closest to the equator, so skin cancer rates are higher in this part of Australia. Participants that used sunscreen daily had half as much chance getting melanoma, compared to those who used sunscreen only when they “felt” like it. The overwhelming conclusion was that sunscreen does indeed lower the chance of melanoma.
Dr. Rigel discussed the technical and scientific difference in measuring UVA vs. UVB protection, discussing critical wavelength proportionality and high amplitude applications.
Dr. Rigel also spent time discussing the new sunscreen labeling rules from the FDA. He stressed that PAs should tell patients to look for broad spectrum, SPF 30 or higher, and water resistant for 80 minutes.
There are other key factors not taken into account that affect coverage:
– Application container
– Photostablility of the sunscreen
– Cosmetic acceptability
Dr. Rigel warned the audience to be cautious when it comes to recommendation lists online. Even companies like Consumer Reports get click-through revenues on the sunscreens they review and recommend.
Dr. Rigel also covered the history of vitamin D deficiency and talked about current supplement recommendations. He mentioned organizations and companies that claim there is a vitamin D deficiency epidemic are sponsored by the tanning bed industry. Dr. Rigel also addressed the issue of some people proposing that indoor tanning is a good source for vitamin D. Rigel pointed out that darker skinned people are more likely to be vitamin D resistant, yet lighter skinned people are more likely to go to tanning beds. Additionally, the UV radiation from tanning beds does not provide adequate levels of vitamin D, rather the type of UV used in tanning beds can cause skin cancer and other skin damage.