18 Apr Some SPF30 Sunscreens Protect Better Than Others

MedicalResearch.com Interview with:
Christin E. Burd, Ph.D.
Assistant Professor
Departments of Molecular Genetics, and Molecular Virology, Immunology and Medical Genetics
The Ohio State University
James Comprehensive Cancer Center
Columbus, OH 43210

MedicalResearch.com: What is the background for this study? What are the main findings?

Dr. Burd: Many melanomas develop from benign moles and exposure to ultraviolet sunlight is thought to play a major role in this process.

Initially, we were interested in determining how ultraviolet sunlight might cooperate with gene mutations found in moles to initiate melanoma. To examine this, we exposed melanoma-prone mice to a single, non-burning dose of ultraviolet (UV) light.  Our findings were quite unexpected. While the untreated mice naturally developed melanoma at 26 weeks of age, UV-treated subjects got melanoma at just 5 ½ weeks of age.

This striking result suggested to us that our model might provide a superior way to test sunscreens. SPF ratings are currently based upon the ability of a sunscreen to protect against skin burning. We know that sunburns are associated with melanoma risk, but whether protection from skin burning is enough to prevent cancer was unclear.

By applying a number of commercially available SPF30 sunscreens to our mice before UV exposure, we were able to show that the animals were protected from melanoma. However, we noticed that some SPF30 sunscreens worked better than others. In fact, many SPF30 sunscreens out-performed the one SPF50 sunscreen tested in our initial study. So while all sunscreens protect against melanoma, SPF does not predict which ones are the best.

MedicalResearch.com: What should clinicians and patients take away from your report?

Dr. Burd:

• First, patients and clinicians should be aware that even a single, non-burning dose of sunlight can cause cancer. Therefore, sun protection is a must for everyone. When exposure to the sun can’t be avoided, our findings show that sunscreens do help prevent melanoma. We suggest that consumers follow the recommendations of the American Academy of Dermatology and select a water resistant, broad-spectrum sunscreen with an SPF of 30 or higher.
• Second, the observation that some SPF30 sunscreens performed better than others in our model suggests that current testing protocols may not accurately predict the ability of these products to prevent melanoma.  We hope our findings will encourage the public to advocate for new standards in sunscreen testing – standards that more appropriately reflect the ability of these products to protect against melanoma and other skin cancers.

MedicalResearch.com: What recommendations do you have for future research as a result of this study?

Dr. Burd: Sunscreens are complex products, containing multiple active ingredients. Our next step will be to investigate which of these active ingredients provides the best cancer protection.

In addition, one caveat to our initial work is the use of a UVB filtered light source.  Sunlight contains two wavelengths of UV light: UVA and UVB, and tanning beds emit mostly UVA light. Going forward, we are interested in understanding how different forms of UV exposure contribute to melanoma onset and if the broad spectrum rating, currently used to indicate the ability of a sunscreen to block UVA, accurately reflects the protective nature of these products.

Citation:

Abstract presented at the April 2016 Annual Meeting:

Andrea M. Holderbaum, Rebecca C. Hennessey, James E. Gillahan, Anamaria Bonilla, Conor Delaney, Raleigh D. Kladney, Kathleen L. Tober, Tatiana M. Oberyszyn, Christin E. Burd. The Ohio State University, COLUMBUS, OH

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Last Updated on April 18, 2016 by Marie Benz MD FAAD