M. D. Anderson Cancer Center
Date: May 2009
Duration: 0 / 04:05
Return to Focused on Health
From the University of Texas M. D. Anderson Cancer Center, we are Focused on Health.
Avoiding sun exposure is the best way to reduce your skin cancer risks. Complete avoidance isn’t practical, so at least avoid the sun from 10 a.m. to 4 p.m., especially during the summer months. Wearing sun protective clothing, such as a wide-brimmed hat, long sleeved shirt and pants, and UV-protective sunglasses is another important step. Sunscreen, while still important, is the last line of defense. Remember that sunscreen should have a sun protection factor, or SPF, of 15 or higher, and be properly applied and reapplied to be effective.
Apply at least one ounce of sunscreen 30 minutes before sun exposure. An ounce is the size of a ping pong ball and will adequately cover your exposed skin. Applying your sunscreen before you go out gives your skin time to absorb it. Sunscreen should be reapplied every two hours or more frequently when you are sweating or in the water, even if your sunscreen claims it is water or sweat-proof.
Sunscreens provide either physical or chemical protection from the sun’s rays. Physical sunscreens contain mineral particles that reflect and scatter light. Sunlight is unable to penetrate these barriers so the skin remains protected. Look for zinc oxide or titanium dioxide on the sunscreen label. Chemical sunscreens absorb and remit the light but may cause sensitivity in some individuals. Look for salicylate, cinnamate or benzophenone on the sunscreen label.
Ultraviolet radiation occurs in three wavelengths, A, B and C. UV-A ages the skin and is associated with allergic reactions to sunlight. UV-B causes sunburns. UV-C is absorbed in the atmosphere and does not pose a risk to your skin. Both UV-A and UV-B radiation are associated with skin cancer. Choose a broad spectrum sunscreen that protects you from both UV-A and UV-B rays.
Sunscreen doesn’t provide 100 percent protection from UV radiation. It doesn’t allow you to stay longer in the sun. It just protects you from sunburn. SPF is the ratio of time it takes the skin to burn with and without sunscreen. SPF protection does not increase proportionately with the SPF number. For example, SPF 15 absorbs 93 percent of the sun’s burning rays, while SPF 30 absorbs 97 percent.
The SPF number on sunscreens only reflects the product’s screening ability for UV-B rays. Currently, there is no FDA-approved rating system that identifies UV-A protection.
It’s true that your body relies on the ultraviolet radiation of the sun to make vitamin D. Sunscreens do not interfere with this process because they do not block 100 percent of the sun’s UV radiation. Studies have shown that individuals who used sunscreen, sun protective clothing and avoided the midday sun still maintained adequate levels of vitamin D year-round. If you have concerns, ask your health care provider to test your levels of vitamin D. Supplements can be used when necessary.
Check your skin regularly and see a dermatologist once a year for a skin exam. M. D. Anderson’s Cancer Prevention Center provides skin exams as well as comprehensive cancer screening services. To make an appointment, call 1-877-MDA-6789 or submit an online patient self referral form at our Web site, www.mdanderson.org/ask.
Return to Focused on Health
© 2009 The University of Texas M. D. Anderson Cancer Center
1515 Holcombe Blvd, Houston, TX 77030
1-800-392-1611 (USA) / 1-713-792-6161