Do sunscreens help prevent skin cancer? Well, that depends.
Dr. John Huber thinks dermatologists have done a lousy job warning people about skin cancer. He should know -- he's a dermatologist himself.
"The relationship between ultraviolet light and skin cancer is now more firmly established than the relationship between smoking and lung cancer," says Huber, a skin cancer specialist with the Memphis Dermatology Clinic. "But we couldn't really tell people to stay out of the sun, so we tailored our message and said, well, at least use sunscreen."
Sunscreens were developed to shield skin from the two types of ultraviolet rays that cause the most damage, usually identified on the labels as UVA and UVB. The "A" rays cause skin to age, and the "B" rays cause burning.
But the lotions themselves have become part of the problem.
"Do sunscreens cause skin cancer?" asks Huber. "No. But they make people think they are a lot more protected than they really are. Sunscreens replace common sense."
But wait a minute. Just slap on some really good sunscreen, with a Sun Protection Factor (or SPF) of, say, 15, and you're good for 15 hours of cancer-free sun, right?
Absolutely wrong, says Huber. "Those numbers do not mean hours," he emphasizes. Instead, they are a multiplication factor for the protection that particular level of sunscreen provides. This is where it gets tricky. A person first has to know his own "sunburn limit" -- the time it takes before he begins to burn. And everybody is different. "A guy with light skin, red hair, and green eyes may have a SPF of just five minutes," says Huber. "Well, if he puts on a SPF 15, you multiply his five minutes times 15. He is covered for 75 minutes."
But not entirely.
"That only assumes he puts it on as thick as the manufacturer recommends, and they really want you to slather it on, like icing," says Huber. "Also, that he puts it on 30 minutes prior to sun exposure, that he doesn't get wet, that he doesn't sweat, and -- very important -- that he reapplies it frequently during the course of that 75 minutes."
Then, assuming this person -- who has perhaps gone to the beach to swim or doze on the sand, remember -- actually does all this, here's one final kicker.
"At the end of that 75 minutes," says Huber, "he is done. Once you exceed that time limit, putting on more sunscreen is not going to help."
People simply don't want to hear this. "I have a daughter myself who is fair-skinned," says Huber. "So we go to the beach and stay outside from 8 to 10 a.m., or after 4 p.m. What you want to avoid are those really intense rays from 10 a.m. to 4 p.m. But talk about a tough message -- that kids and teens are supposed to stay out of the sun during the middle of the day."
While they -- and people of all ages -- are pondering all these numbers, from the "good" hours of the day to the range of SPFs, they should consider these. According to the American Cancer Society, skin cancer is increasing at an alarming rate. In the 1950s, doctors were seeing one case of melanoma -- the deadliest form of skin cancer because it spreads so quickly -- in every 600 patients. Now that ratio has dropped to one in 60.
"There were 60,000 cases of melanoma last year, and 8,000 people died from it," says Huber. The bottom line: "The sun that people are getting these days, and the way their bodies are designed to handle it, are simply not matching up."