Jane Brody on health and aging.
With summer sun shining brightly across the United States (at least on most days), there is no better time to review the latest sobering findings on the damage that ultraviolet radiation can inflict on one’s skin and then take steps to prevent it.
Skin Danger from the Sun
Energy from the Sun is the source of life
but it is also a source of danger
when Its penetrating rays slice like a knife
to becoming a molecule dis-arranger
causing mutations
and cellular aberrations
like some whirling malignant dancer.
that ultimately bring cancer
So, if there is one simple lesson those older can teach
it's 'cover up well when on the beach'
or here's a simpler bet for woman and man:
Never, ever, try to get a sun tan.
Stay pale matter how it may your mirror dismay,
you'll be much better off in fifty shades of gray.
hzl
7/1/15
(PS: Written one day after MOHS surgery, my third such and counting...))
A British research team
reported in May in the journal Science that a quarter or more of cells in the skin of middle-aged people have suffered sun-induced DNA damage. Although the cells were outwardly normal, the mutations that occurred could be the first stages of cancer.
The researchers, led by
Dr. Peter J. Campbell, a cancer geneticist at the
Wellcome Trust Sanger Institute in England, examined the eyelid skin of four middle-aged adults — three were Western European and one was of South Asian descent — and found that hundreds of ostensibly normal cells had mutations linked to cancer, a number “way higher than we’d expect,” Dr. Campbell said. Clusters of these mutant cells, called clones, appeared in every 0.1 square inch of skin, with thousands of DNA mutations in each cell.
Although it is not known if the same rate of mutations occurs in sun-exposed skin elsewhere on the body, or in people of different ethnic backgrounds, or even how many of the mutations would progress to cancer, it is not a finding to dismiss lightly.
Douglas E. Brash, a biophysicist at Yale University School of Medicine who has studied ultraviolet damage to cells for more than 40 years and
wrote a commentary on the British study, described the new findings as “a canary in a coal mine” and a warning to take the effects of ultraviolet radiation, whether from sunlight or tanning beds, more seriously.
It is especially important, he said, “to be very conscientious about protecting young children,” who are more susceptible than teenagers and adults to ultraviolet-induced mutations.
“A lot of damage occurs when people go to the beach,” Dr. Brash said. “While the body does a great job of repairing the damage and gets 99.9 percent of things right, every once in a while, you do get a mutation that may make a cell resistant to death, allowing it to form a clone that can become a cancer.”
Complicating the matter is that many people don’t understand the meaning of the S.P.F. rating listed on modern sunscreens — only 43 percent of 114 people
surveyed at a dermatology clinic in Illinois last summer, according to a study in JAMA Dermatology. The rating, which stands for sun protection factor, is meant to reflect how well a product protects against sunburn, which should also reduce the risk of skin cancer and sun-induced skin aging. And less than a third of people use sunscreen regularly,
according to the Centers for Disease Control and Prevention.
Dermatologists have long cautioned people not to rely too heavily on sunscreens, even products with the recommended S.P.F. rating of 30 or higher for summer sun protection. Few people who do use sunscreen use enough to achieve the level of protection measured in the laboratory, and few reapply it often enough. A better plan is to stay out of the sun, especially midday, and cover the skin when sun exposure is unavoidable.
Furthermore, a
recently published study by Dr. Brash’s team at Yaleshowed that much of the harm to skin cells caused by ultraviolet radiation occurs hours after the exposure has ended. Even in the dark, substances formed during UV exposure continue to damage melanin, the pigment that gives skin its color, “exciting electrons, the energy from which gets transferred to DNA and can damage it in the same way that UV photons do,” Dr. Brash explained.
The British researchers chose eyelid skin for their study because it is readily available from an operation called
blepharoplasty to remove drooping upper eyelids. Using a sophisticated technique called ultradeep sequencing, the researchers analyzed 234 biopsies from normal skin tissue for 74 cancer genes, and found a level of mutations “similar to that seen in many cancers.” A lot of the genetic changes they found resulted in what is called “driver mutations” that are capable of forming clones, a major step toward forming cancers.
Dr. Brash said skin on the hands, arms, cheeks and ears is likely to be even more heavily exposed to UV radiation than eyelid skin, and thus may have even higher levels of mutations, since the eyelids are shaded in part by the eye socket and sometimes sunglasses.
Nearly 25 years ago, Dr. Brash and his co-workers reported that UV light induced mutations in the critically important tumor suppressor gene called p53. They examined
squamous cell skin cancers from 24 patients in New England and Sweden and found that 58 percent had mutations in p53, including a particular change in DNA structure “unique to UV.”
“You can’t buy a cream to get rid of mutations, so the best approach is to prevent the damage,” Dr. Brash said. “The new study presents a graphic picture of what’s going on in our skin, and might convince people to put on sunscreen and stay off the beach between 10 and 2.”
In its
latest analysis of 1,000 commercially available sunscreens, the Environmental Working Group, a consumer advocacy organization based in Washington, rated sunscreens made with zinc oxide or titanium oxide high because “they provide strong sun protection with few health concerns” and “they don’t break down in the sun.” These substances are also more protective than other sunscreen ingredients against UVA rays, which can cause aging of the skin and immune suppression and characteristic sun-induced mutations in skin cells. The group’s complete 2015 sunscreen guide is available online at
ewg.org/2015sunscreen.
Some consumers erroneously believe that choosing a more expensive sunscreen with a sky-high S.P.F. number like 70 or 100 will provide complete protection. However, the
Food and Drug Administration has not determined that an S.P.F. of more than 50 has any added benefits.
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