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Skin Cancer
Protein 'switch' suppresses skin cancer development
(Yahoo News-8/09/2008)
When IKKalpha; fails to keep cell replacement cycle in balance, cancer follows.
The protein IKKalpha (IKKa) regulates the cell cycle of keratinocytes and plays a key role in keeping these specialized skin cells from becoming malignant, researchers at The University of Texas M. D. Anderson Cancer Center report in the Sept. 9 issue of Cancer Cell.
"We have shown that IKKa acts as a sentry, monitoring and, when necessary, halting proliferation of these important cells. In the first mouse model of its kind, we also found that deleting IKKa spontaneously induced squamous cell carcinomas by activating the epidermal growth factor receptor pathway," said senior author Yinling Hu, Ph.D., assistant professor in M. D. Anderson's Department of Carcinogenesis at the Science Park - Research Division in Smithville, Texas. "These results provide new therapeutic targets for prevention of skin cancer."
Keratinocytes originate in the basal layer of the epidermis to replace skin cells at the surface that have been shed. As keratinocytes gradually move up through the skin layers, they differentiate and eventually form the top layer of the skin, which is composed of squamous cells. The cycle ends through terminal differentiation, in which cells lose their ability to reproduce by dividing in two. They eventually die.
Hu and colleagues reported in research last year that a reduction in IKKa expression promotes the development of chemically induced papillomas and carcinomas, which are benign and malignant tumors of the epithelium respectively. Epithelial cells make up the outer layers of skin and the inner linings of many organs, including the lungs and the gastrointestinal, reproductive and urinary tracts. Most cancers originate in organ epithelial cells. The researchers also demonstrated that an intact IKKa gene is required to suppress skin cancer development.
Downregulation of IKKa has been noted in a variety of human squamous cell carcinomas, including those of the skin, esophagus, lungs, and head and neck.
IKKa's role in maintaining skin homeostasis, or stability, had remained unclear because an appropriate mouse model was not available. To solve this problem, Bigang Liu, the first author, and colleagues generated mice with IKKa deletions in their
keratinocytes. In a series of experiments, Hu's group found evidence that IKKa functions as a sentry that monitors keratinocyte proliferation and then induces terminal differentiation. In one experiment, within a few days of birth, mutant mice had developed thickened and wrinkled skin and gradually showed retarded development. The researchers also found that even a low level of IKKa in the epidermis was sufficient to allow normal embryonic skin development.
The researchers examined the signaling pathways involved in overproliferation and reduced differentiation in IKKa -deficient cells. In one, they found that IKKa turns down a cellular signaling loop that activates EGFR and other growth factors previously found to regulate keratinocyte proliferation and differentiation.
Another experiment demonstrated that IKKa deletions in keratinocytes cause skin carcinomas and that inactivating EGFR reverses this process in the mutant mice. Furthermore, either inactivation of EGFR or reintroduction of IKKa inhibited excessive cell division, induced terminal differentiation, and prevented skin cancer by repressing the EGFR-driven signaling loop.
Hu's group concluded that IKKa is a switch for proliferation and differentiation and is essential to maintaining skin homeostasis, or stability, and preventing skin cancer.
"This study has revealed the importance of IKKa in maintaining skin homeostasis and in preventing skin cancer, as well as the mechanism of how IKKa acts in these processes," Hu said. "We will further investigate how IKKa deletion targets a single cancer initiation cell, which will provide new avenues to treat cancer."
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Rare Type Of Skin Cancer Put Into Remission With New Drug.
Abnormality In KIT Gene Can Trigger Mucosal Melanoma (Yahoo News-22/07/2008)
According to the Mayo Clinic, melanoma is the most serious type of skin cancer. It develops in the cells that produce melanin, the pigment that gives your skin its color. Melanoma can also form in your eyes and in internal organs, like your intestines.
The exact cause of all melanomas isn't known, but exposure to ultraviolet (UV) radiation from sunlight or tanning lamps and beds greatly increases your risk of developing melanoma. Avoiding excessive sun exposure can prevent many melanomas and making sure you know the warning signs of skin cancer can help ensure that cancerous changes are detected and treated before they have a chance to spread. Melanoma can be successfully treated if you catch it early.
There is a simple acronym that can help patients identify dangerous moles and skin irregularities … the ABC's of skin cancer:
A -- Asymmetry: Asymmetry can be assessed by comparing one half of the growth to the other half to determine if the halves are equal in size. Unequal or asymmetric moles are suspicious.
B -- Border: If the mole's border is irregular, notched, scalloped, or indistinct, it is more likely to be cancerous (or precancerous) and is thus suspicious.
C -- Color: Variation of color within a mole is a suspicious finding. Different shades of browns, blues, reds, whites, and blacks are all concerning.
D -- Diameter: Any mole that has a diameter larger than a pencil's eraser in size should be considered suspicious.
E -- Elevation: If a mole is elevated, or raised from of the skin, it should be considered suspicious.
Melanomas do not only occur on highly visible skin. They may also arise in the lining the nose, mouth, female genitalia, anus, urinary tract and esophagus. This type of cancer is associated with the KIT gene.
Researchers discovered several different kinds of DNA abnormalities can occur on the gene, leading to different kinds of acral and mucosal melanomas -- both highly malignant forms of skin cancer. While these melanomas are relatively rare, they tend to be well advanced when diagnosed, probably because the mucosal tissues are usually out of sight and infrequently self-examined or impossible to examine easily.
Acral melanomas can be found on the palms of hands, the soles of feet and under nails while mucosal melanomas are found in the mucous membranes of the body.
A drug used to treat other types of cancer called Gleevec (imatinib mesylate) works by going in and essentially shutting off the KIT gene and specific proteins in cancer cells that cause those cells to grow and multiply.
Because Gleevec works directly with the gene, it has successfully treated mucosal and acral melanoma in preliminary trials. An understanding of the KIT gene and how it works could lead to treatment breakthroughs for other types of more common melanomas.
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Thickness, Location Predict Skin Cancer's Spread
(HealthDay News-8/07/2008)
The thicker the skin cancer tumor, the more likely it will spread or recur, according to a newly published study.
German research in the August edition of The Lancet Oncology, found that cutaneous squamous-cell carcinomas of increased tumor thickness were almost five times more likely to spread, compared to thinner lesions.
A suppressed immune system also quadrupled the likelihood of the cancer spreading, say the team from Eberhard Karls University, in Tubingen. They also found that tumors located at the ear were almost four times more likely to spread compared to tumors located elsewhere. Finally, increased horizontal size more than doubled the odds of the cancer spreading or reoccurring, the researchers report.
The study looked at 615 patients who had surgery for this most common form of skin cancer between 1990 and 2001 at a single Germany site. They found that those with tumors 2.0 millimeters or less in thickness did not have the cancer metastasize. Four percent of those with tumors between 2.1 and 6.0 millimeters thick had metastases, while 16 percent with tumors more than than 6.0 millimeters thick also did.
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Gene screening could predict your skin cancer risk(NewScientist.com
News-18/05/2008)
Most people with pale skin, red hair or freckles know to slather on extra sun block to ward off skin cancer. A trio of new studies reinforces that notion – but also suggests that genes, not pigmentation, may provide the ultimate guide to who is most likely to get skin cancer after sitting in the sun.
Researchers in Iceland and Australia studying thousands of people with melanoma and other skin cancers have pinpointed a gene affecting both a person's skin tone and their chances of getting skin cancer.
But extra rays and pale skin may not be the only explanation for the genetic link to skin cancer, says Karí Stefánnson, CEO of DeCODE Genetics in Reykjavik, Iceland. His team identified a mutation in a gene called ASIP that doubles the risk of melanoma in sun-starved Icelanders.
Freckle genes
Dermatologists have long known that being born with pale skin and light hair ups a person's chances of developing skin cancers like melanoma, presumably because less pigment offers less protection from damaging ultraviolet rays. Genetic studies have reinforced this – for instance, the same mutations in a gene called MC1R that cause red hair and freckles also greatly increase the chance of getting melanoma.
To hunt for additional genes affecting skin colour and cancer, Stefánnson's team scoured the genomes of tens of thousands of blondes, redheads, cancer patients and healthy people from Iceland, Sweden and Eastern Europe.
His team found that two mutations in the gene ASIP were tightly linked to red hair, freckles and sun sensitivity. The same mutations doubled the chances of developing melanoma, the deadliest form of skin cancer.However, sun exposure also seems to be part of the explanation. The MC1R gene is strongly linked to fair skin and cancer in Caucasians, but Stefánnson's team found it had little effect above the Arctic. "In Iceland you can avoid sunlight because it is so rare," he says.
Risk factor
"It doesn't look like it's just pigmentation," agrees geneticist Stuart MacGregor, of Queensland Institute of Medical Research in Brisbane, Australia. He led an independent team that found the same link to ASIP among melanoma patients from Queensland, which has one of the world’s highest rates of skin cancer.
MacGregor says identifying people at risk of melanoma early on, based on their genes as well as their complexions, could save lives. "Looking at just skin colour will only take you so far," he says.
Jonathan Rees, a skin cancer expert at the University of Edinburgh in Scotland says that any gene affecting complexion is almost certain to play a role in skin cancer, as well. "It is an open question whether genes will provide better markers of risk than good measures of skin colour," he says. "I am a
sceptic."
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Sunburnt Holiday-makers Boost Their Chances Of Fatal Skin Cancer
(Yahoo News-08/04/2007)
One third of young British holiday-makers will double their chances of developing the most fatal form of skin cancer this summer because they plan to get burnt on the beach.
A national survey* by Cancer Research UK, to launch its 2007 SunSmart campaign, found that 30 per cent of 16-24 year olds said they were certain to get sunburnt on their summer holiday. And a further 30 per cent said they might get
sunburnt. The survey questioned 2000 men and women of all ages throughout Britain about their sunbathing habits.
Overall more than a quarter of adults (27 per cent) thought getting burnt was all part of getting a tan. Almost one fifth (19 percent) said they planned to get burnt and a further 21 per cent said they might.
Scientists know that malignant melanoma - the potentially fatal form of skin cancer - is linked to short intense bursts of over-exposure to the sun. And research has shown that sunburn doubles the risk of skin
cancer.**
Dr Lesley Rhodes, a Cancer Research UK dermatologist, said: "Getting sunburnt increases the risk of skin cancer in general. But the kind of sunbathing binges that happen when people go to much hotter climates and bake on the beach is particularly dangerous.
"This kind of short intense exposure to the sun, leading to burning, particularly increases the risk of malignant melanoma. And each year in Britain almost 2000 people die from this form of skin cancer."
Dr Rhodes added that it was particularly worrying that more than a quarter of people surveyed believed burning was all part of getting a tan. "Rates of melanoma are set to treble in the next thirty years unless there is a radical change of behaviour among holiday makers addicted to sunbathing."
Teresa Hughes, a 53-year-old mother of two from Bedfordshire, has undergone surgery to reconstruct the side of her nose after she was diagnosed with both malignant melanoma on her cheek and non melanoma skin cancer on her nose.
She said: "I was left with a hole the size of a 10 pence piece on the side of my nose. My doctor confirmed that the cancer was caused by too much sunbathing without proper protection.
"When I was young I used to live for my holidays in the sun. But that's all over now. It is so easy to protect your skin in the sun and if talking about my experience encourages people to take better care and avoid the risk of skin cancer it will have been worthwhile."
Dr Rhodes advises that anyone with an unusual skin blemish or a mole that starts to change should get it checked out by the doctor.
"Signs to watch out for include a mole getting bigger, a mole with a ragged outline or one with a mixture of different shades of brown and black," she said. "If a mole gets inflamed or starts to bleed or itch, then get it checked out. But it's also important to remember that any of these signs don't necessarily mean you have melanoma."
SunSmart campaign manager Rebecca Russell, said: "This year the campaign is focusing on holiday-makers because research has shown that people are most likely to burn in the sun when they are on holiday.
"We want to raise awareness of the danger of burning - especially when people take off for holidays in warmer countries where the temptation to spend too long on the beach can be great.
"But it is not just a problem for those who go abroad. People, especially those with fair skin, lots of moles or freckles or a family history of skin cancer, can be at risk of burning on hot summer days in the UK."
* The survey by BMRB Omnibus was conducted by telephone, between February 2-11, 2007, among 2000 adults aged 16 plus. Results were weighted to make them nationally representative.
** Research says that sunburn doubles the risk of melanoma. (References: Gandini et al. 2005 "Meta-analysis of risk factors for cutaneous melanoma II: Sun exposure"; Elwood & Jopson 1997 "Melanoma and sun exposure: an overview of published studies".)
Skin cancers are common and 9 out of 10 of them are non-melanoma skin cancers. Many are easily treatable but others may require complex surgery and can cause some disfigurement. There are more than 67,000 new cases registered each year in the UK.
Malignant melanoma, which accounts for less than one in ten skin cancers, is the most serious type of the disease and may be fatal. It is more common in women than men but more men die from the disease.
Around 8,000 people a year in the UK are diagnosed with malignant melanoma. It usually develops in cells in the outer layer of the skin but can spread to other parts of the body. There are almost 2000 deaths each year from malignant melanoma.
Melanoma is the second most common cancer among people aged 20-39 and early detection is crucial for successful treatment.
Who is at Risk?
Some people have a greater risk of skin cancer. These people tend to:
-- burn easily
-- have fair skin and/or freckles
-- have red or fair hair and/or pale eyes
-- have had skin cancer before
-- have a large number of moles (50+)
-- have skin cancer in the family (especially melanoma)
-- have had bad sunburn in the past.
If one or more of the descriptions on this list apply to you, you should take extra care to protect yourself from the sun. Know your skin type and use the UV Index to find out when you need to protect yourself.
Babies and children need extra protection from the sun because their skin is delicate and easily damaged.
The SunSmart Messages:
-- Spend time in the shade between 11 and 3. The summer sun is most damaging to your skin in the middle of the day.
-- Make sure you never burn; sunburn can double your risk of skin cancer.
-- Aim to cover up with a t-shirt, hat and sunglasses. When the sun is at its peak sunscreen is not enough.
-- Remember to take extra care with children. Young skin is delicate. Keep babies out of the sun especially around midday.
-- Then use factor 15+ sunscreen.
-- Apply sunscreen generously and reapply often.
-- ….Also report mole changes or unusual skin growths promptly to your doctor.
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Research on worst skin cancer struggling (AP Medical Writer - 8/04/2008)
The deadliest form of skin cancer is a little-studied type you've probably never heard of. After
he died, Martin Whatley's classic rock 'n' roll guitar became his last weapon against it.
Whatley's frustrated widow carefully pulled the pristine 1964 Fender Stratocaster from under
their bed and put it up for auction on eBay, pledging half the proceeds for Merkel cell
carcinoma research and the rest to pay his medical bills. She knew scientists were having little
luck finding money to study a killer so rare that few doctors recognize it, much less know how
to treat it. "It's one thing to give a donation. But I was thinking if I did it on
eBay, so many people saw eBay, maybe it would make some people out there think about bumps that they
had," and seek help sooner, says Dana Martin Whatley of Austin, Texas. (Yes, husband and
wife shared the name Martin). She wound up donating $15,000 last year to the University of
Washington — not where her husband was treated, but where Merkel cell authority Dr. Paul
Nghiem is struggling to collect samples of patients' tumors to unravel genes that fuel the
cancer. Merkel cell carcinoma provides a poignant glimpse of the desperate intersection of
research dollars and the suffering wrought by rare diseases. It's a cancer only recognized as
distinct from melanoma — even more aggressive, and needing different treatment — about 15
years ago. Diagnoses have tripled to about 1,500 a year. Here's the rub: The first sign is a
painless bump, often reddish to purple, that can resemble a benign cyst, confusing even
dermatologists about whether a biopsy's needed. But Merkel cell carcinoma spreads rapidly
once that bump appears. A third of patients die in three years, double melanoma's mortality.
Yet there have been no well-controlled studies of the best treatment. Intense radiation is key
— unlike melanoma, Merkel cell carcinoma seems unusually radiation-sensitive, says Nghiem
(pronounced Nee-ahm). There is no evidence that adding chemotherapy right away helps, and
it may even worsen patients' chances, he adds.
Only last month was the first comprehensive report on symptoms and risk factors published. It
almost exclusively hits Caucasians, over age 50, on sun-exposed skin. And while a weak
immune system greatly increases risk, most patients, puzzlingly, have normal immunity. Then
in January, University of Pittsburgh scientists announced they'd discovered a previously
unknown virus lurking inside Merkel cell tumors, a virus that just may be the cancer's trigger.
"If we'd had funding, we could have done this easily five years ago," says lead researcher Dr.
Patrick Moore. Despite earlier success discovering another cancer virus, Moore couldn't win
government money for the Merkel cell research and spent years cobbling together dollars to
do it. The next step, also so far unfunded, is to create a blood test for this "Merkel cell
polyomavirus," to see how common it is and why it only rarely harms. Indeed, for two
decades, Merkel cell research has depended on small pilot grants and family fundraising like
Whatley's, says Nghiem. Last week, he won what is believed the disease's biggest research
grant to date, $840,000 from the American Cancer Society.
Rare diseases always struggle against more common killers for funding. "There's no money
invested in finding a cure because there's no profit margin, there's so few patients," says
George Campbell of Charleston, S.C., who founded a Google-based support group for Merkel
cell patients after his 2005 diagnosis. But belt-tightening today cuts across all diseases. The
National Institutes of Health's budget has been essentially flat since 2003, which a recent
report found equal to a 13 percent drop if medical inflation is counted. One consequence: Last
year, the number of clinical trials run by NIH's premier cancer network dropped enough that
3,000 fewer patients were enrolled, says Dr. Allen Lichter of the American Society for Clinical
Oncology. Meanwhile, a small fraternity of Merkel cell patients has banded together to push
education, of doctors and the newly diagnosed — both to help them navigate the frightening
treatment maze, and to urge them to donate tumor-tissue samples to Nghiem's lab. "The time
it takes, the research, there's just not an awareness of this at all," says Keith Boyer, 72, of
Burlington, Iowa, whose Merkel cell hasn't returned since radiation two years ago.
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Simple mole could lead to skin
cancer-(Daily Herald-31/8/2007)
Throughout the summer, many of us have heard warnings about skin cancer
but decide the information really does not apply to us. That's how I used
to feel.
Then I noticed a small mole on my upper right thigh. It was dark brown and
it seemed to be getting darker. Every morning I would think about having
it checked. Finally I made an appointment at Leone Dermatology Center in
Bloomingdale. I met with Dr. Bharati Chittineni, better known as "Dr. C."
She gave me a full body check looking everywhere, even between my toes.
She agreed that the mole on my thigh did look suspicious, and quickly
removed it, tidying up the incision with a few stitches. She then looked
intently at some tiny red raised bumps on my right shoulder. I had never
noticed these. They blended right in with my freckles. Dr. C. explained
that the raised red bumps could simply be dry skin, but they might be
basal cell carcinoma. This type of cancer, unlike melanoma, rarely
metastasizes to other body parts but it can cause bone and nerve damage if
left untreated.
Dr. C. recommended some lotion for the bumps and told me to come back the
following week to have the stitches removed in my thigh. The dermatology
exam went quickly, even with the mole removal, but the thought of skin
cancer nagged at me. As a fair-skinned, light-eyed person who easily
burns, I am a prime candidate for skin cancer. My odds for skin cancer go
up even further since I was severely sunburned many times as a child and
teenager. Dr. C. called to tell me the mole was "severely atypical," but
not melanoma. I will need additional minor surgery to remove tissue that
had surrounded the mole. If I had chosen to ignore this mole, it would
have become much more dangerous, possibly spreading cancer throughout my
body. When I went back the following week to see Dr. C., the small red
bumps remained. They were biopsied and later diagnosed as basal cell
carcinoma. Not as serious as a melanoma, but they do need to be removed.
Dr. C. says everyone needs to pay attention to their skin. Dark skin is
not a guarantee against melanoma because it can appear on your palms,
under your nails, or even on the soles of your feet. Any changing mole
should be examined by a professional. If you notice scaliness, oozing,
bleeding, itchiness or pain it is time for a check up. A normal mole
should be smaller in size than a pencil eraser, symmetrical with even
edges, and even coloring. You may already know that most skin cancers are
caused by too much ultraviolet rays, but did you know even tanning beds
can cause skin cancer? According to the American Academy of Dermatology,
skin cancer is the most prevalent of all types of cancers. The academy
estimates that every year 7,700 Americans will die from melanoma. For
those of you who, like me, ignored those skin cancer warnings -- it is
time for change. Wear suntan lotion, avoid the mid-day sun, cover up when
possible, and put on your sunglasses and a hat. Make the time to go visit
your dermatologist. The doctor's visit will go quickly and you will have
peace of mind.
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Really? The Claim: Darker Skin Protects Against Skin Cancer ( ANAHAD O'CONNOR -
15/05/2007)
It is well known that people with darker skin get deeper tans and burn less quickly than other
people. But does that mean better protection against skin cancer? The answer is not clear-cut.
Although darker-skinned people face a lower risk of skin cancer, they are more likely to
develop more aggressive forms of the disease and more likely to die from it. A large part of the
problem is a false sense of security. Dark skin has higher amounts of melanin that can filter as
much as twice the amount of ultraviolet radiation as paler skin. But that protection still falls
short of what doctors recommend when using sunscreen: a skin protection factor, or SPF, of 15
or more. And because many people with dark skin believe that it provides complete immunity,
experts say, they often overlook early warning signs. A 2006 study in The Archives of Internal
Medicine looked at more than 1,500 people with melanoma. It found that whites were far less
likely to have late-stage melanoma than blacks, Hispanics, American Indians and Asians. On
average, whites also had a greater five-year survival rate (90 percent) than the others (less
than 80 percent). Another study last year in The Archives of Dermatology looked at 1,700
cases of melanoma reported in Florida over a five-year period and had similar results.
THE BOTTOM LINE
People with darker skin tones have a lower risk of skin cancer, but are more likely to die from
it.
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Hispanics
misconstrue risks of skin cancer- (
McClatchy Newspapers- 09/03/2007)
A sunburn and skin cancer study of 369 students at Killian
High School in Miami showed that white Hispanic students were less likely
to fear skin cancer than white non-Hispanic students and less likely to
protect themselves against it.
And the differences held up even when the study compared Hispanics and
non-Hispanics of the same skin tone.
It's a dangerous misconception, said Dr. Robert S. Kirsner, vice chairman
of the department of dermatology at University of Miami Medical School and
the study's senior author.
That's because another study published in June by the U.S. Centers for
Disease Control and Prevention found that Hispanics and blacks were more
likely than non-Hispanic whites to have had a sunburn in the past year.
Sunburn prevalence was:
● 35.6 percent for non-Hispanic whites.
● 45.6 percent for Hispanics.
● 50.4 percent for blacks.
"White Hispanic students have a perception they're protected, even though
they're really not," Kirsner said. And they have this perception even
though they can have a wide range of skin tones.
The study was published in the August issue of Archives of Dermatology.
Compared with white non-Hispanic students, white Hispanic students were:
● Sharply less likely to believe they had an average or above-average risk
for skin cancer, by 23.1 percent versus 39.9 percent.
● More likely to tan deeply, by 44.2 percent versus 31 percent.
● Sixty percent less likely to have heard of skin self-examination, and 70
percent less likely to know how to perform it.
● Nearly twice as likely to seldom wear sun-protective clothing.
● About twice as likely to never or rarely use sunscreen.
● More than twice as likely to have used a tanning bed in the previous
year.
In the background research for the study, Kirsner said, it was noted that
white Hispanics do have a lower rate of skin cancer than white
non-Hispanics — but are more likely to be diagnosed at a later stage.
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Vitamin D
supplements may give benefits of sun without skin cancer risk- (Yahoo
News- 08/03/2007)
It's definitely a bit of a conundrum: sunlight is the best
source of vitamin D, and vitamin D appears to have all kinds of health
benefits. But too much sun can cause skin cancer, including the most
deadly form, malignant melanoma.
So what should Canadians do? That's what a group of doctors and
researchers from across North America are trying to figure out as they
gather in Toronto this week to assess the risks and benefits of
ultraviolet radiation and the vitamin produced from exposure to the sun.
People have been confused by conflicting messages about sun exposure,
conceded Heather Logan of the Canadian Cancer Society, which organized the
conference.
"There's been mounting scientific evidence to suggest that being in the
sun unprotected - that is, not using sunscreen - may reduce your risk of
some big cancers, like breast, prostate, colorectal and non-Hodgkin's
lymphoma," said Logan, director of cancer control policy.
"But we know, based on a solid body of evidence, that exposure to
ultraviolet radiation can increase your risk of skin cancer, premature
aging and cataracts. It's not an easy situation to deal with, and what we
don't want people to do is to end up outside unprotected - to trade
cancers for cancers."
What is known is that exposing the hands and face (without sunscreen) to
sunlight for just five to 10 minutes a week, even on sunny days in winter,
will boost vitamin D levels, she said.
In summer, when UV levels are high, just 20 seconds of sun exposure allows
the body to manufacture 400 international units (IUs) of vitamin D, the
current recommended daily allowance in Canada and the United States for
many age groups, said Dr. Edward Giovannucci, a professor of epidemiology
and nutrition at the Harvard School of Public Health.
But Giovannucci was among several experts at Wednesday's sessions who
suggested the recommended daily amounts of vitamin D are likely woefully
insufficient for optimizing health.
Animal and laboratory studies have shown that vitamin D protects against
cells replicating too rapidly - uncontrolled cell growth is the hallmark
of cancer - and from spreading to other parts of the body, he said.
Vitamin D is also believed to affect the immune system, which may explain
why rates of multiple sclerosis are higher in northern countries like
Canada, especially among darker-complexioned people whose skin provides
poor absorption of sunlight.
"Throughout human history, going back tens of thousands of years, we
evolved primarily where there was a lot of sun, and then we moved up into
more northern regions," Giovannucci said in an interview at the
conference. "There was always plenty of vitamin D around and cells needed
to use this for many purposes.
"We generally make a lot less vitamin D from the sun than we used to, and
there's not much vitamin D in foods," he said, noting that the nutrient is
found naturally in cold-water fish like salmon and is added to milk.
"Cells are becoming relatively starved of the vitamin D ... and they can't
really function 100 per cent properly. At least that's the hypothesis,
that these lower levels of vitamin D may be increasing the risk of cancers
and other conditions."
So during winter months especially, Giovannucci said, people should take
vitamin D supplements, specifically the type known as D3.
"Probably 1,000 IU is a real minimum and realistically we probably need to
go up to 2,000 IUs, which is the upper limit before you worry about toxic
or adverse affects."
Reinhold Vieth, an internationally recognized expert on vitamin D, was
unequivocal about current government and medical bodies' recommendations
regarding daily doses, calling them "absurd."
For instance, the Canadian Pediatric Society suggests infants need 400 IUs
a day - while other official guidelines tell adults under 50 to take half
that amount, despite the obvious difference in physical size, said Vieth,
director of the Bone and Mineral Laboratory at Mount Sinai Hospital in
Toronto.
"I think people who advocate avoidance of sun should likewise advocate
2,000 units of vitamin D a day, or more," said Vieth, who believes 400
units daily is adequate for children under five, but anyone over that age
should boost that amount fivefold.
He said official guidelines that warn of possible hazardous toxicity from
taking too much of the fat-soluble vitamin have been "totally overblown,"
and research suggests that even 10,000 units a day would be safe for
adults.
"The bigger hazard is being phobic of it and not taking it. The rules have
to be changed."
Logan said the Canadian Cancer Society hopes to have a position statement
advising Canadians on sun exposure an vitamin D before National Sun Safety
Awareness Week at the end of May.
White Women With Skin Cancer History More Likely To Develop Melanoma
Older white women with a history of non-melanoma skin cancer are at
greater risk for developing melanoma, regardless of the amount of sun they
have been exposed to, finds a study the online journal Cancer.
"This study adds a history of the relatively favorable non-melanoma skin
cancer -- in and of itself -- to the list of known risk factors for
melanoma in both sun lovers and shade dwellers alike," said lead author
Carol A. Rosenberg, M.D., assistant professor medicine at Northwestern
University Feinberg School of Medicine.
Rosenberg is also director of Preventive Health Initiatives, a senior
attending physician at Evanston Northwestern Healthcare and a researcher
at The Robert H. Lurie Comprehensive Cancer Center of Northwestern
University.
The study found that postmenopausal, non-Hispanic white women aged 50 to
79 years with a history of non-melanoma skin cancer, such as basal cell or
squamous cell skin cancer, but no other malignancies were more than twice
as more likely to develop cutaneous melanoma over a period of 6.5 years
compared with women who had no history of non-melanoma skin cancer, no
matter how much sun exposure or other lifestyle variables they have
experienced.
"Our study further defines melanoma risk in post-menopausal women and, it
is hoped, will sensitize the medical community to this risk, serving as a
catalyst for development of new routines of follow-up and patient
assessment to facilitate earlier detection of melanoma," said Rosenberg.
"This skin surveillance imperative may serve to be lifesaving in
predisposed women," said Rosenberg.
Non-melanoma skin cancer is the most common -- yet largely undocumented --
form of cancer in the United States.
According to the American Cancer Society, more than 1.3 million cases of
non-melanoma skin cancers are diagnosed yearly.
But because these types of cancers often carry a favorable prognosis,
patients are unlikely to be questioned specifically regarding a history of
non-melanoma skin cancer during the course of a routine general physical
examination.
Melanoma is all too often a deadly disease because it is very difficult to
treat once it has spread beyond its initial site. Although melanoma
accounts for only 4 percent of all skin cancers, someone dies every hour
from melanoma in the United States.
The ACS estimates that in 2005, almost 60,000 invasive melanomas will be
diagnosed in the United States, and nearly 7,770 men and women are
expected to die from this disease.
"Regular skin checkups to reduce the incidence of this deadly skin cancer
must focus on those at high risk," Rosenberg said. "Diagnosing melanoma
early is critical to saving lives."
Results of the study highlight a need for women to talk candidly with
their doctors about their history of skin cancer.
Findings from the study further suggest that the causal pathway of the
association between non-melanoma skin cancers and melanoma in predisposed
individuals may be due to a common gene mutation, Rosenberg said.
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