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Sunny lifestyles may halve prostate cancer risk

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  • Blommestein
    From Newscientist: * 05:00 15 June 2005 * NewScientist.com news service * Anna Gosline A healthy dose of daily sunshine could chop the risk of prostate
    Message 1 of 1 , Jun 20, 2005
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      From Newscientist:

      * 05:00 15 June 2005
      * NewScientist.com news service
      * Anna Gosline

      A healthy dose of daily sunshine could chop the risk of prostate
      cancer in half, suggests the largest study so far on UV exposure,
      vitamin D and prostate cancer risk.

      "Up until now the only things we knew about prostate cancer were
      things you can't change: being old, being black and living in northern
      latitudes," says Gary Schwartz at Wake Forest University in
      Winston-Salem, North Carolina, one of the research team.

      Back in 1990, Schwartz noticed that people at a high risk of prostate
      cancer were similar to people at risk for vitamin D deficiency: they
      often lived in northern latitudes, had darker skin and were old.
      Vitamin D is produced in the skin as a reaction to ultraviolet light
      and it subsequently metabolised in the liver and kidneys to form
      "active" vitamin D.

      Since then, numerous studies have unearthed a link between sunny
      lifestyles and reduced prostate cancer risk. But most researchers
      either relied on broad geographical trends or on subjects recalling
      specific memories of sun exposure. "The problem is that if you have
      disease, your recollection of things that might have affected your
      disease can be very biased," Schwartz explains.
      Sun on their faces

      So Schwartz, along with a team led by Esther John at the Northern
      California Cancer Center in Union City, attempted to measure sun
      exposure objectively. They measured skin pigmentation of 450 white men
      with cases of advanced prostate cancer and compared them with 455
      matched controls without the disease.

      The team calculated the difference in skin darkness between each
      person's forehead and their inner arm - an area that rarely sees
      sunshine. Recent research has suggested that the increased forehead
      pigmentation reflects a lifetime's worth of sun, darkening with age.

      They found that men with the darkest forehead - in relation to their
      inner arm - were 49% less likely to develop prostate cancer than those
      with the smallest increases in forehead pigmentation. Furthermore, the
      reduction in risk was even greater for those men who carried
      particularly "active" forms of the vitamin D receptor (VDR).
      Cheap and easy

      Richard Strange at Keele University, UK, also researches connections
      between prostate cancer and vitamin D. In a smaller group of British
      white men, he and his colleagues found that higher occupational sun
      exposure reduced risk. "Many of us now spend a very large part of our
      lives indoors. We don't have high enough levels of vitamin D to
      protect against certain cancers," he says. "The public health
      potential is enormous. Vitamin D is cheap and easy, either as
      supplements or as cautious exposure to UV. That's got to be good news."

      But the benefits of UV on vitamin D levels must be balanced against
      its known skin cancer risks, warns Cancer Research UK spokesperson
      Henry Scowcroft. "For most people, it usually takes just a few minutes
      of sun-exposure for your skin to make a very large amount of vitamin D
      - much less time than it takes for the skin to burn or even redden.
      But exactly how long is needed will depend on skin type, age, location
      and time of day and year."

      Schwartz advocates the use of dietary supplements, though optimal
      doses are unknown. While future controlled trials may resolve dosage
      issues, Schwartz suggests that men might as well increase vitamin D
      supplements now. "In the US there are 240,000 new cases of prostate
      cancer diagnosed each year. If you can do something that is safe and
      inexpensive, why not?"

      Journal Reference: Cancer Research (vol 65, p 5470)
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