• Unraveling the Ties of Altitude, Oxygen and Lung Cancer

    From Obama care the MLM insurance scam@21:1/5 to All on Fri Jun 3 12:08:31 2016
    XPost: alt.survival, sac.politics, alt.support.stop-smoking
    XPost: alt.health

    Epidemiologists have long been puzzled by a strange pattern in
    their data: People living at higher altitudes appear less likely
    to get lung cancer.

    Associations like these can be notoriously misleading. There is,
    for instance, a strong correlation between per-capita cheese
    consumption and the number of people strangled accidentally by
    their bedsheets. Slice and dice the profusion of data, and there
    is no end to the coincidences that can arise. Some were recently
    collected in a book called “Spurious Correlations.” Year by
    year, it turns out, the number of letters making up the winning
    word for the Scripps National Spelling Bee closely tracks the
    number of people killed by venomous spiders.

    These are probably not important clues about the nature of
    reality. But the evidence for an inverse relationship between
    lung cancer and elevation has been much harder to dismiss.

    A paper published last year in the journal PeerJ plumbed the
    question to new depths and arrived at an intriguing explanation.
    The higher you live, the thinner the air, so maybe oxygen is a
    cause of lung cancer.

    Oxygen cannot compete with cigarettes, of course, but the study
    suggests that if everyone in the United States moved to the
    alpine heights of San Juan County, Colo. (population: 700),
    there would be 65,496 fewer cases of lung cancer each year.

    This idea didn’t appear out of the blue. A connection between
    lung cancer and altitude was proposed as early as 1982. Five
    years later, other researchers suggested that oxygen might be
    the reason.

    But the authors of the PeerJ paper — two doctoral students at
    the University of Pennsylvania and the University of California,
    San Francisco — have made the strongest case yet. At the
    University of Pennsylvania Medical School, the paper won last
    year’s Abramson Cancer Center prize for basic research. And in
    July it was chosen as one of PeerJ’s best papers on cancer
    biology.

    Skeptics were quick to strike back, though not very effectively.
    A would-be debunking on the Cancer Research UK website was
    quickly followed by a debunking of the debunking.

    All of the usual caveats apply. Studies like this, which compare
    whole populations, can be used only to suggest possibilities to
    be explored in future research. But the hypothesis is not as
    crazy as it may sound. Oxygen is what energizes the cells of our
    bodies. Like any fuel, it inevitably spews out waste — a
    corrosive exhaust of substances called “free radicals,” or
    “reactive oxygen species,” that can mutate DNA and nudge a cell
    closer to malignancy.

    That is not a good reason to consume antioxidant pills. While
    the logic may seem sound, there is no convincing evidence that
    these supplements add to nature’s already formidable means of
    repairing oxidative damage — and they may even disrupt some
    delicate biological balance, increasing cancer risk and speeding
    tumor growth.

    But there is no question that oxidation, so crucial to life,
    rusts our cells and can edge them closer to becoming cancerous.

    In examining the possibility that breathing itself significantly
    increases the risk of lung cancer, the authors of the paper,
    Kamen P. Simeonov and Daniel S. Himmelstein, began by
    eliminating confounding variables. Maybe younger, healthier
    people tend to live at higher altitudes, with older and weaker
    ones, including smokers, retreating to lower lands. That could
    create the illusion of a protective altitude effect, but one
    that has nothing to do with oxygen.

    The authors also took into account factors like income,
    education and race, which affect access to medical care. To
    reduce distortions caused by noisy data, the researchers
    excluded counties with large numbers of recent immigrants, who
    might have acquired cancer-causing mutations elsewhere. Also
    ruled out were places with a large number of Native Americans,
    whose cancer rates often go underreported.

    Beyond the human variables were geophysical ones. Air at higher
    altitudes may be less polluted by carcinogens. And since
    sunlight exposure is more intense, maybe the increase in vitamin
    D helps stave off lung cancer — an idea previously suggested.
    Differences in precipitation and temperature might also have
    some effect.

    These data, too, were added to the scales, along with the
    influence of radon gas and ultraviolet rays, which is greater at
    higher elevations. The frequency of obesity and diabetes, which
    are risks for many cancers, was adjusted for, along with alcohol
    use, meat consumption and other factors.

    After an examination of all these numbers for the residents of
    260 counties in the Western United States, situated from sea
    level to nearly 11,400 feet, one pattern stood out: a
    correlation between the concentration of oxygen in the air and
    the incidence of lung cancer. For each 1,000-meter rise in
    elevation, there were 7.23 fewer lung cancer cases per 100,000
    people. (The study found no similar correlations for breast,
    colon and prostate cancer.)

    That is not a good reason to inhale less deeply at sea level or
    to flee to the mountains. Wherever you live, smoking accounts
    for as much as 90 percent of lung cancer. Radon is considered a
    distant second cause. But the PeerJ study complicates things.

    For various reasons, radon levels are generally higher at higher
    altitudes, while lung cancer rates are lower. Does that mean
    radon is not so dangerous after all? Or are its bad effects
    offset by the healthy deficit of carcinogenic oxygen?

    Or maybe radon, like thinner air, protects against lung cancer.
    According to a long-debated hypothesis called hormesis, the
    earth’s low levels of natural radiation actually might reduce
    cancer risk.

    However this all shakes out, the study is a reminder that not
    all carcinogens are manufactured by chemical plants. And not all
    of them can be avoided. You can quit smoking and mitigate the
    radon in your basement. But you can’t mitigate oxygen.

    http://www.nytimes.com/2016/01/26/science/unraveling-the-ties-of- altitude-oxygen-and-lung-cancer.html?_r=1

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