Obesity, weight gain tied to prostate cancer death
January 09, 2007
NEW YORK - Excess weight
may not raise a man's risk of developing prostate cancer,
but it may make him more likely to die of the disease, researchers
reported Monday.
In a study of nearly 288,000 U.S. men, researchers
found that obese men were actually less likely
than their thinner counterparts to develop prostate cancer
during the 5-year study period.
However, the heavier a man was, the greater
his risk of dying from the disease. Dr. Margaret E. Wright
and colleagues at the National Cancer Institute report the
findings in the journal Cancer.
Past studies have come to conflicting conclusions
about the role of excess weight in prostate cancer. While
some have suggested that increased weight
is a risk factor for the disease, most have found no relationship.
The new study followed 287,760 men between
the ages of 50 and 71 starting in 1995. At the outset, the
men completed a questionnaire about their overall health,
diet and lifestyle habits, height and weight.
Over the next five years, 9,986 men were
diagnosed with prostate cancer. Severely obese men had the
lowest risk of developing the disease.
When it came to prostate cancer deaths, however,
the risk climbed in tandem with a man's weight.
Overweight men were 25 percent more likely than thin men to
die, while obese men were 46 percent more likely.
Similarly, the amount of weight a man gained
through adulthood was unrelated to his prostate cancer risk.
But greater weight gain was linked to a higher risk of death
from the disease.
According to the researchers, hormones might
help explain why excess fat would be linked to prostate cancer
death, but not development. Obesity
lowers levels of testosterone, which helps fuel prostate cancer,
so excess weight may help prevent the disease in the first
place.
On the other hand, Wright and her colleagues
explain, heavy men have higher levels of insulin-like growth
factor-1 and leptin -- two hormones that may aid the progression
of tumors. So once an overweight man develops prostate cancer,
it may be more likely to prove fatal.
The prostate cancer progression could be
added to list of health consequences of obesity
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