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Study says, obesity linked to greater risk of prostate cancer in blacks

April 23, 2015

Researcher urges physicians to take note of findings

Blacks have a higher risk of
developing prostate cancer
than whites, and for obese
black men, their risk can quadruple
as their weight goes
up, a new study indicates.
The findings from this
large study should lead to a
redoubling of efforts to encourage
obesity prevention
among black men, said study
lead author Wendy Barrington,
an assistant professor
in the school of nursing
at the University of Washington.
“The main ‘take-home’
point for practicing physicians
is to recognize that obesity
has a different relationship
to prostate cancer risk
in African American [men]
compared to non-Hispanic
white men,” said Barrington.
Why this might be so is
“really just speculation at this
point,” Barrington noted.
“We did account for many
differences that could affect
prostate cancer risk, such as
access to care, and lifestyle
factors, such as diet and
physical activity,” she said.
“But it could also be that
there’s actually a biological
difference between African
American and non-Hispanic
white men . . . It’s something
for further research,” Barrington
added.
However, a cancer specialist
pointed out the study only
established an association
between race, obesity and
cancer, not a direct causeand-effect
relationship.
About six in 10 prostate
cancer cases occur in men
older than 65, the American
Cancer Society notes.
For reasons that remain unclear,
it has long been known
that at any age, blacks face
a greater overall risk for the
disease than other men. The
study team noted that blacks
also face the highest risk for
aggressive prostate cancer
and death.
To explore a possible connection
between obesity and
prostate cancer, investigators
analyzed data collected
between 2001 and 2011 by
the Selenium and Vitamin E
Cancer Prevention Trial.
The trial included nearly
3,400 black men and almost
22,700 white men, all cancerfree
and age 55 and up at the
start.
Medical histories were
gathered, including information
on smoking, diabetes,
family history of prostate
cancer, ethnicity, and education.
Body mass index (BMI)
was also assessed. BMI is a
calculation of body fat based
on height and weight.
A BMI of 25 and under is
considered normal. Obesity
is considered to be a BMI
of 30, while a BMI of 35 or
above is classified as severe
obesity.
Over a follow-up of roughly
5.5 years, the study found a
58 percent increased risk for
prostate cancer among blacks
compared with whites.
In terms of weight, researchers
found obesity
raised risk in blacks as weight
increased. For black men
with a BMI of 25 or less,
their risk for any prostate
cancer was up 28 percent,
while that risk jumped to
103 percent for blacks with a
BMI of 35 or more.
Obesity among black men
was also linked to greater risk
of both aggressive and nonaggressive
prostate cancer
risk.
Compared with healthyweight
black men, severely
obese blacks more faced a
122 percent increased risk
for low-grade (slow-moving)
prostate cancer. Their risk
for high-grade (fast-moving)
disease was 81 percent higher,
the study found.
Obese white men, meanwhile,
were found to face
a 33 percent higher risk for
aggressive prostate cancer
compared with normalweight
whites, and no greater
risk for slow-growing cancer.
In fact, obese whites appeared
to face a 20 percent
lower risk for slow-moving
prostate cancer, relative to
their healthy-weight peers,
the researchers reported.
Obesity prevention efforts
should address obstacles to
healthy eating — such as disparities
in accessing healthier
foods — “without blaming
the victim,” Barrington said.