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 The links between obesity and prostate cancer among different races
is complex, researchers say, but if emphasis is put on keeping
people at a healthy weight, the excess burden of this cancer among
African Americans might be reduced.
“Targeting obesity prevention among African American men may
contribute to reducing prostate cancer disparities,” said Wendy
Barrington, the study lead researcher from the University of
Washington School of Nursing and the Fred Hutchinson Cancer Research
Center in Seattle.
Barrington and her colleagues write in JAMA Oncology that African
American men are known to have the highest rate of new prostate
cancer cases in the U.S. They also have the highest proportion of
aggressive prostate cancers.
Overall, there were an estimated 233,000 new cases of prostate
cancer diagnosed in the U.S. during 2014, according to the National
Cancer Institute. There were also an estimated 29,480 deaths from
prostate cancer that year.
There is no evidence that prostate cancer risk factors like age,
smoking status or family medical history affect white and African
American men differently. But obesity is also considered a risk
factor, and it’s unknown whether that varies between races, the
researchers write.
For the new study, they used data from a previous trial that
followed the health of 3,398 African American and 22,673
non-Hispanic white men from 2001 to 2011. All were 55 years or
older.
After about six years, the researchers found 270 prostate cancer
cases among the African American men and 1,453 among white men.
Overall, the study team calculates, the African American men had a
58 percent increased risk for prostate cancer compared to white men.
When the researchers considered the participants’ body mass index
(BMI), a measure of weight relative to height, obesity was tied to
additional prostate cancer risk among African Americans, but not
among white men.
African American men of normal weight had 28 percent higher risk of
developing prostate cancer compared to white men. But for obese
African American men, that risk was 103 percent higher.
The relationship between obesity, prostate cancer and race also
differs depending on the aggressiveness of the disease, researchers
found.
For example, obesity is tied to an increased risk of aggressive
prostate cancer in both African American and white men. But for
less-aggressive cancers, obesity is linked to higher risk only for
African American men.
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The researchers can’t explain why African American men’s risk may be
influenced more by obesity than it is for white men. The next step
is to look to see if biological differences between the two groups
play a role, Barrington said.
“We really don’t know,” she said, adding that the study results also
cannot prove that losing weight changes a person’s risk of prostate
cancer.
Even with those limitations and the inability of the study to find a
reason for the increased risk among African Americans, Dr. Charles
Thomas Jr. wrote in an accompanying editorial that the findings
“provide a further rationale for weight reduction and a target BMI
for clinicians to aim for in care of African American men.”
Thomas, who is a deputy editor of the journal, is a cancer
specialist at Oregon Health and Science University in Portland.
“It’s a nice message for the public, because obesity is at the root
of so many health problems,” said Dr. Stacy Loeb, a urologist at NYU
Langone Medical Center in New York City. “There have been several
studies suggesting obesity is a risk factor for prostate cancer
particularly for African American men.”
“This could be one of the factors that are involved,” said Loeb, who
wasn’t involved with the new study. “I don’t think it definitely
answers the questions but it provides another piece of the puzzle.”
SOURCE: http://bit.ly/1FPcDQ7
http://bit.ly/1FPcEnf JAMA Oncology, online April 16, 2015.
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