THE LINK BETWEEN OMEGA-3 FATY ACID AND PROSTRATE CANCER

THE LINK BETWEEN OMEGA-3 FATY ACID AND INCREASED PROSTRATE CANCER, CONFIRMED.
A second large,
prospective study by scientists at Fred
Hutchinson Cancer Research Center
has confirmed the link between high
blood concentrations of omega-3 fatty
acids and an increased risk of prostate
cancer.
Published July 11 in the online edition
of the Journal of the National Cancer
Institute, the latest findings indicate
that high concentrations of EPA, DPA
and DHA -- the three anti-
inflammatory and metabolically
related fatty acids derived from fatty
fish and fish-oil supplements -- are
associated with a 71 percent increased
risk of high-grade prostate cancer. The
study also found a 44 percent
increase in the risk of low-grade
prostate cancer and an overall 43
percent increase in risk for all prostate
cancers.
The increase in risk for high-grade
prostate cancer is important because
those tumors are more likely to be
fatal.
The findings confirm a 2011 study
published by the same Fred Hutch
scientific team that reported a similar
link between high blood
concentrations of DHA and a more
than doubling of the risk for
developing high-grade prostate
cancer. The latest study also confirms
results from a large European study.
"The consistency of these findings
suggests that these fatty acids are
involved in prostate tumorigenesis
and recommendations to increase
long-chain omega-3 fatty acid intake,
in particular through
supplementation, should consider its
potential risks," the authors wrote.
"We've shown once again that use of
nutritional supplements may be
harmful," said Alan Kristal, Dr.P.H., the
paper's senior author and member of
the Fred Hutch Public Health Sciences
Division. Kristal also noted a recent
analysis published in the Journal of
the American Medical Association that
questioned the benefit of omega-3
supplementation for cardiovascular
diseases. The analysis, which
combined the data from 20 studies,
found no reduction in all-cause
mortality, heart attacks or strokes.
"What's important is that we have
been able to replicate our findings
from 2011 and we have confirmed
that marine omega-3 fatty acids play a
role in prostate cancer occurrence,"
said corresponding author Theodore
Brasky, Ph.D., a research assistant
professor at The Ohio State University
Comprehensive Cancer Center who
was a postdoctoral trainee at Fred
Hutch when the research was
conducted. "It's important to note,
however, that these results do not
address the question of whether
omega-3's play a detrimental role in
prostate cancer prognosis," he said.
Kristal said the findings in both Fred
Hutch studies were surprising
because omega-3 fatty acids are
believed to have a host of positive
health effects based on their anti-
inflammatory properties.
Inflammation plays a role in the
development and growth of many
cancers.
It is unclear from this study why high
levels of omega-3 fatty acids would
increase prostate cancer risk,
according to the authors, however the
replication of this finding in two large
studies indicates the need for further
research into possible mechanisms.
One potentially harmful effect of
omega-3 fatty acids is their
conversion into compounds that can
cause damage to cells and DNA, and
their role in immunosuppression.
Whether these effects impact cancer
risk is not known.
The difference in blood concentrations
of omega-3 fatty acids between the
lowest and highest risk groups was
about 2.5 percentage points (3.2
percent vs. 5.7 percent), which is
somewhat larger than the effect of
eating salmon twice a week, Kristal
said. The current study analyzed data
and specimens collected from men
who participated in the Selenium and
Vitamin E Cancer Prevention Trial
(SELECT), a large randomized,
placebo-controlled trial to test
whether selenium and vitamin E,
either alone or combined, reduced
prostate cancer risk. That study
showed no benefit from selenium
intake and an increase in prostate
cancers in men who took vitamin E.
The group included in the this analysis
consisted of 834 men who had been
diagnosed with incident, primary
prostate cancers (156 were high-grade
cancer) along with a comparison
group of 1,393 men selected
randomly from the 35,500 participants
in SELECT. The National Cancer
Institute and the National Center for
Complementary and Alternative
Medicine funded the research.
Also participating in the study were
additional Fred Hutch scientists and
researchers from the University of
Texas, University of California,
University of Washington, National
Cancer Institute and the Cleveland
Clinic.