[PHNUTR-L] Flaxseed May Prevent Growth of Prostate Cancer
fivestar at nutritionucanlivewith.com
Tue Jun 12 19:44:36 PDT 2007
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Flaxseed May Prevent Growth of Prostate Cancer
Medscape Medical News 2007. © 2007 Medscape
June 5, 2007 (Chicago) — Flaxseed supplementation significantly reduced
tumor proliferation rates in prostate cancer patients in a trial
reported here at the American Society of Clinical Oncology (ASCO) 43rd
Annual Meeting. "These results demonstrate that flaxseed may well
protect against prostate cancer growth," said lead researcher Wendy
Demark-Wahnefried, PhD, from Duke University Medical Center, in Durham,
North Carolina. "But this is just the first study," she added. "We will
need to replicate the results before we can make recommendations."
The study was highlighted in an ASCO press conference and was also
discussed at 2 overview sessions during the meeting. "It is very
provocative," commented Bruce Cheson, MD, from the Lombardi
Comprehensive Cancer Center and Georgetown University Hospital, in
Washington, DC. "There is a hint of something there," he told
journalists when moderating the press briefing.
However, all of the experts highlighting the finding emphasized that
further research is needed.
The study was funded by grants from the National Cancer Institute and
National Institutes of Health, and the flaxseed was donated by Enreco
Inc. The dose was 30 g/day, which is about 3 round tablespoons, and the
flaxseed was ground and mixed with food and drink, as "on its own it has
a mild muddy taste," Dr. Demark-Wahnefried commented. Flaxseed is one of
the richest sources of lignan, which has several activities that could
be useful in cancer, she explained. Lignan affects androgen metabolism,
has antimitotic and antioxidant activity, has an impact on the
eicosanoid milieu, and is a rich source of omega-3 fatty acids.
The researchers also investigated the role of a low-fat diet (with fat
contributing less than 20% of the total energy) in the same study. As a
result, the trial had 4 groups: placebo control, flaxseed, low-fat diet,
and the combination of low-fat diet with flaxseed. It was conducted in
161 patients scheduled for a prostatectomy, and the median age of 59
years was lower than that of the average prostate cancer patient (68
years), Dr. Demark-Wahnefried commented. Men participated in the study
for a mean duration of 30 days and then underwent surgery; the removed
tissue was sent to 2 pathologists for analysis.
A primary analysis showed a significant reduction in the mean tumor
proliferation rate in the 2 groups on flaxseed (P = .0013), and a
reduction that was not statistically significant in the group just on
the low-fat diet (P = .053). (The figures presented at the meeting are
based on reports from both pathologists and differ from the figures in
the abstract, which were from only 1 report available at the time it was
written, Dr. Demark-Wahnefried explained.)
These results suggests that the cancer cells were growing at a
significantly slower rate (roughly 30% to 40% slower) in the 2 groups
taking flaxseed than in the group on placebo or on the low-fat diet
alone, she added. The finding fits in with previous research conducted
in vitro, which showed that lignan slowed the rate of growth of prostate
cancer cells, she noted.
Mean Tumor Proliferation Rates
Flaxseed Plus Low-Fat Diet
Secondary analyses, which included prostate cancer apoptosis and
histology of benign tissue, showed no significant differences between
the groups, but the patients on the low-fat diet showed — unsurprisingly
— a significant reduction in serum cholesterol, she said.
In answer to a question from the audience, Dr. Demark-Wahnefried noted
that the greatest effect of flaxseed was seen in men with the lower
Gleason score (< 7, in 68% of the men) and hence milder disease, which
is "what you would expect." She hesitated, however, over questions about
mechanism of action behind the effect seen, noting that there was no
reduction in testosterone, which had been expected. There may be an
effect of omega-3 fatty acids on how the cancer cells stick together,
and lignan may also have antiangiogenic properties and deprive the tumor
of its blood supply, but further work is needed on the mechanisms
involved. "We also need to disentangle the effect of flaxseed from that
of the low-fat diet," she added.
"We are excited that this study showed that flaxseed is safe and
associated with a protective effect on prostate cancer," Dr.
Demark-Wahnefried said. The results are "compelling, but preliminary,"
she added, noting that her team is now planning another trial.
American Society of Clinical Oncology 43rd Annual Meeting: Abstract
1510. Presented June 3, 2007.
Kathrynne Holden, MS, RD < fivestar at nutritionucanlivewith.com >
"Ask the Parkinson Dietitian" http://www.parkinson.org/
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