[PHNUTR-L] Flaxseed May Prevent Growth of Prostate Cancer

[Kathrynne Holden]

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Flaxseed May Prevent Growth of Prostate Cancer
http://www.medscape.com/viewarticle/557753?src=mp
Zosia Chustecka

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
Control
	
Flaxseed
	
Low-Fat Diet
	
Flaxseed Plus Low-Fat Diet
3.23
	
1.66
	
2.56
	
1.55


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 >
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