THE "NEW" PROSTATE CANCER INFOLINK

Dietary factors are believed to influence the development and progression of prostate cancer. Data has now been published to show that “flaxseed is … associated with biological alterations that may be protective for prostate cancer.”

Demark-Wahnefried et al. have reported the results of a randomized, controlled, multi-center, Phase II trial to test the effects of low-fat and/or flaxseed-supplemented diets on the biology of the prostate and other biomarkers.

A total of 161 prostate cancer patients who were scheduled for prostatectomy were randomly assigned to one of the following arms of the tial for at least 21 days prior to their surgery:

• A control arm (usual diet)
• A flaxseed-supplemented diet (30 g/d)
• A low-fat diet (< 20 percent total energy)
• A flaxseed-supplemented, low-fat diet.

The patients’ blood was drawn at baseline and just before surgery and was analyzed for a range of proven and potentially relevant markers, including:

• Prostate-specific antigen (PSA)
• Sex hormone-binding globulin
• Testosterone
• Insulin-like growth factor-I (IGF-1) and binding protein-3
• C-reactive protein (CRP)
• Total and low-density lipoprotein cholesterol.

Tumors were also assessed for proliferation (Ki-67, the primary endpoint) and apoptosis.

The results documented by the authors are as follows:

• Men were on protocol an average of 30 days.
• Proliferation rates were significantly lower (P < 0.002) among men assigned to the two flaxseed-containing arms of the trial.
  • Median Ki-67-positive cells/total nuclei ratios (x100) were 1.66 for the flaxseed-supplemented diet and 1.50 for the flaxseed-supplemented, low-fat diet versus 3.23 for the control diet and 2.56 for the low-fat diet.
• No differences were observed between arms with regard to side effects, apoptosis, and most serologic endpoints.
• Men on low-fat diets experienced significant decreases in serum cholesterol (P = 0.048).

Let’s first be clear what this trial has not told us. It does not prove that supplementing your diet with flaxseed will either prevent or cure prostate cancer! We will need more data before we can come to anything even approaching that sort of absolute conclusion. It also does not seem to tell us that flaxseed supplements will lower PSA levels. (We think the abstract would say that if it was the case!)

On the other hand, what it does tell us is that dietary modification over relatively short periods of time can significantly impact biologic levels of at least some prostate cancer markers, just as a low-fat diet can significantly impact cholesterol levels. Stay tuned to see what the next step is in this arena.

Filed under: Management, Prevention, Risk