Do Omega-3 Fatty Acids Raise Prostate Cancer Risk?


This week I want to report on a study that was published in the American Journal of Epidemiology by Brasky and associates.[1] They looked at the association between fatty acids and the possibility of developing low-risk or high-risk prostate cancer. The patients were part of the prostate cancer prevention trial during which blood samples were collected annually for 4 years. These were stored and frozen, and then for this study, samples were taken from years 1 and 4, when available, and combined. The analysis looked at the omega-3, omega-6, and trans-fatty acids.
Contrary to other studies, they found that higher levels of omega-3 fatty acids resulted in a greater chance of having high-grade prostate cancer, which is Gleason scores of 8, 9, and 10. They also found that patients with higher levels of trans-fatty acids were less likely to have high-grade disease.
Other studies have looked at the possible association between fatty acids and prostate cancer. Many studies have suggested that omega-3 fatty acids were protective against high-grade prostate cancer, and the opposite was true for the trans-fatty acids. The findings here were not what they expected. The question then becomes, what should we tell our patients? What should patients take away from this study? Many are taking omega-3 fatty acids for possible heart benefits.
We really need to ask, is this information reliable enough to make strong recommendations? The short answer is no. There are several limitations. First of all, this study does not prove cause and effect. The patients' intakes of omega-3 fatty acids weren't monitored and managed to see if there was any particular difference. Number 2, and very important, there was a difference in the association between fatty acids and high-grade disease for men taking finasteride. The finasteride could have been the cause and that has been debated before. It certainly is a possibility that finasteride was at the root of the higher incidence of high-grade disease. The other thing is that this was not a randomized study looking at the impact of taking omega-3 fatty acid supplements. Another problem is that they combined 2 samples, usually at years 1 and 4, but there may have been variations over the course of time that were not studied in this analysis, and small changes in the levels could have pushed patients into a different quartile during the analysis and in some way distorted the results.
What is the take-away message? Should men who are taking omega-3 fatty acids for potential heart benefits stop doing so because of the possibility of getting high-risk prostate cancer? This study does not clearly support that action. It is simply additional information that gets thrown into the pot of studies that have had very conflicting findings, and they all suffer from not being prospective randomized trials, assessing the possible impact of measuring and taking omega-3 fatty acid supplements.
We're going to continue to struggle with these types of studies and their meaning and implications. Ultimately, without a randomized study, it will be very difficult to make strong conclusions. Certainly we could design a study on the basis of this information, but at the present time, this study does not provide enough support to say that omega-3 fatty acids are going to increase a man's chance of getting diagnosed with prostate cancer.

Source: Medscape

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