Rapid Review Alert April 29, 2011
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ADVANCES
 In EPA & DHA Research
Abstract Details

Objective: To examine the associations between inflammation-related phospholipid fatty acids and the 7-year-period prevalence of prostate cancer. 

Experimental Design: In a nested case-control analysis of participants, aged 55–84 years, in the Prostate Cancer Prevention Trial during 1994–2003, cases (n=1,658) were frequency matched to controls (n=1,803) on age, treatment, and prostate cancer family history. Phospholipid fatty acids were extracted from serum, and concentrations of O-3, O-6, and trans-fatty acids (TFAs) were expressed as proportions of the total. Logistic regression models estimated odds ratios and 95% confidence intervals of associations of fatty acids with prostate cancer by grade.  

Results: No fatty acids were associated with low-grade prostate cancer risk. DHA was positively associated with high-grade disease. TFA 18:1 and TFA 18:2 were linearly and inversely associated with risk of high-grade prostate cancer.  

Authors' Conclusions: The study findings are contrary to those expected from the pro- and anti-inflammatory effects of these fatty acids and suggest a greater complexity of effects of these nutrients with regard to prostate cancer risk. 
Rapid Review Alert
Sudden cardiac death
Long-Chain Omega-3s and Prostate Cancer

Review of:
Brasky TM Till C White E Neuhouser ML Song X Goodman P Thompson IM King IB Albanes D and Kristal AR (2011). Serum phospholipid fatty acids and prostate cancer risk: Results from the Prostate Cancer Prevention Trial. Am J Epidemiol doi: 10.1093/aje/kwr027. 

What You Need To Know

  • Based on the totality of the scientific evidence, the benefits of eating fish and/or taking long-chain omega-3 supplements far outweigh the risks of developing high-grade prostate cancer. While there were 32,000 prostate cancer associated deaths last year in the U.S., the reality is that the 5-year relative survival for localized prostate cancer (“almost all cases were local stage” in the Prostate Cancer Prevention Trial) is 100% (National Cancer Institute). Compared to the 32,000 prostate cancer associated deaths, there were 616,000 heart disease associated deaths. Sub-optimal levels of EPA & DHA result in 72,000-96,000 deaths/year from heart disease (Danaei et al., 2009). Thus said, increasing long-chain omega-3s will decrease heart disease associated deaths with no impact on prostate cancer associated deaths.
  • The Prostate Cancer Prevention Trial was stopped early in June 2003 because of a clear finding that finasteride treatment reduced the incidence of prostate cancer. The current report is not from a new study, but an analysis of a case control study within the primary intervention trial. This is an epidemiological association only. It cannot be used to form any recommendations as DHA or LCPUFAs were not used as an intervention. 
  • Long-chain omega-3s are widely accepted in the scientific community as anti-inflammatory. Given that chronic inflammation has been implicated as a causative factor in a wide range of human cancers, intuitively, it doesn’t make sense that long-chain omega-3s would be cancer-causing.   
  • There were no associations found between fatty acid levels and the risk of low-grade prostate cancer. 


Study Limitations
  • The Prostate Cancer Prevention Trial did not use biopsy-determined absence of prostate cancer as an eligibility criterion, so cancers may have been present at baseline.
  • Those individuals diagnosed with high-grade prostate cancer were significantly older, heavier and likely to have been randomized to the finasteride treatment arm. When the Prostate Cancer Prevention Trial was stopped early because of a clear finding that finasteride treatment reduced the incidence of prostate cancer, those trial participants who did develop prostate cancer while taking the drug experienced a higher incidence of high-grade tumors.
  • The fatty acids were parameterized as a proportion rather than as a concentration. As the authors pointed out, when expressed as a proportion, a positive association with one fatty acid could lead to a falsely inverse association with another.
  • The majority of the subjects were Caucasian, limiting any generalizability of the results.
  • There is no biological basis for the outcome; a fact the authors note.
  • This study does not address the complex metabolism of fatty acids into their respective pro- and anti-inflammatory eicosanoids. 



Suggested Citation

Global Organization for EPA and DHA Omega-3s (2011). Long-Chain Omega-3s and Prostate Cancer [Peer commentary on the paper “Serum phospholipid fatty acids and prostate cancer risk: Results from the Prostate Cancer Prevention Trial” by Brasky TM Till C White E Neuhouser ML Song X Goodman P Thompson IM King IB Albanes D and Kristal AR. Am J Epidemiol doi: 10.1093/aje/kwr027.]. 
 
 

Reference

Danaei G, Ding EL, Mozaffarian D, Taylor B, Rehm J, et al. (2009) The Preventable Causes of Death in the United States: Comparative Risk Assessment of Dietary, Lifestyle, and Metabolic Risk Factors. PLoS Med 6(4): e1000058. doi:10.1371/journal.pmed.1000058 
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