Serum levels of phytanic acid are associated with prostate cancer risk

BACKGROUND. Recent findings of over-expression of the AMACR gene in prostate cancer and association between sequence variants in the AMACR gene and prostate cancer risk, along with the well established findings of association between prostate cancer risk and overconsumption of dairy products and red meat, indirectly suggest that phytanic acid, which primarily comes from dietary intake of dairy and red meat and requires the AMACR enzyme for its metabolism, may be associated with prostate cancer risk. In this small case-control study, we assessed the association between phytanic acid levels and prostate cancer risk. METHODS. One hundred and four prostate cancer patients and controls were recruited in North Carolina. Serum levels of phytanic acid were measured using a gas liquid chromatography/mass spectroscopy analysis, and a food frequency questionnaire was administered to each individual to assess dietary intake. RESULTS. Three key findings are reported. First, there was a high correlation between two independent measurements of phytanic acid levels from the same individuals and the levels of phytanic acid were within the expected range, suggesting that serum levels of phytanic acid levels can be reliably measured in large epidemiological studies. Second, serum levels of phytanic acid among prostate cancer patients were significantly higher than that of unaffected controls, suggesting an association between phytanic acid and prostate cancer risk. Lastly, there was a significantly positive correlation between serum levels of phytanic acid and dietary intake of dairy and red meat servings during the year prior to the serum measurement. CONCLUSIONS. Although the results from our study suggest phytanic acid levels may be associated with prostate cancer risk, they were based on a study with a small sample size. Much larger studies are required to confirm these important findings. (c) 2005 Wiley-Liss. Inc.