Abstract 4463: Serum phytanic acid and prostate cancer risk: Results from a nested case-control study

Abstract

Abstract Phytanic acid is a saturated branched chain fatty acid found predominantly in red meat and dairy products, and may contribute to the elevated risks of prostate cancer associated with higher consumption of these foods. We measured phytanic acid as a percentage of total fatty acids by gas chromatography-mass spectrometry in prediagnostic blood samples from 300 prostate cancer cases and 300 matched controls, all of whom were participants in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study cohort. In addition to providing a fasting blood sample at baseline, all men completed extensive diet, lifestyle, and medical history questionnaires. Among controls, the strongest dietary correlates of serum phytanic acid were dairy fat, butter, and saturated fat (r=0.45, 0.42, and 0.40, respectively; all p-values <0.001). With the exception of lamb (r=0.18, p = 0.002), red meat intake was not significantly correlated with phytanic acid. There was no association between serum phytanic acid and risk of total or aggressive prostate cancer in multivariate logistic regression models. However, a significant interaction between phytanic acid and baseline concentrations of beta-carotene was noted in relation to advanced disease (p-interaction = 0.04). Among men with lower beta-carotene levels, serum phytanic acid was suggestively associated with elevated risks of advanced prostate cancer (odds ratios and 95% confidence intervals for increasing phytanic acid tertiles = 1.0 (referent), 1.42 (0.78-2.59), and 1.80 (0.91-3.55); p trend = 0.08) whereas the opposite relationship was noted among participants with higher beta-carotene levels (for increasing phytanic acid tertiles, odds ratios and 95% confidence intervals = 1.0 (referent), 1.03 (0.52-2.06), and 0.59 (0.30-1.17); p trend = 0.06). Our findings indicate that serum phytanic acid may be associated with increased risks of advanced prostate cancer in men with low levels of the antioxidant beta-carotene. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4463. doi:1538-7445.AM2012-4463