Abstract 1881: Dietary, supplement, and adipose tissue tocopherol levels in relation to prostate cancer aggressiveness among African- and European-Americans

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA Background: Controversies remain over the safety and efficacy of vitamin E (α-tocopherol) supplement use for the prevention of prostate cancer (CaP); however, associations between different tocopherol forms and CaP aggressiveness have yet to be examined. This study examined whether food intake of tocopherols, vitamin E supplement use, and adipose tissue biomarkers of tocopherol were associated with CaP aggressiveness among African-American (AA) and European-American (EA) men with newly diagnosed CaP. Methods: Associations between tocopherols from diet, vitamin E supplement use, and adipose tissue tocopherol levels and CaP aggressiveness were examined in a large population-based, case-only study of incident CaP among AA (n = 1,023) and EA (n = 1,079) research subjects enrolled in the North Carolina-Louisiana Prostate Cancer Project (PCaP). CaP aggressiveness was defined by a combination of clinical Gleason sum and stage and prostate-specific antigen (PSA) level at diagnosis as high aggressive (Gleason sum ≥8 or PSA >20 ng/mL, or Gleason sum ≥ 7 and cancer stage T3-T4); low aggressive (Gleason sum < 7 and stage T1-T2 and PSA<10 ng/ml); or intermediate aggressive CaP (all others). Dietary tocopherol intake was estimated from a food frequency questionnaire, supplement use from questionnaire/inventory, and biomarkers from abdominal adipose samples measured using high-performance liquid chromatography. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95%CIs) comparing high aggressive CaP to low/intermediate aggressive CaP. Results: Higher dietary intakes of α- and δ-tocopherol were inversely and linearly associated with CaP aggressiveness among EAs [OR (95%CI), highest vs. lowest quartile: α-tocopherol 0.34 (0.17-0.69) Ptrend = 0.006; δ-tocopherol 0.45 (0.21-0.95) Ptrend = 0.007]. Dietary tocopherol levels were not associated with CaP aggressiveness among AAs. No significant associations were observed between supplemental vitamin E use and CaP aggressiveness among AAs or EAs. Mean adipose α-tocopherol concentrations were markedly higher in EAs (151.4 mcg/g) compared to AAs (86.6 mcg/g). No statistically significant associations between adipose α-tocopherol levels and high aggressive CaP were observed [OR (95%CI); highest versus lowest quartiles were for EAs 1.43 (0.66-3.11) and AAs 0.66 (0.27-1.62)]. Conclusions: These results add to the literature suggesting no obvious benefit from vitamin E supplement use in relation to CaP aggressiveness. Inverse associations between higher dietary sources of tocopherols and aggressive CaP among EAs suggest that diets high in tocopherols may contain additional protective components or may be a marker for an overall healthier lifestyle. Citation Format: Samuel Antwi, Susan E. Steck, L. Joseph Su, James R. Hebert, Hongmei Zhang, Elizabeth T. H. Fontham, Jeannette T. Bensen, James L. Mohler, Lenore Arab. Dietary, supplement, and adipose tissue tocopherol levels in relation to prostate cancer aggressiveness among African- and European-Americans. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1881. doi:10.1158/1538-7445.AM2015-1881