Abstract PR14: Dietary folate and prostate cancer tumor aggressiveness differences between African Americans and European Americans
Authors: Aguilar Daniela Ramirez , Steck Susan E , Lin Hui-Yi , Su LJ 
Published: September 2020

Introduction: Folate is a water-soluble B vitamin, which is involved in DNA synthesis and repair and in regulation of gene expression through DNA methylation as a methyl donor. Despite the confirmed beneficial effect on the prevention of neural tube defect, concerns have been raised on high intakes of folate and its synthetic form, folic acid, may promote carcinogenesis or cancer progression. African American (AA) males tend to have a more aggressive prostate cancer tumor diagnosis compared to European American (EA) males.

Objective: This aim of this study is to examine the association between folic acid intake in the year prior to PCa diagnosis among AAs and EAs. Using a population-based case-only study, an examination of folic acid was conducted to evaluate the effects of dietary folate on prostate cancer aggressiveness.

Methods: Data from the North Carolina-Louisiana Prostate Cancer Project (PCaP) questionnaire were used to evaluate 1,497 participants (AA n = 722 and EA n = 775) with a low or high aggressiveness prostate cancer to assess dietary folate intake one year prior to PCa diagnosis using the National Cancer Institute Dietary History Questionnaire. High-aggressive disease was defined as Gleason sum ≥8, or prostate-specific antigen (PSA) &gt;20 ng/mL, or Gleason score ≥7 and clinical stage T3-T4, while low-aggressive disease was defined as Gleason sum &lt;7 and stage T1—T2 and PSA &lt;10 ng/mL. All four variables for dietary folate (natural folate, synthetic folate, folate, and dietary folates) were examined. Multivariate logistic regression was used to assess dietary folate and prostate cancer aggressiveness. Confounding variables considered for this analysis include age, BMI, total energy (kcal), education level, and first-degree family history of PCa. Additionally, dietary folate was categorized into tertiles. Models were stratified by race and the dose-response relationship was evaluated.

Results: Folate intakes, regardless natural folate (mean = 354.5 vs 304.1), synthetic folate (176.3 vs 157.5), or total dietary folate equivalent (654.0 vs 571.5), were higher among AA than EA, respectively. Based on the tertile categorization, the highest dietary folate was significantly associated with high-aggressive prostate cancer when compared to the lowest intake group among AA and EA combined (odds ratio (OR) = 1.41, 95% confidence interval (CI) = 1.04 – 1.90) after adjusted for confounders. Stratified model by race showed that there is an increased trend in PCa aggressiveness and increased folate intake (2nd tertile OR = 1.03, 95%CI = 0.67 – 1.56; 3rd tertile OR = 1.41, CI = 1.11 – 2.48), p-value for trend = 0.01. The association was not observed among EA. The trend is very similar regardless of natural or synthetic folate.

Conclusion: It appeared that AA with high folic acid intake had a greater chance of being diagnosed with high-aggressiveness PCa, while the association was not observed among EA. The finding suggests that the metabolism of folate may be different between AA and EA, possibly due to genetic polymorphisms.

This abstract is also being presented as Poster C034.

Citation Format: Daniela Ramirez Aguilar, Susan E Steck, Hui-Yi Lin, LJ Su. Dietary folate and prostate cancer tumor aggressiveness differences between African Americans and European Americans [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr PR14.