Abstract B05: Multivitamin supplement use and prostate cancer aggressiveness by race in the North Carolina-Louisiana Prostate Cancer Project (PCaP)
Authors: McMahon Daria M. , Steck Susan E. , Su L. Joseph , Zhang Hongmei , Hebert James R. , Bensen Jeannette T. , Fontham Elizabeth T. H. , Mohler James L. , Arab Lenore 
Published: May 2015

Abstract
Background: Multivitamin supplement use has been associated with reduced overall cancer incidence in men in one recent trial, though associations with prostate cancer specifically have been null in the majority of previous studies. Most studies did not include a large sample of participants from different races/ethnicities with which to examine differences in effect by race. Multivitamin supplement use has been shown to differ by race/ethnicity; thus, the aim of the current study was to examine associations between multivitamin supplement use and prostate cancer aggressiveness by race.
Methods: Data from a large, case-only study of incident prostate cancer with approximate equal enrollment of African Americans and European Americans [the North Carolina-Louisiana Prostate Cancer Project (PCaP)] were utilized to examine the relationship between multivitamin supplement use and prostate cancer aggressiveness at time of diagnosis. Research subjects were classified as highly aggressive cases (n=350) if Gleason score ≥8, or PSA &gt;20ng/ml, or Gleason score ≥7 AND clinical stage T3-T4; or as the comparison group for all other cases with low or intermediate aggressive disease (n=1,720). Information about multivitamin supplement use including brand and frequency of intake one year prior to prostate cancer diagnosis was obtained from an interviewer-administered questionnaire. Multivitamin supplement use was categorized in two ways: 1) yes or no as reported use more than once per week in the previous year, or 2) by frequency as 0, 1-6, or 7 days/week. Multivariable logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (95%CI) for highly aggressive prostate cancer by multivitamin supplement use for all subjects and stratified by race with adjustment for age, education, prostate specific antigen screening history, smoking, body mass index, and energy intake.
Results: Overall, fewer men with highly aggressive prostate cancer took multivitamins one year prior to diagnosis as compared to men with low/intermediate aggressive disease (41 vs. 46%). Percent of multivitamin supplement users among African Americans was lower as compared to European Americans (36 vs. 54%, respectively). Overall, multivitamin supplement use was not associated with prostate cancer aggressiveness after adjustment for potential confounders (OR=0.98; 95%CI: 0.77-1.25 for yes vs. no reported use ≥once per week). In European Americans, a two-fold higher risk of highly aggressive prostate cancer was observed in men who consumed multivitamins one to six days per week compared to non-users (OR=2.08; 95%CI: 1.06-4.09), though there was no association among men who used multivitamins seven days per week (OR=1.13; 95%CI:0.78-1.64). There was no association between frequency of intake and prostate cancer aggressiveness among African Americans (OR=0.91; 95%CI:0.46-1.79 for one to six days per week and OR=0.76; 95%CI:0.51-1.79 for seven days per week compared to non-users).
Conclusion: African American men were less likely to report taking multivitamins prior to diagnosis than their European American counterparts. Multivitamin intake was not associated with prostate cancer aggressiveness after adjustment for important confounders, though there was a suggestion of increased risk among European American men regularly using multivitamins less than daily as compared to non-users. Future studies in this population examining specific formulations of multivitamins and individual nutrient supplement use are planned.
Funding: PCaP is carried out as a collaborative study supported by the Department of Defense contract DAMD 17-03-2-0052.
Citation Format: Daria M. McMahon, Susan E. Steck, L. Joseph Su, Hongmei Zhang, James R. Hebert, Jeannette T. Bensen, Elizabeth T. H. Fontham, James L. Mohler, Lenore Arab. Multivitamin supplement use and prostate cancer aggressiveness by race in the North Carolina-Louisiana Prostate Cancer Project (PCaP). [abstract]. In: Proceedings of the Sixth AACR Conference: The Science of Cancer Health Disparities; Dec 6–9, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2014;23(11 Suppl):Abstract nr B05. doi:10.1158/1538-7755.DISP13-B05