Folic Acid And Risk Of Prostate Cancer: Results From A Randomized Clinical Trial

Main Category: Prostate / Prostate Cancer
Also Included In: Urology / Nephrology;  Cancer / Oncology;  Clinical Trials / Drug Trials
Article Date: 30 Apr 2009 - 2:00 PDT

email to a friend   printer friendly   opinions  

UroToday.com - In the March 18 issue of the Journal of the National Cancer Institute, Dr. Jane Figueiredo and colleagues reported on the relationship between folic acid and prostate cancer (CaP). Folate is important in methylation reactions and nucleotide synthesis. Concerns exist that folate may contribute to colon cancer development, and this study utilizes data from the Aspirin/Folate Polyp Prevention Study.

The study was a double blind, randomized clinical trial of aspirin and/or folic acid for the prevention of colorectal adenomas. All participants completed a risk factor questionnaire and a food frequency questionnaire. Non-fasting blood samples were collected for measuring circulating levels of folate and other B vitamins. Spearman rank correlation coefficient was used to calculate the correlation between dietary (excluding supplemental) and circulating levels of folate. Serum levels and dietary intake of folate were modeled as continuous variables adjusted for potential confounders.

A total of 643 men were eligible for analysis. The mean age was 57.4 years and only 6.4% of participants were African-American. Of the participants, 595 agreed to follow-up past 3 years and 472 continued the assigned folic acid. There was no significant difference between placebo and folic acid treatment groups for dietary folate, folic acid, plasma folate and red blood cell folate. However, men randomly assigned to folic acid supplementation had statistically significantly lower baseline plasma vitamin B12. CaP was diagnosed in 34 men in this study, with a mean Gleason score of 6.4. There was no statistically significant effect of aspirin on CaP risk, but there was a marked increase in risk in men randomly assigned to folic acid relative to the placebo group. The estimated probability of being diagnosed with CaP in the folic acid group was 9.7% over 10 years compared to 3.3% in the placebo group. The age-adjusted hazard ratio was 2.63.

Interestingly, in contrast to the direct association of folic acid supplementation with risk of CaP in the randomized analysis, there was suggestion of inverse association of CaP risk with dietary folate intake (HR=0.65) and with baseline plasma folate among participants who did not use multivitamins. The reason for this association is unknown, but might suggest that natural folates could be protective against CaP.

Figueiredo JC, Grau MV, Haile RW, Sandler RS, Summers RW, Bresalier RS, Burke CA, McKeown-Eyssen GE, Baron JA
J Natl Cancer Inst. 2009 Mar 18;101(6):432-5.
doi:10.1093/jnci/djp019

Written by UroToday.com Contributing Editor Christopher P. Evans, MD, FACS

UroToday - the only urology website with original content written by global urology key opinion leaders actively engaged in clinical practice.

To access the latest urology news releases from UroToday, go to: www.urotoday.com

Copyright © 2009 - UroToday

• Additional
• References
• Citations