title: Serum folate and prostate-specific antigen in the United States.
abstract: OBJECTIVE
  Increased evidence suggests that folate may play a significant role in cancer development. This study investigates the association between levels of serum folate and prostate-specific antigen (PSA), a biomarker for prostate cancer detection.
  
  
  METHODS
  Using data from the 2007 to 2010 National Health and Nutrition Examination Survey, a total of 3,293 men aged 40 years and older with serum PSA and folate measures were studied. Total PSA level (tPSA) and percent free/total PSA ratio (%fPSA) were major outcomes. The alternative cutpoints were used to categorize these measures as higher risks of prostate cancer (tPSA: ≥10, ≥4, and ≥2.5 ng/ml; %fPSA: ≤15 and ≤5 %). Serum folate level was analyzed as continuous and as quintiles. Association between serum folate and PSA levels were evaluated by multivariate linear and logistic regressions.
  
  
  RESULTS
  Higher serum folate levels were associated with decreased log10-transformed tPSA (β = -001, p = 0.061) and increased %fPSA (β = 0.064, p = 0.012). Adjusting for age, race/ethnicity, socioeconomic status, use of non-steroidal anti-inflammatory drugs, body mass index, and smoking status, higher serum folate (fifth quintile) was associated with lower odds of having higher tPSA (≥10 ng/ml) and lower %fPSA (≤25 %): (tPSA: odds ratio, OR associated with fifth to first quintile of folate level = 0.42; 95 % confidence interval, CI = 0.21, 0.83; p for trend = 0.022 and %fPSA: OR = 0.71; 95 % CI = 0.52, 0.95; p for trend = 0.044).
  
  
  CONCLUSIONS
  Results of this study suggest that higher folate status may be protective against elevated PSA levels among men without diagnosed prostate cancer. Additional epidemiologic studies are necessary to confirm our findings and to investigate potential mechanisms.
authors.affiliation: Department of Pediatrics, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, USA. hany2@upmc.edu
authors.forename: Yueh-Ying
authors.initials: YY
authors.lastname: Han
authors.forename: Ji Young
authors.initials: JY
authors.lastname: Song
authors.forename: Evelyn O
authors.initials: EO
authors.lastname: Talbott
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood*; D003430:Cross-Sectional Studies; D005492:Folic Acid / Q000097:blood*; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D011379:Prognosis; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood / Q000517:prevention & control*; D014481:United States
chemical_list: D014408:Biomarkers, Tumor; D005492:Folic Acid; D017430:Prostate-Specific Antigen