title: Soy food frequency questionnaire does not correlate with baseline isoflavone levels in patients with bladder cancer.
abstract: BACKGROUND
  The isoflavone genistein, a natural soy product with receptor tyrosine kinase-inhibiting activity, as well as phytoestrogenic and other potential anticarcinogenic effects, is being studied as an anticancer agent. Since isoflavones are commonly consumed in food products containing soy proteins, a method to control for baseline isoflavone consumption is needed.
  
  
  METHODS
  HPLC was used to evaluate baseline plasma and urine concentrations of isoflavone in fifty-four participants with bladder cancer enrolled on a phase II chemoprevention study of G-2535. The soy food frequency questionnaire was used to assess participant's baseline soy intake. The association between baseline isoflavone concentrations and intakes for genistein and daidzein was assessed by the Spearman's rank correlation coefficient.
  
  
  RESULTS
  The majority of participants had no detectable genistein or daidzein in plasma at baseline. The median and range of values were 0 (0-1480) nmol/L for genistein, and 0 (0-1260) nmol/L for daidzein. In urine, the median and range of values were 91.0 (0-9030) nmol/L for genistein and 623 (0-100,000) nmol/L for daidzein. The median and range of weekly estimated genistein intake was 0 (0-236) mg/wk; the median and range of weekly estimated daidzein intake was 0 (0-114) mg/wk. There was no relationship to soy intake as measured by the food frequency questionnaire and baseline isoflavone levels in plasma or urine and the Spearman's rank correlation coefficients were not significant.
  
  
  CONCLUSIONS
  The soy food frequency questionnaire did not correlate with plasma or urine concentrations of either isoflavone.
  
  
  CONCLUSIONS
  Alternative methods for controlling for soy consumption, including measuring plasma and urine concentrations, in isoflavone chemoprevention trials should be considered.
authors.affiliation: School of Pharmacy, University of Wisconsin, Madison, WI, USA Carbone Comprehensive Cancer Center, University of Wisconsin, Madison, WI, USA jmkolesar@pharmacy.wisc.edu.
authors.forename: Jill M
authors.initials: JM
authors.lastname: Kolesar
authors.affiliation: Carbone Comprehensive Cancer Center, University of Wisconsin, Madison, WI, USA.
authors.forename: Marcia
authors.initials: M
authors.lastname: Pomplun
authors.affiliation: Carbone Comprehensive Cancer Center, University of Wisconsin, Madison, WI, USA Department of Biostatistics and Medical Informatics, University of Wisconsin, Madison, WI, USA.
authors.forename: Tom
authors.initials: T
authors.lastname: Havighurst
authors.affiliation: Carbone Comprehensive Cancer Center, University of Wisconsin, Madison, WI, USA.
authors.forename: Jeanne
authors.initials: J
authors.lastname: Stublaski
authors.affiliation: Carbone Comprehensive Cancer Center, University of Wisconsin, Madison, WI, USA.
authors.forename: Barbara
authors.initials: B
authors.lastname: Wollmer
authors.affiliation: Carbone Comprehensive Cancer Center, University of Wisconsin, Madison, WI, USA Department of Biostatistics and Medical Informatics, University of Wisconsin, Madison, WI, USA.
authors.forename: KyungMann
authors.initials: K
authors.lastname: Kim
authors.affiliation: Division of Cancer Prevention, National Cancer Institute, Bethesda, MD, USA.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Tangrea
authors.affiliation: Division of Cancer Prevention, National Cancer Institute, Bethesda, MD, USA.
authors.forename: Howard L
authors.initials: HL
authors.lastname: Parnes
authors.affiliation: Division of Cancer Prevention, National Cancer Institute, Bethesda, MD, USA.
authors.forename: Margaret G
authors.initials: MG
authors.lastname: House
authors.affiliation: Institute of Urology, Lahey Clinic Medical Center, Burlington, MA, USA.
authors.forename: Jason
authors.initials: J
authors.lastname: Gee
authors.affiliation: University of Rochester Medical Center, Rochester, NY, USA.
authors.forename: Edward
authors.initials: E
authors.lastname: Messing
authors.affiliation: Carbone Comprehensive Cancer Center, University of Wisconsin, Madison, WI, USA School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA.
authors.forename: Howard H
authors.initials: HH
authors.lastname: Bailey
mesh_terms: D000970:Antineoplastic Agents / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use / Q000652:urine; D015415:Biomarkers / Q000097:blood / Q000652:urine; D002851:Chromatography, High Pressure Liquid; D005247:Feeding Behavior; D019833:Genistein / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use / Q000652:urine; D006801:Humans; D007529:Isoflavones / Q000097:blood / Q000493:pharmacokinetics / Q000652:urine; D011237:Predictive Value of Tests; D045730:Soy Foods; D011795:Surveys and Questionnaires; D001749:Urinary Bladder Neoplasms / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy* / Q000652:urine
chemical_list: D000970:Antineoplastic Agents; D015415:Biomarkers; D007529:Isoflavones; C004742:daidzein; D019833:Genistein
keywords: Soy food frequency questionnaire; chemoprevention; isoflavones; pharmacokinetics