title: Lycopene intake and prostate cancer risk: effect modification by plasma antioxidants and the XRCC1 genotype.
abstract: Lycopene has been associated with reduced prostate cancer risk, although the results of epidemiological studies have varied. We hypothesize that an effect of lycopene may be modified by XRCC1 genotype and other antioxidants. We used a food-frequency questionnaire to assess lycopene intake in a case-control study of prostate cancer in North Carolina. Plasma alpha-tocopherol and beta-carotene levels were measured using high-performance liquid chromatography. XRCC1 genotypes were detected using polymerase chain reaction-restriction fragment length polymorphism. The final dataset included 77 cases and 174 controls with complete questionnaires, genotyping, and plasma analyses. Among men with the Arg/Arg genotype at codon 399, odds ratios (ORs) for prostate cancer risk associated with medium (732-1,529 microg/day) and high (>1,529 microg/day) lycopene intake were 0.59 (95% confidence interval = 0.23-1.50) and 0.21 (0.06-0.71), respectively (P(trend) < 0.01). Similar analyses for persons with Arg/Gln or Gln/Gln genotypes produced null results. Above-median (1,048 microg/day) lycopene intake combined with above-median levels of alpha-tocopherol and beta-carotene was associated with an OR of 0.11 (0.02-0.65) among men with the Arg/Arg genotype but not those with at least one Gln allele (P(interaction) = 0.01). Although limited by small sample size, these findings indicate that the association between lycopene and prostate cancer is complex and may be modified by other antioxidants and by XRCC1 genotype.
authors.affiliation: Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA. mgoodm2@sph.emory.edu
authors.forename: Michael
authors.initials: M
authors.lastname: Goodman
authors.forename: Roberd M
authors.initials: RM
authors.lastname: Bostick
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Ward
authors.forename: Paul D
authors.initials: PD
authors.lastname: Terry
authors.forename: Carla H
authors.initials: CH
authors.lastname: van Gils
authors.forename: Jack A
authors.initials: JA
authors.lastname: Taylor
authors.forename: Jack S
authors.initials: JS
authors.lastname: Mandel
mesh_terms: D000368:Aged; D016588:Anticarcinogenic Agents / Q000008:administration & dosage*; D000975:Antioxidants / Q000008:administration & dosage*; D002338:Carotenoids / Q000008:administration & dosage*; D016022:Case-Control Studies; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003062:Codon; D016001:Confidence Intervals; D004268:DNA-Binding Proteins / Q000235:genetics*; D005838:Genotype; D006801:Humans; D000077276:Lycopene; D008297:Male; D008875:Middle Aged; D009657:North Carolina / Q000453:epidemiology; D016017:Odds Ratio; D012150:Polymorphism, Restriction Fragment Length; D011471:Prostatic Neoplasms / Q000453:epidemiology* / Q000235:genetics; D012307:Risk Factors; D011795:Surveys and Questionnaires; D000076105:X-ray Repair Cross Complementing Protein 1; D024502:alpha-Tocopherol / Q000008:administration & dosage; D019207:beta Carotene / Q000008:administration & dosage
chemical_list: D016588:Anticarcinogenic Agents; D000975:Antioxidants; D003062:Codon; D004268:DNA-Binding Proteins; D000076105:X-ray Repair Cross Complementing Protein 1; C000619371:XRCC1 protein, human; D019207:beta Carotene; D002338:Carotenoids; D024502:alpha-Tocopherol; D000077276:Lycopene