title: Urinary isothiocyanates; glutathione S-transferase M1, T1, and P1 polymorphisms; and risk of colorectal cancer: the Multiethnic Cohort Study.
abstract: Although an association between diet, especially cruciferous vegetables, and colorectal cancer has been hypothesized, recent studies have been inconsistent with their findings. One possibility for the discrepant results is that the interaction with related genes has not generally been considered. The present study examined the associations among urinary isothiocyanates, glutathione S-transferase (GST) polymorphisms, and colorectal cancer risk in a case-control study nested within the Multiethnic Cohort Study, based in Hawaii and Los Angeles, California. We measured prediagnositic urinary isothiocyanate levels adjusted for creatinine and analyzed GSTM1, GSTT1, and GSTP1 polymorphisms in 173 cases and 313 matched controls, with biospecimens collected between 2001 and 2006. Conditional logistic regression was used to compute odds ratios and 95% confidence intervals (95% CI). A detectable amount of urinary isothiocyanates was associated with a 41% decrease in colorectal cancer risk (95% CI, 0.36-0.98). No significant, main-effect associations were seen with a homozygous deletion of the GSTM1 or GSTT1 polymorphism, or with the AG or GG genotypes for GSTP1 rs1695. There was a weak suggestion that for individuals with the GSTP1 AG or GG genotype, a detectable amount of isothiocyanates further decreases one's risk of colorectal cancer compared with those with the GSTP1 AA genotype, but the interaction term was not statistically significant (P = 0.09). This is only the second study published on the association between urinary isothiocyanates and colorectal cancer risk. The results suggest that further studies, with larger numbers, examining a possible interaction with the GSTP1 polymorphisms are warranted.
authors.affiliation: Epidemiology Program, Cancer Research Center of Hawaii, University of Hawaii, 1236 Lauhala Street, Honolulu, HI 96813, USA. mepplein@crch.hawaii.edu
authors.forename: Meira
authors.initials: M
authors.lastname: Epplein
authors.forename: Lynne R
authors.initials: LR
authors.lastname: Wilkens
authors.forename: Maarit
authors.initials: M
authors.lastname: Tiirikainen
authors.forename: Marcin
authors.initials: M
authors.lastname: Dyba
authors.forename: Fung-Lung
authors.initials: FL
authors.lastname: Chung
authors.forename: Marc T
authors.initials: MT
authors.lastname: Goodman
authors.forename: Suzanne P
authors.initials: SP
authors.lastname: Murphy
authors.forename: Brian E
authors.initials: BE
authors.lastname: Henderson
authors.forename: Laurence N
authors.initials: LN
authors.lastname: Kolonel
authors.forename: Loïc
authors.initials: L
authors.lastname: Le Marchand
mesh_terms: D000368:Aged; D000483:Alleles; D016022:Case-Control Studies; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000208:ethnology / Q000235:genetics*; D003404:Creatinine / Q000652:urine; D005260:Female; D005838:Genotype; D051549:Glutathione S-Transferase pi / Q000235:genetics*; D005982:Glutathione Transferase / Q000235:genetics*; D006801:Humans; D017879:Isothiocyanates / Q000652:urine*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D012306:Risk; D014675:Vegetables
chemical_list: D003404:Creatinine; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase; D017879:Isothiocyanates; C413545:glutathione S-transferase T1