title: Urinary 6-Sulphatoxymelatonin levels and risk of breast cancer in premenopausal women: the ORDET cohort.
abstract: BACKGROUND
  Lower urinary melatonin levels are associated with a higher risk of breast cancer in postmenopausal women. Literature for premenopausal women is scant and inconsistent.
  
  
  METHODS
  In a prospective case-control study, we measured the concentration of 6-sulphatoxymelatonin (aMT6s) in the 12-hour overnight urine of 180 premenopausal women with incident breast cancer and 683 matched controls.
  
  
  RESULTS
  In logistic regression models, the multivariate odds ratio (OR) of invasive breast cancer for women in the highest quartile of total overnight aMT6s output compared with the lowest was 1.43 [95% confidence interval (CI), 0.83-2.45; P(trend) = 0.03]. Among current nonsmokers, no association was existent (OR, 1.00; 95% CI, 0.52-1.94; P(trend) = 0.29). We observed an OR of 0.68 between overnight urinary aMT6s level and breast cancer risk in women with invasive breast cancer diagnosed >2 years after urine collection and a significant inverse association in women with a breast cancer diagnosis >8 years after urine collection (OR, 0.17; 95% CI, 0.04-0.71; P(trend) = 0.01). There were no important variations in ORs by tumor stage or hormone receptor status of breast tumors.
  
  
  CONCLUSIONS
  Overall, we observed a positive association between aMT6s and risk of breast cancer. However, there was some evidence to suggest that this might be driven by the influence of subclinical disease on melatonin levels, with a possible inverse association among women diagnosed further from recruitment. Thus, the influence of lag time on the association between melatonin and breast cancer risk needs to be evaluated in further studies.
authors.affiliation: Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA. eva.schernhammer@channing.harvard.edu
authors.forename: Eva S
authors.initials: ES
authors.lastname: Schernhammer
authors.forename: Franco
authors.initials: F
authors.lastname: Berrino
authors.forename: Vittorio
authors.initials: V
authors.lastname: Krogh
authors.forename: Giorgio
authors.initials: G
authors.lastname: Secreto
authors.forename: Andrea
authors.initials: A
authors.lastname: Micheli
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Venturelli
authors.forename: Sara
authors.initials: S
authors.lastname: Grioni
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Sempos
authors.forename: Adalberto
authors.initials: A
authors.lastname: Cavalleri
authors.forename: Holger J
authors.initials: HJ
authors.lastname: Schünemann
authors.forename: Sabrina
authors.initials: S
authors.lastname: Strano
authors.forename: Paola
authors.initials: P
authors.lastname: Muti
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000652:urine; D001943:Breast Neoplasms / Q000652:urine*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008550:Melatonin / Q000031:analogs & derivatives* / Q000652:urine; D008875:Middle Aged; D017697:Premenopause / Q000652:urine; D011863:Radioimmunoassay; D012307:Risk Factors
chemical_list: D014408:Biomarkers, Tumor; C054513:6-sulfatoxymelatonin; D008550:Melatonin