title: Urinary melatonin concentration and the risk of breast cancer in Nurses' Health Study II.
abstract: Experimental and epidemiologic data support a protective role for melatonin in breast cancer etiology, yet studies in premenopausal women are scarce. In a case-control study nested within the Nurses' Health Study II cohort, we measured the concentration of melatonin's major urinary metabolite, 6-sulfatoxymelatonin (aMT6s), in urine samples collected between 1996 and 1999 among 600 breast cancer cases and 786 matched controls. Cases were predominantly premenopausal women who were diagnosed with incident breast cancer after urine collection and before June 1, 2007. Using multivariable conditional logistic regression, we computed odds ratios and 95% confidence intervals. Melatonin levels were not significantly associated with total breast cancer risk (for the fourth (top) quartile (Q4) of aMT6s vs. the first (bottom) quartile (Q1), odds ratio (OR) = 0.91, 95% confidence interval (CI): 0.64, 1.28; Ptrend = 0.38) or risk of invasive or in situ breast cancer. Findings did not vary by body mass index, smoking status, menopausal status, or time between urine collection and diagnosis (all Pinteraction values ≥ 0.12). For example, the odds ratio for total breast cancer among women with ≤5 years between urine collection and diagnosis was 0.74 (Q4 vs. Q1; 95% CI: 0.45, 1.20; Ptrend = 0.09), and it was 1.20 (Q4 vs. Q1; 95% CI: 0.72, 1.98; Ptrend = 0.70) for women with >5 years. Our data do not support an overall association between urinary melatonin levels and breast cancer risk.
authors.forename: Susan B
authors.initials: SB
authors.lastname: Brown
authors.forename: Susan E
authors.initials: SE
authors.lastname: Hankinson
authors.forename: A Heather
authors.initials: AH
authors.lastname: Eliassen
authors.forename: Katherine W
authors.initials: KW
authors.lastname: Reeves
authors.forename: Jing
authors.initials: J
authors.lastname: Qian
authors.forename: Kathleen F
authors.initials: KF
authors.lastname: Arcaro
authors.forename: Lani R
authors.initials: LR
authors.lastname: Wegrzyn
authors.forename: Walter C
authors.initials: WC
authors.lastname: Willett
authors.forename: Eva S
authors.initials: ES
authors.lastname: Schernhammer
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000453:epidemiology / Q000652:urine*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008550:Melatonin / Q000031:analogs & derivatives* / Q000652:urine; D008875:Middle Aged; D011446:Prospective Studies; D018570:Risk Assessment; D014481:United States / Q000453:epidemiology
chemical_list: C054513:6-sulfatoxymelatonin; D008550:Melatonin
keywords: 6-sulfatoxymelatonin; breast cancer; melatonin