Urinary 6-Sulphatoxymelatonin levels and risk of breast cancer in premenopausal women: the ORDET cohort.
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.
Schernhammer
Eva S
ES
Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA. eva.schernhammer@channing.harvard.edu
Berrino
Franco
F
Krogh
Vittorio
V
Secreto
Giorgio
G
Micheli
Andrea
A
Venturelli
Elisabetta
E
Grioni
Sara
S
Sempos
Christopher T
CT
Cavalleri
Adalberto
A
Schünemann
Holger J
HJ
Strano
Sabrina
S
Muti
Paola
P
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
D014408:Biomarkers, Tumor; C054513:6-sulfatoxymelatonin; D008550:Melatonin