Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

BACKGROUND: Experimental data from animals suggest a protective role for the pineal hormone melatonin in the etiology of breast cancer, but results from the few retrospective case-control studies that examined the association in humans have been inconsistent. To determine whether low levels of endogenous melatonin are associated with an increased risk for developing breast cancer, we conducted a prospective nested case-control study among British women. METHODS: Concentrations of 6-sulfatoxymelatonin, the main metabolite of melatonin in urine and a validated marker of circulating melatonin levels, were measured by radioimmunoassay in 24-hour urine samples collected from women shortly after enrollment in the prospective Guernsey III Study. Levels of 6-sulfatoxymelatonin were compared among 127 patients diagnosed with breast cancer during follow-up and among 353 control subjects, matched for age, recruitment date, menopausal status, and day of menstrual cycle for premenopausal women or number of years postmenopausal for postmenopausal women. Associations were examined by analyses of covariance and conditional logistic regression. All tests of statistical significance were two-sided. RESULTS: No statistically significant differences in urinary 6-sulfatoxymelatonin concentrations were observed between women who developed breast cancer and control subjects among premenopausal or postmenopausal women (P=.8 and P=.9, respectively). When data from premenopausal and postmenopausal women were combined in a multivariable analysis adjusted for potential confounders and grouped into three categories defined by 6-sulfatoxymelatonin tertiles of control subjects, the level of 6-sulfatoxymelatonin excreted was not statistically significantly associated with the risk of breast cancer (odds ratio [OR] for breast cancer = 0.95, 95% confidence interval [CI] = 0.55 to 1.65, comparing the middle category with the lowest category of 6-sulfatoxymelatonin concentration, and OR = 0.99, 95% CI = 0.58 to 1.70, comparing the highest category with the lowest category). CONCLUSION: We found no evidence that the level of melatonin is strongly associated with the risk for breast cancer.

Original publication

DOI

10.1093/jnci/djh077

Type

Journal article

Journal

J Natl Cancer Inst

Publication Date

17/03/2004

Volume

96

Pages

475 - 482

Keywords

Adult, Aged, Breast Neoplasms, Case-Control Studies, Female, Humans, Matched-Pair Analysis, Melatonin, Menopause, Middle Aged, Multivariate Analysis, Odds Ratio, Prospective Studies, Risk Assessment, Risk Factors, United Kingdom