Urinary melatonin and risk of ovarian cancer.

PURPOSE: Melatonin has anti-carcinogenic properties, including modulation of estradiol production, cell cycle regulation, and promotion of apoptosis. Urinary melatonin has been inversely associated with breast cancer in some studies, but the association with ovarian cancer has not been investigated.

METHODS

We measured urinary 6-sulfatoxymelatonin (aMT6s) in nested ovarian cancer case-control studies in the Nurses' Health Study (NHS; n = 100 cases; 199 controls) and NHSII (n = 52 cases; 105 controls); samples were mainly from first morning voids. Controls were matched to cases on year of birth, menopause status, use of menopausal hormone therapy, and urine collection characteristics. We evaluated the association of tertiles of aMT6s, corrected for creatinine concentrations, with risk of ovarian cancer using conditional logistic regression. Models were adjusted for key ovarian cancer risk factors, and we additionally evaluated adjustment for usual sleep duration, snoring, and history of rotating night shift work.

RESULTS

aMT6s was not significantly associated with risk of ovarian cancer. In multivariable models, the odds ratio comparing the highest tertile of aMT6s to the lowest was 0.79, 95 % confidence interval (CI) 0.40-1.56 in the NHS and 2.88, and 95 % CI in the NHSII 0.97-8.52. Additional adjustment for sleep habits and night shift work had little impact on the observed results. We observed no clear association between urinary melatonin and ovarian cancer risk.

CONCLUSIONS

These results are consistent with our previous study in which we reported no association between night shift work and ovarian cancer; however, given the small sample size in our study, additional evaluation in larger studies is warranted.