Urinary 6-sulfatoxymelatonin Levels and Prostate Cancer Risk among Men in the Multiethnic Cohort.

BACKGROUND: The circadian hormone melatonin has anticancer properties, and prior studies suggest a positive association between low melatonin and prostate cancer risk. The purpose of this study was to examine urinary melatonin levels and prostate cancer in a racially/ethnically diverse cohort. METHODS: We conducted a nested case-control study, including 1,263 prostate cancer cases and 2,346 controls, sampled from participants in the Multiethnic Cohort Study with prediagnostic urine samples assayed for 6-sulfatoxymelatonin, the primary melatonin metabolite. Conditional logistic regression was used to examine the association between melatonin levels and the development of prostate cancer outcomes (all incident cases, advanced, lethal, high-grade, and aggressive), overall and by race/ethnicity. RESULTS: Among 1,263 cases, 135 were advanced stage, 101 were lethal cases, and 282 were high-grade disease. Median melatonin levels were similar in controls [17.12 ng/mL; interquartile range (IQR), 19.78] and cases (17.93 ng/mL; IQR, 19.76), and we found no significant association between urinary melatonin levels and prostate cancer risk overall or in any clinical or racial subgroup. CONCLUSIONS: In this diverse cohort, there was no significant association between melatonin and any prostate cancer outcome, nor were there any differences by racial/ethnic group. IMPACT: These results do not support a strong association between melatonin levels and risk of prostate cancer.

Circulating sclerostin associated with vertebral bone marrow fat in older men but not women.

CONTEXT: Osteocyte activity is crucial to the maintenance of bone quality. Sclerostin, an osteocyte product, inhibits bone formation, yet higher circulating sclerostin is associated with higher bone density. Bone marrow fat (MF) is associated with osteoporosis, but little is known about the relationship between osteocyte activity and MF. OBJECTIVE: Our objective was to assess the relationships between circulating sclerostin, vertebral MF, volumetric bone mineral density (vBMD), and other fat depots in older adults. DESIGN, SETTING, AND PARTICIPANTS: We conducted a cross-sectional study in the Age Gene/Environment Susceptibility-Reykjavik cohort. MAIN OUTCOME MEASURES: Outcome measures included vertebral MF (L1-L4) measured with magnetic resonance spectroscopy and vBMD (spine and hip) and abdominal fat measured with quantitative computed tomography. RESULTS: After excluding subjects with bone-active medication use (n = 50), inadequate serum (n = 2), or inadequate magnetic resonance spectroscopy (n = 1), analyses included 115 men and 134 women (mean age 79 y, mean body mass index 27.7 kg/m(2)). In men, but not women, vertebral MF was greater in those with higher serum sclerostin levels. MF was 52.2 % in the lowest tertile of serum sclerostin and 56.3% in the highest tertile in men (P for trend <.01) in models adjusted for age, body mass index, and diabetes. Sclerostin was positively associated with cortical and trabecular total hip vBMD, weight in men and women, and total fat mass in men but was not associated with total lean mass or abdominal fat depots. CONCLUSION: Circulating sclerostin levels are associated with higher vertebral marrow fat in men, suggesting a relationship between osteocyte function and marrow adipogenesis.

Serum levels of marine-derived n-3 fatty acids in Icelanders, Japanese, Koreans, and Americans--a descriptive epidemiologic study.

In the 1990s Iceland and Japan were known as countries with high fish consumption whereas coronary heart disease (CHD) mortality in Iceland was high and that in Japan was low among developed countries. We described recent data fish consumption and CHD mortality from publicly available data. We also measured CHD risk factors and serum levels of marine-derived n-3 and other fatty acids from population-based samples of 1324 men in Iceland, Japan, South Korea, and the US. CHD mortality in men in Iceland was almost 3 times as high as that in Japan and South Korea. Generally, a profile of CHD risk factors in Icelanders compared to Japanese was more favorable. Serum marine-derived n-3 fatty acids in Iceland were significantly lower than in Japan and South Korea but significantly higher than in the US.