Diet Study Cohort Research Articles

Sleep Duration and Cancer in the NIH-AARP Diet and Health Study Cohort.

BackgroundVery few studies have examined sleep duration in relation to cancer incidence with the exception of breast cancer.MethodsWe assessed the associations between sleep duration and incidences of total and 18 site-specific cancers in the NIH-AARP Health and Diet Study cohort, with 173,327 men and 123,858 women aged 51–72 years at baseline. Self-reported sleep duration categories were assessed via questionnaire. We used multivariable Cox proportional hazards regression to estimate hazard ratios (HR) and 95% confidence intervals (CI), using 7–8 hours/night as the reference.ResultsWe observed a significantly increased risk of stomach cancer among male short sleepers (multivariable HR5-6 vs. 7–8 hours = 1.29; 95%CI: 1.05, 1.59; Ptrend = 0.03). We also observed suggestive associations in either short or long sleepers, which did not reach overall significance (Ptrend >0.05), including increased risks in male short sleepers for cancers of head and neck (HR<5vs.7-8 hours = 1.39; 95%CI:1.00–1.95), bladder (HR5-6vs.7-8 hours = 1.10; 95%CI:1.00–1.20), thyroid (HR<5 vs. 7–8 hours = 2.30; 95%CI:1.06, 5.02), Non-Hodgkin Lymphoma (NHL) (HR5-6vs.7-8 hours = 1.17; 95%CI:1.02–1.33), and myeloma (HR<5vs.7-8 hours = 2.06; 95%CI:1.20–3.51). In women, the suggestive associations include a decreased total cancer risk (HR<5vs.7-8 hours = 0.9; 95%CI:0.83–0.99) and breast cancer risk (HR<5vs.7-8 hours = 0.84; 95%CI:0.71–0.98) among short sleepers. A decreased ovarian cancer risk (HR≥ 9 vs. 7–8 hours = 0.50; 95%CI:0.26–0.97) and an increased NHL risk (HR≥ 9 vs. 7–8 hours = 1.45; 95%CI:1.00–2.11) were observed among long sleepers.ConclusionIn an older population, we observed an increased stomach cancer risk in male short sleepers and suggestive associations with short or long sleep duration for many cancer risks in both genders.

Intra- and inter-individual variability of urinary phthalate metabolite concentrations in Hmong women of reproductive age

The reproducibility of urinary phthalate metabolite concentrations has not been well characterized in non-pregnant women of reproductive age. Our primary study objectives were to describe the distribution of urinary phthalate metabolites concentrations among a population of Hmong women of reproductive age, and to evaluate intra- and inter-individual variability of phthalate metabolite concentrations. Ten phthalate metabolites were measured in first-morning urine samples collected from 45 women and 20 of their spouses, who were members of the Fox River Environment and Diet Study cohort in Green Bay, Wisconsin. Repeated first-morning urine samples were collected and analyzed from 25 women, who provided up to three samples over approximately 1 month. Measurement variability was assessed using intraclass correlations (ICCs) and surrogate category analysis. Linear mixed models were used to evaluate the associations between participant characteristics and phthalate metabolite concentrations. Nine of the 10 phthalate metabolites were detected in >80% of all analyzed samples, of which seven were detected in all samples. As a measure of reliability, ICCs were strongest for monobenzyl phthalate (0.64) and weakest for the metabolites of di(2-ethylhexyl)phthalate (DEHP) (ranging from 0.13 to 0.22). Similarly, surrogate category analysis suggested that a single urine sample characterized an average 1-month exposure with reasonable accuracy across low, medium and high tertiles for all metabolites, except the DEHP metabolites. Geometric mean concentrations of monoethyl phthalate increased with age, but patterns by education, income, body mass index, environmental tobacco smoke or season were not observed when measures were adjusted for urinary dilution. Our results suggest that the participant characteristics assessed in this study have limited influence on inter-individual variability of phthalate metabolite concentrations. With regard to intra-individual variability, our results suggest that urinary concentrations of some phthalate metabolites are more reproducible over time and are less subjected to exposure misclassification than others (e.g., metabolites of DEHP).