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Nitrate and nitrite ingestion and risk of ovarian cancer among postmenopausal women in Iowa.

ABSTRACT: Nitrate and nitrite are precursors in the endogenous formation of N-nitroso compounds (NOC), potential human carcinogens. We evaluated the association of nitrate and nitrite ingestion with postmenopausal ovarian cancer risk in the Iowa Women's Health Study. Among 28,555 postmenopausal women, we identified 315 incident epithelial ovarian cancers from 1986 to 2010. Dietary nitrate and nitrite intakes were assessed at baseline using food frequency questionnaire data. Drinking water source at home was obtained in a 1989 follow-up survey. Nitrate-nitrogen (NO3 -N) and total trihalomethane (TTHM) levels for Iowa public water utilities were linked to residences and average levels were computed based on each woman's duration at the residence. We computed multivariable-adjusted hazard ratios (HR) and 95% confidence intervals (CI) using Cox proportional hazards regression. We tested interactions of nitrate with TTHMs and dietary factors known to influence NOC formation. Ovarian cancer risk was 2.03 times higher (CI?=?1.22-3.38, ptrend ?=?0.003) in the highest quartile (?2.98 mg/L) compared with the lowest quartile (?0.47 mg/L; reference) of NO3 -N in public water, regardless of TTHM levels. Risk among private well users was also elevated (HR?=?1.53, CI?=?0.93-2.54) compared with the same reference group. Associations were stronger when vitamin C intake was

SUBMITTER: Inoue-Choi M

PROVIDER: S-EPMC4405451 | biostudies-literature | 2015 Jul

REPOSITORIES: biostudies-literature

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Nitrate and nitrite ingestion and risk of ovarian cancer among postmenopausal women in Iowa.

Inoue-Choi Maki M Jones Rena R RR Anderson Kristin E KE Cantor Kenneth P KP Cerhan James R JR Krasner Stuart S Robien Kim K Weyer Peter J PJ Ward Mary H MH

International journal of cancer 20141208 1

Nitrate and nitrite are precursors in the endogenous formation of N-nitroso compounds (NOC), potential human carcinogens. We evaluated the association of nitrate and nitrite ingestion with postmenopausal ovarian cancer risk in the Iowa Women's Health Study. Among 28,555 postmenopausal women, we identified 315 incident epithelial ovarian cancers from 1986 to 2010. Dietary nitrate and nitrite intakes were assessed at baseline using food frequency questionnaire data. Drinking water source at home w ...[more]

PMID: 25430487

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Project description:Nitrate is a drinking water contaminant arising from agricultural sources, and it is a precursor in the endogenous formation of N-nitroso compounds (NOC), which are possible bladder carcinogens.We investigated the ingestion of nitrate and nitrite from drinking water and diet and bladder cancer risk in women.We identified incident bladder cancers among a cohort of 34,708 postmenopausal women in Iowa (1986-2010). Dietary nitrate and nitrite intakes were estimated from a baseline food frequency questionnaire. Drinking water source and duration were assessed in a 1989 follow-up. For women using public water supplies (PWS) > 10 years (n = 15,577), we estimated average nitrate (NO3-N) and total trihalomethane (TTHM) levels and the number of years exceeding one-half the maximum contaminant level (NO3-N: 5 mg/L, TTHM: 40 ?g/mL) from historical monitoring data. We computed hazard ratios (HRs) and 95% confidence intervals (CIs), and assessed nitrate interactions with TTHM and with modifiers of NOC formation (smoking, vitamin C).We identified 258 bladder cancer cases, including 130 among women > 10 years at their PWS. In multivariable-adjusted models, we observed nonsignificant associations among women in the highest versus lowest quartile of average drinking water nitrate concentration (HR = 1.48; 95% CI: 0.92, 2.40; ptrend = 0.11), and we found significant associations among those exposed ? 4 years to drinking water with > 5 mg/L NO3-N (HR = 1.62; 95% CI: 1.06, 2.47; ptrend = 0.03) compared with women having 0 years of comparable exposure. TTHM adjustment had little influence on associations, and we observed no modification by vitamin C intake. Relative to a common reference group of never smokers with the lowest nitrate exposures, associations were strongest for current smokers with the highest nitrate exposures (HR = 3.67; 95% CI: 1.43, 9.38 for average water NO3-N and HR = 3.48; 95% CI: 1.20, 10.06 and ? 4 years > 5 mg/L, respectively). Dietary nitrate and nitrite intakes were not associated with bladder cancer.Long-term ingestion of elevated nitrate in drinking water was associated with an increased risk of bladder cancer among postmenopausal women. Citation: Jones RR, Weyer PJ, DellaValle CT, Inoue-Choi M, Anderson KE, Cantor KP, Krasner S, Robien K, Beane Freeman LE, Silverman DT, Ward MH. 2016. Nitrate from drinking water and diet and bladder cancer among postmenopausal women in Iowa. Environ Health Perspect 124:1751-1758;?http://dx.doi.org/10.1289/EHP191.

Project description:Several studies have assessed the relationship between sleep duration and ovarian cancer risk, but the results are conflicting. Importantly, no studies addressed the relationship between sleep disturbance or sleep quality and ovarian cancer incidence. Moreover, few studies have examined the relationships between sleep measures and subtypes of ovarian cancer. This study included 109,024 postmenopausal women ages 50-79 from the Women's Health Initiative during 1993-1998 and followed through 2018. The Cox proportional hazards model was used to estimate adjusted HRs for the associations between sleep habits and the incidence of ovarian cancer and its subtypes. No association was observed between sleep duration, sleep quality, sleep disturbance, or insomnia and risk of overall ovarian cancer, serous/nonserous, or type I/type II ovarian cancer subtype. However, compared with women with average sleep quality, women with restful or very restful sleep quality had a significantly lower risk of invasive serous subtype [HR: 0.73, 95% confidence interval (CI): 0.60-0.90] while insomnia was associated with a higher risk of invasive serous subtype (HR: 1.36, 95% CI: 1.12-1.66). Associations with insomnia differed significantly by serous and nonserous subtypes, and type I and type II subtypes (P heterogeneity = 0.001 and P heterogeneity <0.001, respectively). This study provides no evidence on association between sleep habits and overall ovarian cancer risk among postmenopausal women. However, restful or very restful sleep quality was associated with a lower risk of invasive serous ovarian cancer, and insomnia was associated with a higher risk of invasive serous ovarian cancer. Associations with insomnia differed by subtypes. PREVENTION RELEVANCE: This study shows no association between sleep duration, sleep quality, or insomnia with the risk of overall ovarian cancer among postmenopausal women. However, restful sleep quality was associated with a lower risk of invasive serous ovarian cancer, and insomnia was associated with a higher risk of invasive serous ovarian cancer.

Project description:BackgroundDisinfection byproducts (DBPs) and N-nitroso compounds (NOC), formed endogenously after nitrate ingestion, are suspected endometrial carcinogens, but epidemiological studies are limited.ObjectivesWe investigated the relationship of these exposures with endometrial cancer risk in a large prospective cohort.MethodsAmong postmenopausal women in the Iowa Women's Health Study cohort, we evaluated two major classes of DBPs, total trihalomethanes (TTHM) and five haloacetic acids (HAA5), and nitrate-nitrogen (NO3-N) in public water supplies (PWS) in relation to incident primary endometrial cancer (1986-2014). For women using their PWS >10y at enrollment (n=10,501; cases=261), we computed historical averages of annual concentrations; exposures were categorized into quantiles and when possible ≥95th percentile. We also computed years of PWS use above one-half the U.S. maximum contaminant level (>½ MCL; 40μg/L TTHM; 30μg/L HAA5; 5mg/L NO3-N). Dietary nitrate/nitrite intakes were estimated from a food frequency questionnaire. We estimated hazard ratios (HR) and 95% confidence intervals (CI) via Cox models adjusted for age, endometrial cancer risk factors [e.g., body mass index, hormone replacement therapy (HRT)], and mutually adjusted for DBPs or NO3-N. We evaluated associations for low-grade (cases=99) vs. high-grade (cases=114) type I tumors. We assessed interactions between exposures and endometrial cancer risk factors and dietary factors influencing NOC formation.ResultsHigher average concentrations of DBPs (95th percentile: TTHM ≥93μg/L, HAA5 ≥49μg/L) were associated with endometrial cancer risk (TTHM: HR95vsQ1=2.19, 95% CI: 1.41, 3.40; HAA5: HR95vsQ1=1.84, 95% CI: 1.19, 2.83; ptrend<0.01). Associations were similarly observed for women greater than median years of PWS use with levels >½ MCL, in comparison with zero years (TTHM: HR36+vs0y=1.61, 95% CI: 1.18, 2.21; HAA5: HR38+vs0y=1.85, 95% CI: 1.31, 2.62). Associations with DBPs appeared stronger for low-grade tumors (TTHM: HRQ4vsQ1=2.12, 95% CI: 1.17, 3.83; p-trend=0.008) than for high-grade tumors (TTHM: HRQ4vsQ1=1.40, 95% CI: 0.80, 2.44; p-trend=0.339), but differences were not statistically significant (p-heterogeneity=0.43). Associations with TTHM were stronger among ever HRT users than non-HRT users (p-interaction<0.01). We observed no associations with NO3-N in drinking water or diet.DiscussionWe report novel associations between the highest DBP levels and endometrial cancer for our Iowa cohort that warrant future evaluation. https://doi.org/10.1289/EHP10207.

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Nitrate and nitrite ingestion and risk of ovarian cancer among postmenopausal women in Iowa.

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Nitrate and nitrite ingestion and risk of ovarian cancer among postmenopausal women in Iowa.

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