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

Tuesday, September 23, 2014 — Poster Session III
12:00 p.m. – 2:00 p.m.	FAES Academic Center	NCI	EPIG-2

* FARE Award Winner

Authors

• M Inoue-Choi
• RR Jones
• KE Anderson
• KP Cantor
• JR Cerhan
• S Krasner
• K Robien
• PJ Weyer
• MH Ward

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 ovarian cancer risk among 28,555 postmenopausal women and 315 incident epithelial ovarian cancers (1986-2010) in the Iowa Women’s Health Study. Dietary intake was assessed using a food frequency questionnaire. Drinking water source was obtained in a 1989 follow-up survey. Nitrate-nitrogen (NO3-N) levels for Iowa public water utilities were linked to residences, and average levels were computed based on duration at the residence. We computed multivariable-adjusted hazard ratios (HR) and 95% confidence intervals (CI) using Cox proportional hazards regression. Ovarian cancer risk was 2.2 times higher (CI=1.31-3.58, ptrend=0.001) in the highest quartile (≥2.98 mg/L) compared with the lowest quartile (≤0.47 mg/L; reference) of NO3-N in public water. Risk among private well users was also elevated (HR=1.52, CI=0.92-2.51) compared with this reference group. Associations were stronger with low intake of vitamin C, which is known to inhibit NOC formation. Dietary nitrate intake was inversely associated with ovarian cancer risk (ptrend=0.01); whereas, dietary nitrite intake from processed meats increased risk (ptrend=0.05). Replication of our findings could result in a novel target for ovarian cancer risk reduction.

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