title: Epithelial ovarian cancer and exposure to dietary nitrate and nitrite in the NIH-AARP Diet and Health Study.
abstract: Ovarian cancer is a leading cause of cancer death among women in the United States and it has the highest mortality rate of all gynecologic cancers. Internationally, there is a five-fold variation in incidence and mortality of ovarian cancer, which suggests a role for environmental factors, including diet. Nitrate and nitrite are found in various food items and they are precursors of N-nitroso compounds, which are known carcinogens in animal models. We evaluated dietary nitrate and nitrite intake and epithelial ovarian cancer in the National Institutes of Health (NIH)-AARP Diet and Health Study, including 151 316 women aged 50-71 years at the time of the baseline questionnaire in 1995-1996. The nitrate and nitrite intake was assessed using a 124-item validated food frequency questionnaire. Through 31 December 2006, 709 incident epithelial ovarian cancer cases with complete dietary information were identified. Using Cox proportional hazards regression to estimate hazard ratios and 95% confidence intervals (CIs), women in the highest intake quintile of dietary nitrate had a 31% increased risk (95% CI: 1.01-1.68) of epithelial ovarian cancer, compared with those in the lowest intake quintile. Although there was no association for total dietary nitrite, those in the highest intake category of animal sources of nitrite had a 34% increased risk (95% CI: 1.05-1.69) of ovarian cancer. There were no clear differences in risk by histologic subtype of ovarian cancer. Our findings suggest that a role of dietary nitrate and nitrite in ovarian cancer risk should be followed in other large cohort studies.
authors.affiliation: Occupational and Environmental Epidemiology Branch, DCEG, NCI, NIH, Rockville, Maryland 20852, USA. kilfoyb@mail.nih.gov
authors.forename: Briseis
authors.initials: B
authors.lastname: Aschebrook-Kilfoy
authors.forename: Mary H
authors.initials: MH
authors.lastname: Ward
authors.forename: Gretchen L
authors.initials: GL
authors.lastname: Gierach
authors.forename: Arthur
authors.initials: A
authors.lastname: Schatzkin
authors.forename: Albert R
authors.initials: AR
authors.lastname: Hollenbeck
authors.forename: Rashmi
authors.initials: R
authors.lastname: Sinha
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Cross
mesh_terms: D018262:Adenocarcinoma, Clear Cell / Q000139:chemically induced / Q000453:epidemiology*; D002288:Adenocarcinoma, Mucinous / Q000139:chemically induced / Q000453:epidemiology*; D000328:Adult; D000368:Aged; D004032:Diet; D004034:Diet Surveys; D016889:Endometrial Neoplasms / Q000139:chemically induced / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D009316:National Institutes of Health (U.S.); D009566:Nitrates / Q000009:adverse effects*; D009573:Nitrites / Q000009:adverse effects*; D010051:Ovarian Neoplasms / Q000139:chemically induced / Q000453:epidemiology*; D011446:Prospective Studies; D012307:Risk Factors; D014481:United States / Q000453:epidemiology
chemical_list: D009566:Nitrates; D009573:Nitrites