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Previous studies have examined the association between individual foods or nutrients, but not overall diet, and ovarian cancer risk. To account for the clustering of foods in the diet, we investigated the association between dietary patterns and risk of ovarian cancer in the prospective California Teachers Study cohort. Of 97,292 eligible women who completed the baseline dietary assessment in 1995-1996, 311 women developed epithelial ovarian cancer on or before December 31, 2004. Based on principal components analysis, 5 major dietary patterns were identified and termed plant-based, high-protein/high-fat, high-carbohydrate, ethnic, and salad-and-wine. Multivariable Cox proportional hazards regression analysis was used to estimate associations between these dietary patterns and risk of incident ovarian cancer. Most of the dietary patterns were not significantly associated with ovarian cancer risk. However, women who followed a plant-based diet had higher risk; comparing those in the top quintile of plant-based food intake with those in the lowest quintile, the relative risk of ovarian cancer was 1.65 (95% confidence interval = 1.07-2.54; Ptrend = 0.03). Associations with the 5 dietary patterns did not vary by known ovarian cancer risk factors or other behavioral or sociodemographic characteristics. Overall, our results show no convincing associations between dietary patterns and ovarian cancer risk. [ABSTRACT FROM AUTHOR]

Diet may be a modifier of smoking-related cancer risk, with protective effects of intake of fruits and vegetables and associated antioxidants found in many observational studies. We previously reported serum Beta-Cryptoxanthin levels being inversely associated with smoking-related lung cancer incidence in a cohort of Chinese men. We noted, however, that serum Beta-Cryptoxanthinn is negatively correlated with smoking. Since self-reports of smoking intensity undoubtedly contain errors, this negative correlation indicates a potential bias in assessing the effects of Beta-Cryptoxanthin, due to confounding with the unmeasured (residual) portion of cigarette exposure. We evaluated cotinine levels in pre-diagnostic spot urine samples to attempt to improve smoking assessment. We noted that urinary cotinine levels correlated significantly with cigarette consumption overall and that cotinine was strongly predictive of lung cancer risk. Urinary cotinine, however, was not as strong a predictor of lung cancer risk in current smokers as were self-reports of cigarette consumption and cotinine remained only a marginally significant predictor of lung cancer risk after adjustment for self-reports. An apparent benefit of Beta-Cryptoxanthin remained evident when including both urinary cotinine and self-reported cigarette consumption and cotinine in the statistical model. However, we conclude that cotinine measured from a single spot urine seems to have only limited value in augmenting self-reports of cigarette consumption so that, at present, the apparent protective effects of Beta-Cryptoxanthinn, as seen in our own study, should continue to be regarded as unproven. We believe that future epidemiological evaluation of the association between Beta-Cryptoxanthin (and other antioxidants) and reduced lung cancer risk must utilize improved biomarkers to augment smokers' own self-reports of smoking amount. [ABSTRACT FROM AUTHOR]