Although nutritional factors are thought to play a role in the etiology of over one -third of all human cancers, information about the preventive potential of specific dietary compounds is scanty. We propose herein the renewal of a large-scale cohort study that offers unique opportunities to fill such knowledge gaps. The Shanghai Women's Health Study SWHS) is a population-based cohort study of 75,049 Chinese women who were between 40 to 70 years of age at enrollment during 1997 to 2000 and lived in urban Shanghai, where intake levels of many hypothesized cancer-inhibitory dietary factors are high and diverse. Detailed information on dietary and other lifestyle factors was collected at baseline and again in a follow-up survey. Biological samples were collected from the 87.5 percent of cohort members. The cohort has been followed for cancer occurrence and deaths through linkage with the population-based Shanghai Cancer Registry and the Shanghai Vital Statistics Unit and biannual visits to all living cohort members. We propose in this 5-year renewal to extend the follow-up of this cohort for five more years and to evaluate hypotheses related to the etiology of cancers of the breast, colorectum, lung, and stomach. The primary focus of the study is to determine whether certain diets, specifically those including regular tea drinking and high intakes of folate, soy foods, allium vegetables, and crucifers, are associated with a reduced risk of cancer. We also propose to conduct nested case-control studies of breast, lung, and colorectal cancers to evaluate whether the levels of blood folate and urinary isothiocyanate and phytoestrogens are inversely associated with the risk of these cancers. These biomarkers are aggregate measures of the level of intake, absorption, and metabolism and will provide added insight in elucidating the relations of dietary factors with cancer risk. We will further evaluate in the nested case-control studies whether the effect of dietary crucifer intake and urinary isothiocyanate excretion may be modified by genotypes of the GST-family genes. Finally, we propose to re-survey of all living cohort members to obtain updated information on usual dietary intake, physical activity, and other lifestyle factors. This will enable us to refine exposure assessment and characterize and evaluate how temporal changes in exposures may influence cancer risk. Because of it size, setting, and inventory of baseline information and biological specimens, the SWHS provides an exceptional opportunity to address dietary hypotheses for cancer that cannot be adequately investigated in any other existing cohort studies. The results from this study may guide new strategies in the primary prevention of common cancer in both Western and Asian women.
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