Shanghai Women's Health Study: Cancer Risk Reduction and Diet - A Cohort Study of Women

Wei Zheng, M.D., Ph.D., M.P.H.
Vanderbilt University Medical Center
Department of Medicine
Nashville, Tenn.
Funded since 1996

Nutritional factors are thought to play a role in the etiology of over one-third of all human cancers, yet information about the preventive potential of specific dietary compounds is scanty. The Shanghai Women's Health Study (SWHS) offers unique opportunities to fill such knowledge gaps.

The large-scale population-based cohort study includes 75,049 Chinese women who were between ages 40 to 70 years 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% 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.

This grant extends follow-up of the cohort and is to evaluate hypotheses related to the etiology of cancers of the breast, colorectum, lung, and stomach. The primary focus of the research is to determine whether certain diets are associated with a reduced risk of cancer. Specifically diets that include high intakes of:

• folate,
• soy foods,
• allium vegetables,
• crucifers, and
• regular tea drinking.

The investigators also are conducting 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. The investigators 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, the investigators will resurvey all living cohort members to obtain updated information on usual dietary intake, physical activity, and other lifestyle factors. This will enable them to refine exposure assessment and to 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.