Cancer is the second leading cause of death in postmenopausal women. Therefore, detailed investigations are warranted to identify potentially modifiable risk factors for cancer. We recruited a population-based cohort of 41,837 Iowa women aged 55-69 years to test the hypothesis that increased abdominal fat distribution, independent of body mass, is associated with increased incidence of endometrial cancer, breast cancer, and total mortality. We obtained considerable exposure data on the cohort in a baseline survey in 1986, and we are now obtaining the third year of cancer incidence and mortality data by linkage to the Iowa Health (SEER) Registry and National Death Index. In the two-year results abdominal adiposity was independently associated with increased risk of breast cancer, total mortality, and several other nonfatal cancer endpoints ascertained by self report. However, the association of abdominal adiposity with endometrial cancer risk was not independent of body mass. With the existing wealth of baseline information on this large cohort, we propose to extend follow-up for cancer incidence and mortality through eight years. Further follow-up will allow us to verify our early results and extend them to rarer neoplasms, such as cancer of the ovary and kidney, which also may be related to fat distribution. Further follow-up will let us compare cancer rates among women living on farms versus those not living on farms. Two new aims will also be undertaken: 1) a nested case-control study of families to test whether body size or shape explains the familial clustering of breast and endometrial cancer, and 2) a pilot test of the feasibility of collecting blood samples by mail for future molecular genetic studies. The proposed project will provide new information on the risk of cancer in older women. This information could be valuable in the primary prevention of disease.