-edited) There is considerable evidence that increased levels of serum and urinary estrogens are associated with an increased risk of breast cancer in postmenopausal women. The pathway by which endogenous estrogen is metabolized may also be important. Estradiol (E2) is metabolized to a major extent through estrone (E1). E1 is then metabolized through two main metabolic pathways; the 16-alpha-hydroxy pathway yields biologically active products, while the 2-hydroxy pathway yields metabolites which are essentially devoid of estrogen activity. It has been suggested that an elevated ratio of 16-alpha- hydroxylation to 2- hydroxylation as measured by the ratio of 16-alpha-- hydroxyestrone (16-alpha-OHE1) to 2-hydroxyestrone (2-OHE1) is associated with an increased risk of breast cancer. However, the epidemiologic data that address this hypothesis are sparse. Our main aim in this study is to determine whether the known differences in breast cancer risk between ethnic groups is reflected in differences in the ratio of 16-alpha-OHE1/2-OHE1 across these groups. We will study this using urine samples from female postmenopausal participants in a large multiethnic cohort study in Hawaii and Los Angeles. Our secondary aim is to study whether diet, reproductive factors and other breast cancer risk factors affect the ratio. If the ratio of 16- alpha- OHE1/2-OHE1 can predict breast cancer risk and if this ratio can be affected by dietary or other factors, then this could have significant implications for breast cancer prevention studies.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Small Research Grants (R03)
Project #
1R03CA070684-01
Application #
2114511
Study Section
Special Emphasis Panel (SRC (20))
Project Start
1995-09-30
Project End
1996-09-29
Budget Start
1995-09-30
Budget End
1996-09-29
Support Year
1
Fiscal Year
1995
Total Cost
Indirect Cost
Name
University of Southern California
Department
Public Health & Prev Medicine
Type
Schools of Medicine
DUNS #
041544081
City
Los Angeles
State
CA
Country
United States
Zip Code
90089