Postmenopausal Breast Cancer: Obesity &amp; the Leptin Receptor
Creators: name: University Of California Office Of The President
Publisher: name: University of California Office of the President
publisherIdentifier: https://ror.org/00dmfq477
publisherIdentifierScheme: ROR
Year: 2024

description: Women who are obese at or after the time of menopause have a greater chance of developing breast cancer than women who are thinner. This may be due to higher levels of estrogen resulting from the obesity. (Obesity is defined as meaning over 30 on the Body Mass Index, BMI, which is a measure based on weight and height.) Leptin, a newly discovered hormone produced by fat cells, may also be related to breast cancer because leptin levels are related to several hormones thought to be associated with breast cancer. The proportion of women who are obese is increasing dramatically, particularly among women who have the greatest risk of breast cancer, those over the age of 50. Therefore, it is critical to gain a better understanding of factors that contribute to the development of obesity and how obesity increases breast cancer risk. 
 
 
 
 
 
 
 
 This pilot study will determine women’s body fat distribution by several methods, will measure several hormones in blood including leptin, and will identify what type of leptin receptor gene (OB-R) the women have. The leptin receptor gene is related to the body’s response to leptin; obese women do not respond to leptin, and we think the (OB-R) gene may be related to breast cancer because it appears to be related to obesity. In the pilot study, we will look at the relationships between different kinds of obesity, hormones in blood and different types of the leptin receptor gene (OB-R). Our overall objectives are to establish baseline measurements and then develop a more definitive study of the relationship between subtypes of obesity, OB-R and breast cancer risk as well as an experimental study of how exercise affects changes in body fat and hormones in women with specific types of obesity.
 
 
 
 
 
 
 
 We propose to study healthy obese postmenopausal African-American and Caucasian women who are 50 years of age or older (n=100) and who previously participated in our study of breast cancer risk factors. We already have extensive information from these women about their family history of cancers, use of oral contraceptives and other hormones, reproductive histories, and lifetime exercise history. We will ask new questions about their current medical history, family histories of diabetes and obesity, current exercise patterns, current medication usage, and diet.
 
 
 
 
 
 
 
 Participants will be invited to our physical therapy laboratory where they will complete the study questionnaire, and where we will measure their body fat distribution, and draw a blood sample that will be used to measure hormones and the OB-R gene. We will use several different methods to measure body fat including measuring skinfold thickness, calculating the waist-to-hip ratio, calculating body-mass-index based on weight and height, and DEXA scanning, a non-invasive means of measuring percent body fat. 
 
 
 
 
 
 
 
 Certain types of obesity (upper body vs. lower body) may reflect hormone levels and variations of the OB-R gene that are associated with a greater chance of developing breast cancer than others. This study will generate new information about the relationship between obesity and hormones with respect to this gene and enable us to ask more refined and specific questions about what causes breast cancer in the future and enable us to develop more focused programs for risk reduction.