Estimating Reduction in Absolute Breast Cancer Risk in Individuals and Populations from Modifying Risk Factors

• Activity Number: 312
• Type: Contributed
• Date/Time: Tuesday, August 3, 2010 : 8:30 AM to 10:20 AM
• Sponsor: Section on Statistics in Epidemiology
• Author(s): Elisabetta Petracci*+ and Adriano Decarli and Domenico Palli and Giovanna Masala and David Pee and Ruth Pfeiffer and Catherine Schairer and Mitchell H. Gail
• Companies: Institute of Medical Statistics and Biometry and Institute of Medical Statistics and Biometry and Scientific Institute of Tuscany and Scientific Institute of Tuscany and Information Management Service Inc. and National Cancer Institute and Division of Cancer Epidemiology and Genetics and National Cancer Institute
• Keywords: breast cancer ; absolute risk model ; modifiable risk factors ; absolute reduction

Abstract

The proportion of disease that can be explained by known risk factors is often estimated using attributable risk. Less common is the calculation of absolute reductions in risk from reducing exposures. We developed a model to predict the absolute risk of breast cancer that includes reproductive risk factors and modifiable factors (alcohol, exercise, BMI) by combining relative risk estimates from an Italian case-control study with breast cancer incidence data from Italian cancer registries. In an independent cohort the model was well calibrated. We developed criteria to estimate the reduction in risk from lowering exposures, in individuals, in the whole population and in subsets at higher risk. The absolute reductions depended on the initial age and duration of the projection period. The percent reduction was nearly constant.Absolute reductions were slightly larger in high risk groups.