Abstract 3722: Modification of obesity effects on prostate cancer outcomes by age and education
Authors: Zeigler-Johnson Charnita M. , Morales Knashawn , Mitchell Jonathan , Spangler Elaine , Glanz Karen , Rebbeck Timothy 
Published: August 2015

Background: Poor prostate cancer (PCa) outcomes have been associated with obesity. Patient age and educational attainment may influence factors related to cancer knowledge, fear of cancer, and screening practices. The goal of this project was to determine how obesity effects on prostate cancer outcomes may be modified by age and education. The specific study aim was to examine the impact of education and age on the relationship between pre-treatment obesity and prostate cancer severity and risk of biochemical failure. The hypothesis was that the relationship between obesity and prostate cancer severity varies by demographic factors.

Methods: Our sample included 1318 Caucasian (CA) and 327 African American (AF) PCa patients in the Study for Clinical Outcomes Risk and Ethnicity at the University of Pennsylvania Health System. Obese was defined as a BMI of 30 kg/m2. Patient age was dichotomized at the median (60 years) and education was quantified as less than college degree vs. college degree. The outcomes of interest were advanced stage (T3, T4), advanced grade (Gleason score 7+) and risk of biochemical failure. Modification by age and education groups was analyzed in age-adjusted and race-stratified logistic models for stage and grade outcomes and Cox regression models for time to biochemical failure.

Results: Obese CA men were more likely to have high PCa stage (OR = 1.61, 95% CI = 1.22-2.11) and grade (OR = 1.63, 95% CI = 1.27-2.09). Effects on stage were similar regardless of age group or educational attainment. However, younger CA and AF men (OR = 1.94, 95% CI = 1.35-2.78 and OR = 2.29, 95% CI = 1.19-4.42, respectively), as well as CA men with higher education (OR = 2.01, 95% CI = 1.46-2.70) were more likely to have advanced grade at diagnosis. Time to biochemical failure was significant only among African Americans in the younger age group (HR = 3.72, 95%CI = 1.23-11.23) and with less education (HR = 3.39, 95% CI = 1.36-8.43).

Conclusions: The results suggested that obesity effects on PCa outcomes can be modified by patient age and education and should be studied in the context of these factors. Inconsistent obesity-PCa associations among studies may be related to varying sample population characteristics. Identifying key factors that influence obesity associations will provide critical information about patients whose PCa risks may decrease from targeted interventions. This research may suggest new approaches for prostate cancer intervention via weight management, physical activity, and targeted education, screening and treatment for those patients at highest risk for unfavorable outcomes and related mortality.

Citation Format: Charnita M. Zeigler-Johnson, Knashawn Morales, Jonathan Mitchell, Elaine Spangler, Karen Glanz, Timothy Rebbeck. Modification of obesity effects on prostate cancer outcomes by age and education. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3722. doi:10.1158/1538-7445.AM2015-3722