Obesity and prostate cancer aggressiveness among African and Caucasian Americans in a population-based study

Background: This study evaluated obesity and prostate cancer aggressiveness relationship in a populationbased incident prostate cancer study. Methods: The North Carolina - Louisiana Prostate Cancer Project includes medical records data for classification of prostate cancer aggressiveness at diagnosis by using clinical criteria for 1,049 African American (AA) and 1,083 Caucasian American (CA) participants. An association between prostate cancer aggressiveness and obesity, measured using body mass indices (BMI) and waist-to-hip ratio (WHR), was assessed using ORs and 95% CIs adjusted for confounders. Results:Asignificantly positive association was found between prostate cancer aggressiveness and obesity. The ORs for high aggressive prostate cancer among prediagnosis obese and severely obese were 1.48 (95% CI = 1.02-2.16) and 1.98 (95% CI = 1.31-2.97), respectively, compared with normal weight research subjects. Race-stratified results suggested the association is stronger among CAs. Interaction model showed that normal weight AAs had more aggressive prostate cancer than normal weight CAs (OR = 2.69, 95% CI = 1.36-5.30); severe obesity was associated with aggressive disease in AAs (OR = 3.90, 95% CI = 1.97-7.75). WHR > 0.98 among all research subjects adjusted for race was significantly associated with high aggressive prostate cancer (OR = 1.42, 95% CI = 1.00-2.00) when compared with WHR < 0.90. The stratified result is less clear among AAs. Conclusions: This study shows a positive association between obesity and aggressive prostate cancer. AAs have more aggressive prostate cancer in general than CAs even at normal weight. Therefore, the association between obesity and aggressiveness is not as evident in AAs as in CAs. Impact: This study provides a unique opportunity to examine impact of race on obesity and high aggressive prostate cancer relationship.